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Konveka FH4-H convectors with forced convection (with fans) are the most suitable heating devices for working with condensing boilers. They not only ensure the highest level of thermal comfort indoors, but also the greatest heating economy for the following reasons:

- Maximizes the efficiency of condensing boilers, ensuring a low return water temperature (up to 25°C).

Maximizes use of free heat from human activity and solar energy, using only the amount of thermal energy needed to maintain the set temperature, saving 20 - 30% of heating costs.

Accurately maintains the set room temperature (accuracy 0.5°C), ensuring a high level of comfort.

Develops high power, even when working with very low water temperatures.

Condensing boilers (gas or liquid fuel) reach their maximum efficiency when working with low-temperature water. It should be clarified that here we’re talking about the temperature of the returning water from the heating system. It’s this water that’s used for cooling and condensation of exhaust gases.

 

 

Figure 1:  Schemes of non-condensing and condensing boilers

 

 

Everything happens as follows (see Fig. 1): the temperature of exhaust gases from the boiler with combustion products reaches 140 - 200°C. In a condensing boiler, before entering the chimney, they first pass through the condenser - spec. heat exchanger (marked in red in the picture), where it transfers its heat to the water returning from the heating system. Therefore, preheated water enters the combustion chamber and, in order to raise its temperature to the required level, less fuel is consumed.

 

In addition, if the temperature of the return water entering the condenser doesn’t exceed 54°C, condensation of the water vapor present in the flue gas takes place, during which additional water evaporation energy is obtained and used. In this, so-called "condensing" mode, the boiler works most efficiently - it produces the most heat from the used gas.

 

From the boiler efficiency curve (see Figure 2) it can be seen that as the return water temperature is further reduced, the boiler efficiency continues to increase, so it’s important to keep the return water temperature as low as possible.

 

 

 

Figure 2: Efficiency curve of a condensing boiler

 

The lowest return water temperatures up to 25°C can get in heating systems with underfloor heating or convectors.

 

However, although underfloor heating makes good use of the efficiency of condensing boilers due to its huge inertia, it cannot take advantage of additional free heat emitted by people, household appliances or the sun. As a result, the free heat isn’t used, which can reach up to 15 - 20% of the total heat demand of modern buildings. Therefore, this heating method cannot be considered economical (read more here).

 

Meanwhile, FH4-H convectors have the lowest inertia of all heating devices, so they maximize the use of additional energy. Furthermore, since they’re powerful even when working with low-return water temperatures, FH4-H convectors are best suited for working with condensing boilers.

 

How to select and operate FH4-H convectors with condensing boilers?

 

Above we discussed the importance of the temperature of the water returned from the heating system for the efficiency of condensing boilers. Meanwhile, the temperature of the supplied water doesn’t affect the efficiency. Therefore, in order to make better use of the FH4-H's capabilities, we recommend keeping the supply water temperature higher, e.g., 55°C. In this way, we will have more power and a decent reserve of it (if necessary, the device can also work with 95°C water).

 

Also, the sound level emitted by heating devices is always important, so we recommend selecting and operating FH4-H convectors at a fan rotation speed no higher than:

  1. 40% of the maximum in bedrooms;
  2. 60% of the maximum in rooms of other purpose.

When operated in this way, their work is practically inaudible. In addition, the fans of the FH4-H convectors don’t work all the time: after reaching the set room temperature, they are stopped and restarted only when there is a need for heat. Read more about the sound emitted by convectors here.

 

Table 1 shows the approximate areas of rooms that can be heated with one built-in FH4-H convector of a certain length.

 

Length, cm

Heating power, W

Area of heated room, m²

by energy efficiency class

A++

A+

A

B

C

85

256

10

7

5

4

3

115

443

18

12

9

7

6

165

764

31

20

15

12

10

190

925

37

25

19

15

12

245

1 246

50

33

25

20

17

290

1 570

63

42

32

25

21

 

Table 1: Areas of heated rooms, choosing built-in FH4-H convectors of various lengths.

Data given at supply/return/room temperatures of 55/25/20°C respectively and fan rotation speed - 40% of the maximum

 

Example. According to the data presented in Table 1, we can see that the power of one 190 cm long built-in FH4-H convector is enough for a 19 m² room in an Energy Efficiency Class A building.

 

What to do if the power of the devices is still too low? In buildings with lower energy efficiency, the power of the devices may not be sufficient. In this case, we recommend choosing larger convectors or a larger number of them (several in the room). It’s also possible to increase the temperature of the supply water and reducing the flow so that the temperature of the return water does not increase. If that's not enough, you can increase the speed of the fans up to 80% of the maximum. At this speed, the fans are still rather quiet - their sound pressure is 21 - 25 dB(A) depending on the length.

 

What if the devices don’t have enough power? In lower energy efficiency class buildings, appliances may not have enough power. In this case, we recommend increasing the water temperature by reducing flow so that the return temperature does not rise. If this is not enough, the fan speed can be increased to 60% of the maximum. At this speed, the fans are still quiet enough - they emit a sound pressure of 18 to 21 dB (A) depending on the length.

 

You can find out the power of the device at different temperatures or fan speeds here.

Konveka wall-mounted and in-floor fan coils are designed to work with heat pumps. They not only ensure the highest level of indoor comfort throughout the year, but also maximize the efficiency of heat pumps.

 

In addition, all types of heat pumps work on the same principle as air conditioners, so they can prepare not only warm water for heating, but also cold water for cooling. In this way, using:

             - one energy source - a heat pump;

             - the same system - pipeline, collectors, pumps, etc.;

             - the same heating-cooling devices - fan coils

as a result, this ensures thermal comfort throughout the year. In addition, this makes air conditioning systems with traditional air conditioners unnecessary.

There are two main types of heat pumps for heating-cooling: air-to-water and geothermal. The operating principle of both types is the same, the only difference is that air-water heat pumps use the heat or cold of the ambient air, while geothermal heat pumps use heat from the ground. Since the ground temperature at the depth from which geothermal heat pumps draw energy is constant, the efficiency or COP (coefficient of performance) of this type of device remains constant throughout the year (see Figure 1).

 

Figure 1: Efficiency curves of both types of heat pumps with changes in air temperature

 

 

Air-to-water heat pumps use ambient air at a constantly changing temperature, so their COP is constantly changing.

 

However, there is one parameter that has a very similar influence on the COP of both types of heat pumps – it’s the temperature of the heat carrier being prepared (hereinafter referred to as water) (see Figure 2).

 

Figure 2: Dependence of COP on the temperature of the prepared water at an outdoor temperature of 2°C

 

 

As we can see, the lower the water temperature prepared by the heat pump (in heating mode), the higher its efficiency.

 

In addition, all types of heat pumps work on the same principle as air conditioners, so they can prepare not only warm water for heating, but also cold water for cooling. Therefore, by choosing heating devices with the possibility of cooling, we have thermal comfort throughout the year.

 

It’s  interesting that in individual buildings there are often situations where the heat pump is used only for heating in winter (it’s simply turned off in summer), and air conditioners are additionally installed for cooling, which in principle are heat pumps.

This almost doubles the cost of equipment and its installation, increases the expenses of serviced equipment, and the aesthetics of the building and premises are impaired.

 

Thus, for efficient work with heat pumps, heating devices must:

1. Be able to achieve the required heating power at low water temperatures.

2. Have cooling capabilities.

 

Konveka trench heating-cooling devices FCH (for installation near large windows) and wall-mounted fan coils WMCF (for installation under windowsills) are characterized by these characteristics.

 

 

Konveka FCH trench heater for heating and cooling

Konveka WMCF wall-mounted convector for heating and cooling

 

These devices are designed to work with heat pumps, so by making maximum use of their efficiency, they ensure comfort at home all year round.

 

They develop sufficient heating power at extremely low water temperatures - from 25°C. They can also work with higher temperatures - up to 95°C, so they have a huge reserve of heating power.

 

In cooling mode, they can work both above and below the dew point (they have drain pans), i.e. with temperatures from 7°C.

 

The mentioned models are extremely fast (they reach the required power or turn off completely in a few seconds), so they quickly and accurately adjust to the settings of the room thermostat. This allows that the premises never overheat, using every watt of energy from human activity or solar energy (read more here).

 

All Konveka convectors are equipped with the most efficient EC type fans, the sound pressure of which is at the limit of human hearing - about 20dB(A) (Lithuanian hygiene standard HN 33:2011 states that the permissible sound pressure in residential premises at night is 35dB(A)). In addition, they are acoustically isolated and controlled by a unique algorithm that ensures a minimum level of emitted sound. In many countries around the world, there are thousands of satisfied customers who use Konveka convectors with fans in their bedrooms. Read more about the sound emitted by Konveka convectors here).

 

Table 1 shows the areas of rooms that can be heated with one built-in FCH2 convector of a certain length.

 

 

Length,

cm

 

Heating power, W

Areas of heated premises, m²

by energy efficiency class

A++

A+

A

B

C

120

471

16

12

9

8

7

170

847

28

21

17

14

12

200

941

31

24

19

16

13

250

1 318

44

33

26

22

19

300

1 695

56

42

34

28

24

 

Table 1: Areas of heated rooms, choosing built-in FCH2 convectors of various lengths.

Data is given at supply water/return water/room temperatures

respectively 35/30/20°C and fan rotation speed - 40% of the maximum

 

Example: According to the data presented in Table 1, we can see that the power of one 200 cm long built-in FCH2 convector is enough for a 19 m² room in an Energy Efficiency Class A building.

 

You can find out the heating and cooling power of each mentioned device at different temperatures or fan speeds here ("output" section).

Free thermal energy is the energy that is released indoors by human activity (household appliances and people themselves) and the sun. It can provide up to 15-20% of the total heat demand in modern buildings. This means that by using free thermal energy, costs for building heating are reduced by 15 - 20%.

 

How to take advantage of it? Thermal energy released by human activity and the sun enters the premises very dynamically: 2000W can be released at one time, and only 200W after 30 minutes. Therefore, in order to use it, you need to have a heating system that quickly adapts to the changing heat demand. This is implemented by:

 

1. Installing room thermostats in each room.

2. Using as little inert heating devices as possible, quickly and accurately executing "commands" of thermostats.

 

Convectors and fan coils are heating devices with the lowest thermal inertia. Controlled by room thermostats, they use every watt of human activity and solar energy. Conversely, when using inert heating devices, e.g., underfloor heating, this energy is lost.

As the energy efficiency of buildings increases rapidly, less and less energy is used for their heating systems. Unrenovated buildings constructed 30 years ago require 3-5 times more energy for heating than modern buildings.

 

 Meanwhile, the amount of free energy released by human activity and the sun remains the same:

- although the efficiency of some household appliances has increased, their quantity has also increased. 30 years ago, not every house had a dishwasher, dryer, microwave, or computer;

- although the quality of the windows has improved, their size has also increased;

- the amount of heat released by a person hasn’t change.

 

Due to these reasons, the share of free energy in the heat demand of modern buildings has increased significantly - now it can reach 15-20%.

 

The amount of free energy released by human activity and the sun depends on:

 

1. Type, quantity, and duration of use of household appliances (see Table 1).

 

Household Appliance

Approx amount of heat

Oven

3 000 W

Stove

2 000 W

Kettle

2 000 W

Coffee machine

1 500 W

Iron

1 500 W

Vacuum cleaner

300 W

Washing machine

300 W

Dryer

300 W

Dishwasher

300 W

Lightning

100 W

TV

80 W

Computer

50 W

Internet router

20 W

 

Table 1: Approximate amount of heat emitted by household appliances

 

2. Intensity and duration of direct sunlight through the windows. 1 m² of sunlit area emits about 1000 W of heat.

 

3. The amount of people and the duration of their stay in the premises. It's estimated that a person indoors emits about 100 - 150W of heat into the environment.

 

 

In order to "catch" all this energy, you need to have a heating system that quickly adapts to the changing heat demand. In practice, this is implemented very simply. All you need is to:

 

1. Install room thermostats in each room.

Room thermostats constantly measure the temperature of the room and, in order to keep it equal to the task, send commands to the heating device to increase or decrease the heating intensity. They are the "head" of one or a group of heating devices in the room.

 

2. Use heating devices that quickly and accurately execute thermostat "commands".

The heating demand in each room changes significantly throughout the day, therefore, in order to maintain the desired temperature, it’s necessary to constantly change the work intensity of the heating devices. The lower their inertia, the faster and more accurately they can change the heating intensity according to the signals received from the thermostat. Therefore, it’s important to choose heating devices that are as quickly-to-respond as possible. The least inert heating devices are convectors and fan coils.

 

Does heat demand really change so significantly?

It changes unpredictably fast and unpredictably often, with a wide range of temperatures. Perhaps the most accurate description would be to call the change in heat demand chaotic.

To illustrate, let's take an individual house with an area of 100 m². Let's say that at a certain time, 2700W of thermal power is needed for its heating. When a family of four comes home in the evening, the lights, at least 2 computers, a stove and a TV are turned on. This human activity emits a total of about 2680W of heat into the premises. All this happens within 10-15 minutes. The building's heat demand during this time period drops from 2700W to 20W (see Fig 1).

 

Figure 1:  Exemplary variation of heat demand during human activities in the household

 

Later, at some point, the stove will be turned off, the dishwasher will be turned on, someone will go out to walk the dog, or turn on the kettle, someone will leave the door to a cooler bedroom opened, guests will arrive, etc. i.e. All the mentioned events, as we can see, change the demand for heat very dynamically and are almost unpredictable.

 

How will high-speed heating devices work in such a house, e.g. fan coils or convectors controlled by room thermostats?

 

The room thermostat will detect that when the family returns home, the temperature has increased by 0.5°C due to their activities. It will instantly signal the devices to stop heating, which will stop heating within seconds. From this moment on, the building will be heated by the free heat emitted by household appliances and people. The thermostat will wait until the temperature drops by 0.5°C below the set point, then start the devices at the lowest power (20% of the maximum) and control whether it is enough to reach the set temperature. Once the temperature is reached, it will turn off the heating again. So heating with convectors or fan coils will use up every watt of human activity and solar energy.

Such a system will also perfectly perform the task of lowering the temperature of rooms when they’re not in use. The system will shut down and wait for the temperature to naturally drop to a programmed lower level, e.g. from 22°C to 18°C and will keep it at this level. When it’s time to return the temperature to a higher level, it will turn on again and reach 22°C in 15 - 20 minutes.

If something suddenly changes, e.g. someone comes home early from school, just increase the temperature on the room thermostat and it will warm up in 15-20 minutes.

 

For comparison: how will inert heating devices, e.g., floor heating, work in such a house?

 

In this case, everything will start in a similar way: the room thermostat will determine that when the family returns home, the temperature has increased by 0.5°C due to their activities. It will instantly send a signal to the underfloor heating collector to stop heating, where in about 1 min. water circulation in the underfloor heating circuits will be stopped.

However, the rooms will continue to heat up because underfloor heating is a very inert heating device. It will take 2-4 hours for the floor to cool down (depending on the thickness of the concrete layer) and during this time the accumulated heat will spread into the room. Let's add the heat released by human activity during this period and we will have up to 2°C higher than the set room temperature. This is unnecessary or excess space heating, for which the family will have to pay the price.

If the family gets too hot inside and opens the window, energy will be released outside. If they wouldn’t dare to do this, they’ll gradually get used to living at a higher temperature and this will be their new, more expensive, norm.

Due to the inertia of underfloor heating, it isn’t efficient to save energy by reducing the temperature of rooms when they are not in use. In order to lower the room temperature, the underfloor heating will need to be turned off a few hours before, because the heated floor surface will cool down the rooms very slowly. After the rooms have cooled down to the desired level, e.g., 18°C, the heating will come back on, but the floor is now cold and will take several hours to warm up. During this time, the room temperature will drop even lower, e.g., up to 16-17°C, so to raise it, the floor will have to be heated longer. When 18°C is reached again, it will be switched off, but the room temperature will continue to rise to 19-20°C as the floor is well warmed up.

If something suddenly changes, e.g., someone who comes home from school early, they will have to endure the cold because increasing the temperature on the room thermostat will only increase it in a few hours.

 

Conclusion

Non-inert heating devices, such as Konveka convectors and fan coils, make the most of dynamically changing human activity and free energy released by the sun, saving up to 20% of the building's thermal energy. Meanwhile, this energy is lost when using inert heating devices.

 

When When choosing heating-cooling devices with fans, customers sometimes express concern that they can make too much noise.

 

Konveka convectors are known as one of the quietest heating devices because:

        - they are equipped with exceptionally quiet EC type fans

        - all fans are mounted on noise and vibration insulating elements

        - the convector casings are acoustically isolated from the building structures

        - Konveka room thermostats work according to a unique algorithm that ensures the lowest fan rotation speed and the least amount of noise generated

        - the fans of Konveka convectors and fan coils, controlled by room thermostats, rotate only as needed, i.e. about 30% of the total time.

 

The sound level emitted by convectors is also highly dependent on their appropriate selection and operation, so in this article we will explain how to select and operate Konveka convectors so that the sound they emit indoors is practically imperceptible. There are thousands of satisfied customers heating their bedrooms with Konveka convectors with fans.

Acceptable sound levels

 

The sound levels emitted by all household and heating-cooling devices are usually presented in the technical data in units of sound pressure - decibels, dBA.

In order to define what sound corresponds to a given dBA value, we provide sound pressures for typical activities and environments.

 

60

Normal conversations at a distance of 1 m

55

Big office

50

Dishwasher in the next room 

45

Moderate rain

40

Library 

35

Quiet suburbs at night

30

Whisper nearby

25

Whisper at a distance of 1 m

15

Record studio

10

Breathing

Table 1: Typical emitted sound pressures, dBA

 

 

The requirements for the sound pressure for rooms of a certain purpose are specified in table 2.

 

Room

Requirements

in hygiene standards, dBA

The highest comfort level requirements, dBA

Bedroom at night

35

25

Living room during the day

40 - 45

35

Office during the day

45

40

Table 2: Sound pressure requirements for rooms of a certain purpose

 

 

Origin of sound

The only sound-emitting elements inside convectors and fan coils are their fans, therefore, the quality of fans is critical. In Konveka heating-cooling devices, fans are installed only with EC type motors (see photo on the right). Such fans are not only 7 times more economical than the usual AC type, but also work exceptionally quietly.

 

In addition, all fans in the Konveka convector casings are fixed through specially made rubber and plastic insulators. They isolate the casings from the vibrations and noise emitted by the fans, further reducing the overall sound emitted by the devices.

 

The right choice

Sometimes the devices "make noise" when the power selected is too low, so they are forced to work at maximum fan speed. In fact, they must be selected in such a way that they achieve the required power at an acceptable sound pressure level (see Table 3). Convector results will be:

- never "make noise" more than specified in table 3

such an (acceptable) sound pressure will be emitted only during extreme cold

 

Table 3: Sample technical data of convectors

 

Example. We are choosing the FH4-H convector for the bedroom. In order to ensure the maximum level of comfort, based on table 2, we determine the maximum sound pressure acceptable to us, e.g., 25 dBA. In Table 3 we see that the closest sound pressure (24 dBA) is achieved at 80% fan speed. When the water temperature is 75/65/20°C, the maximum power of the convector is 957W. If this is enough, we choose this model, if not, we look for a more powerful one

It should be added that this model will emit a sound of 24 dBA only at the lowest outdoor temperatures, when its full power is needed (up to 10 days a year), at all other times it will emit 0 - 19 dBA.

 

Operation

The most common error in the operation of convectors with fans and fan coils is insufficient temperature of the energy carrier (hereinafter referred to as water). This happens when the temperature of the boiler water supplied from the building is reduced automatically as the outside temperature increases ("operation according to the outside temperature").

 

When the outside temperature rises, lower temperature water is supplied to the heating devices, and at the same time less energy is supplied, so they emit less heat. The fans are then forced to spin at higher speeds to maintain the required power and make more noise. A situation arises when the power of the devices is regulated not by room thermostats (as it should be), but by the temperature of the supplied water, so the fans rotate longer and their rotation speed does not decrease.

 

Heating-cooling devices work correctly when they are supplied with water at a constant temperature (prescribed in the heating project) throughout the heating season. Then they are controlled only by room thermostats, which regulate the power of the devices by changing the speed of the fans or turning them off altogether. In this way, the fans are turned on only when needed and only at the right speed, ensuring the lowest level of emitted sound.

 

 

Management

In order to minimize the level of sound emitted by heating and cooling, the choice of room thermostats for their management is very importantThere are many thermostats on the market that regulate the power of the devices, maintaining the set temperature in the rooms with sufficient accuracy, but many of them do this without taking into account the noise they make.

 

Room thermostats Konveka RTB24 (see the photo on the right) work according to a unique algorithm that maintains the set temperature in the room, ensuring the minimum speed of rotation of the fans, and at the same time the lowest level of emitted sound

 

They also ensure that the fans work only about 30% of the total operating time. This way, 70% of the time the fans are not running, so the devices don't make any noise at all.

 

Placement

The audible noise emitted by heating and cooling devices also depends on their position in the room. Sound waves travel in straight lines and get weaker the more obstacles they encounter in their path. Therefore, the higher the sound source is, the easier it is for the sound to reach our ears without obstacles. To give an example, church bells are always installed in their highest towers so that as many people as possible can hear the call to worship.

 

Air conditioners are always installed in the upper part of the room: on the ceiling or close to it. All the noise they emit goes directly to our ears, so we hear higher levels of noise.

 

The situation is different with convectors - they are always installed under windows, on the floor, or on the wall, i.e., in the lower part of the room. The sound they emanate almost always meets obstacles (curtains, furniture, etc.), so the audible level is lower than the standard air conditioners.

 

Conclusion

With the correct selection, operation and management of Konveka convectors, the sound they emit in the room may not reach 20 dBA, i.e,. be almost inaudible. In addition, the fans work only for about 30% of the total operating time, the rest of the time they are turned off. Therefore, convectors and fan coils can be used without hesitation even in bedrooms.

 

Heating rooms only as much as needed and only when needed, precisely maintaining the set temperature (without overheating), allows you to save about 20 - 30% of heating costs. This can only be achieved using fast-responding heating devices such as convectors.

 

The convector heating system controlled by room thermostats meets the requirements for economical heating devices by:

 

- accurately maintaining the set temperature of the rooms, without overheating them;

maximizing the use of free energy from human activity and the sun;

- strictly adhering to the set heating schedule, reducing the temperature of the rooms when they are not in use.

 

Underfloor heating, being extremely inert, does not meet the requirements for economical heating devices because:

it’s unable to cool down quickly, it constantly overheats the premises by several degrees, unnecessarily wasting thermal energy. It is known that if the room is overheated by only 1°C, heat consumption increases by 6%;

- it cannot use additional heat energy from human activity or the sun, the amount of which can reach up to 15-20% of the total energy demand of the building;

it’s unable to maintain the set heating schedule - another 10% of thermal energy is lost.

Specialists say that rational heating of a premise can save up to 20-30% of its costs. In order to heat rationally, rooms should be heated only as much as needed and only when needed. This can be achieved by:

 

1. Accurately maintaining the set temperature (without overheating the premises in any way).

2. Using free energy from human activity and the sun.

3. By setting a heating schedule that lowers the temperature of the rooms when they are not in use, i.e. when family members are at work, school, etc.

 

 

Here's how to do it:

 

   1. Room thermostats with daily and weekly programming are installed in each room.

Room thermostats constantly measure the temperature of the room and, in order to keep it equal to the task, send commands to the heating device to increase or decrease the heating intensity. They are the "head" of one or a group of heating devices in the room.

 

   2. High-speed heating devices are used, which quickly and accurately execute the "commands" of the thermostats.

The heat demand in each room changes dynamically during the day and week, therefore, in order to maintain the desired temperature, it’s necessary to constantly change the work intensity of the heating devices, adjusting it to the heat demand at a certain time. The lower their inertia, the faster and more accurately they can change the heating intensity according to the signals received from the thermostat. Therefore, it’s important to choose heating devices that are as inert as possible.

 

 

How dynamic are the changes of heat demand?

Erratic in every way, it changes fast, significantly, and often. Perhaps the most accurate description would be to call the change in heat demand chaotic. It depends on unpredictable human activity and natural factors:

 

1. Outdoor temperature. During the day, the outdoor temperature changes significantly, so the heat demand also changes.

2. The amount of people and the duration of their stay on the premises. It’s estimated that a person, being indoors, emits about 100W of thermal power into the environment.

3. Intensity and duration of direct sunlight through the windows. 1 m² of sunlit area emits about 1000 W of heat.

4. Type, quantity and duration of household appliances used (see table 1).

 

Household appliance

Approximate amount of heat

Oven

3 000 W

Stove

2 000 W

Kettle

2 000 W

Coffee Machine

1 500 W

Iron

1 500 W

Vacuum Cleaner

300 W

Washing Machine

300 W

Dryer

300 W

Dishwasher

300 W

Lighting

200 W

TV

80 W

Computer

50 W

TV Set

20 W

Internet router

20 W

 

Table 1. Approximate amount of heat emitted by household appliances

 

Points 2 - 4 list the sources of free thermal energy, which, as the energy efficiency of buildings increases, can reach 15 - 20% of the total heat demand of the building.

 

For illustration, let's take an individual house with an area of 100 m², it needs 2700W thermal power for heating. When a family of four comes home in the evening, the lights, at least 2 computers, a stove and a TV are turned on. This human activity emits about 2680W of heat into the premises. All this happens within 10-15 minutes. The building's heat demand during this time period drops from 2700W to 20W (see Figure 1).

 

Figure 1: Exemplary change in heat demand during human activities in the household

 

Later, at some point, the stove will be turned off, the dishwasher will be on, someone will go out to walk the dog, or turn on the kettle, someone will leave the door to a cooler bedroom open, guests will arrive, etc. All the mentioned events, as we can see, change the demand for heat quite dynamically (quickly and significantly) and are almost unpredictable.

 

 

How will both compared systems behave in such a house?

 

1. Convector heating system controlled by room thermostats

The room thermostat will detect that when the family returns home, the temperature has increased by 0.5°C due to their activities. It will instantly send a signal to the convectors to stop heating, which will be executed in a few seconds. From this moment on, the building will be heated by the free heat emitted by household appliances and people. The thermostat will follow until the temperature drops to 0.5°C below the set point, then start the convectors at the lowest power (20% of the maximum) and check if it’s enough to reach the set temperature. Once the temperature is reached, it will turn off the heating again. Convection heating will therefore use every watt of human activity and solar energy.

 

2. Underfloor heating controlled by room thermostats

In this case, everything will start in a similar way: the room thermostat will determine that when the family returns home, the temperature has increased by 0.5°C due to their activities. It will instantly send a signal to the underfloor heating collector to stop heating, where in about 1 min. water circulation in the underfloor heating circuits will be stopped.

However, the rooms will continue to heat up, because underfloor heating is a very inert heating device. It will take 2-3 hours for the floor to cool down, and during that time the accumulated heat will spread into the room. Let's add the heat released by human activity during this period and we will have up to 2°C higher than the set room temperature. This is unnecessary or excess space heating for which the family will have to pay.

 

If the family doesn’t tolerate the increased temperature and opens the window, energy will be released outside. If they don’t dare to do this, they will gradually get used to living at a higher temperature and this will be their new, more expensive, norm.

 

It should be added that more than 50% of operating underfloor heating systems are not controlled by room thermostats at all (especially in multi-apartment residential buildings), so they overheat even more.

 

 

 

Why is underfloor heating so inert?

 

The greater the weight of the heating device, the more mass of material needs to be heated or cooled, the longer it takes and the greater the thermal inertia. The weight of underfloor heating as a heating device is huge - a 1kW device weighs about 2400 kg (adding up the weight of water, pipes, concrete and floor covering). Meanwhile, a 1kW convector weighs an average of 4.8 kg, depending on the model, i.e. about 500 times less.

Figure1: Weights of various heating devices. Comparison with vehicle weights

Underfloor heating transfers heat to the room through the surface of the floor covering, so in order to decrease or increase the temperature of the room, we must first change the temperature of the floor surface. Here’s what happens:

 

1) the water temperature in the underfloor heating system changes first;

2) after that, the temperature of the outer surface of the plastic tubes through which the water circulates changes;

3) later the temperature of the entire concrete layer changes;

4) and eventually the temperature of the floor covering changes.

 

Only then does the underfloor heating power change and the room temperature starts to change.

 

 

 

 

How effectively do the two compared systems maintain the set temperature schedule?

 

 

Nowadays, bedrooms and living rooms are operated only for 8 hours, children's rooms - 16 hours a day, so it’s not worth heating them non-stop. Very often, the temperature of such rooms, when they are not in use, is lowered by 4 - 6°C, in other words, their thermal regime is determined. This allows you to save about 10% of thermal energy and is easier on the heating system. We will examine how both systems will be able to maintain the set thermal regime when the operating temperature is set at 22°C and lowered by 18°C.

 

1. Convector heating system controlled by room thermostats

When it's time to lower the temperature, the system turns off the convectors and waits for the temperature to naturally drop to the programmed lower level - up to 18°C. When the temperature drops, the convectors are periodically switched on and off, precisely maintaining a lower temperature. When it’s time to return the temperature to the operational level, i.e. 22°C, the system turns on the convector at maximum power and within 15 - 20 min. prepares the premise for operation.

If something suddenly changes, e.g. someone comes home early from work or school while the temperature is still 18°C, just increase the temperature on the thermostat of the required room and it warms up in 15-20 minutes.

 

2. Underfloor heating controlled by room thermostats

When it's time to lower the temperature, the system turns off the floor heating, but the heated floor will heat the rooms for another 1-2 hours. When they eventually cool down to the desired 18°C, the heating will come back on, but the floor is now cold and will take several hours to warm up. During this time, the room temperature will drop even lower, e.g. up to 16-17°C, so to raise it, the floor will have to be heated longer. When 18°C is reached again, they will be switched off, but will continue to raise the room temperature to 19-20°C as they are well warmed up, etc. In this way, the temperature will fluctuate until it is time to raise it to 22°C. If at that time the room temperature will be 16°C, it may take 3-4 hours, if 20° - about 1-2 hours, so it’s not clear how long before it should be turned on.

If something suddenly changes, e.g. if someone comes home early from work or school, they will have to endure the cold, because if you increase the temperature on the room thermostat, it will need a few hours to warm up.

 

 

Conclusions

 

The convector heating system controlled by room thermostats meets all the requirements for economical heating devices:

- accurately maintains the set temperature of the rooms without overheating them;

- makes maximum use of free energy from human activity and the sun;

- perfectly supports the set heating schedule, reducing the temperature of the rooms when they are not in use.

 

Underfloor heating controlled by room thermostats does not meet any of the requirements for economical heating devices:

- not being able to cool down quickly, it constantly overheats the premises by several degrees, unnecessarily wasting thermal energy. It’s known that if the room is overheated by only 1°C, heat consumption increases by 6%;

- cannot use additional thermal energy from human activity or the sun, the amount of which can reach 15-20% of the building's total energy demand;

- fails to maintain the set heating schedule, which results in another 10% loss of thermal energy.

 

The demand for heat on the premises changes much more dynamically than the underfloor heating system is able to adapt to it, so it cannot be economical in principle. Like convectors, it can work with low water temperatures, making good use of the efficiency of condensing boilers or heat pumps. However, its use of the resulting heat is extremely uneconomical.

The coldest areas of each room are where it borders the outside - these are windows, external doors, and walls. All of the heat loss of the room is concentrated in these places, therefore, in order to have an even temperature throughout the entire area of the room, we must place the heating devices in these places. It’s irrational to heat at the internal parts of the room because there is no heat loss there. Convectors are always installed under the windows - in the coldest parts of the room, ensuring the most even temperature.

 

Heated floors heat up every square meter of the room with the same power, so it is impossible to avoid temperature zoning: the temperature will always be lower near the windows and external walls, because there is not enough power to cover the heat loss, and higher at the internal parts of the room because it’s heated where isn’t needed.

In most publications, the advantage of underfloor heating is stated as an even distribution of heat in the room.

 

It would be possible to fully agree with such an assumption if we had a well-insulated room without windows, exterior doors and if all its walls had the same heat loss. Underfloor heating heats the entire area of the room equally, so it would be the best heating method for such a room.

 

In reality, each room is different: it has zones with sufficiently large heat losses near windows, front doors or external walls, and zones where they are completely absent - near internal partitions with rooms of a similar temperature.

 

As an example, let's take a 30 m² room with a heat loss of 1200 W. Most of it is concentrated around windows and external walls (see Figure 1). After placing the convectors in those places, we will have the most even distribution of heat in the room. Their power will be sufficient to cover the heat loss of the entire room and will be concentrated where they are and where heating is needed. The rest of the room does not require heating - there is no heat loss there.

Figure 1: Distribution of heat loss (marked in blue) in the room

 

Let's install a heated floor in such a room. Their power is on average 50 - 60 W/m², so if they are installed only near windows and external walls, there won’t be sufficient power. To increase the power, we can increase the floor temperature or area. Since we cannot increase the temperature of the floor above 30°C, we increase the area by making heated floors throughout the room.

 

In this way, every square meter of the room is heated with the same power, even though the heat losses aren’t the same. Therefore, we do not avoid temperature zoning:

 

the temperature at the windows and external walls will always be lower, because there will not be enough power to cover the heat loss;

- closer to internal partitions the temperatures will be higher, because it will be heated where there are no losses.

 

This wouldn’t be a problem if the air in the room was intensively mixed, equalizing the temperature. However, underfloor heating is mostly radiant heating (infrared heating), so it hardly causes air movement. Mechanical ventilation of rooms doesn’t perform this task either, because:

 

a)   it is not intended to mix air, but to replace old air in the room with fresh air;

b)   for sufficient air mixing in the room, the intensity of ventilation is not enough even after it’s installed according to STR requirements. For example A 20 m² (5.0 x 4.0 x 2.8 m) bedroom for 2 people requires a fresh air volume of 28.8 m³/h. The average speed of air movement in such a bedroom is only 2.6 m/h.

 

When installing underfloor heating, an attempt is made to alleviate temperature zoning in every possible way by increasing the temperature of the floor near the windows and outside walls:

 

1. Underfloor heating pipes are compacted, i.e., the distance between them is reduced to 5-10 cm, when in the rest of the room it is standardly 20 cm (see Figure 2).

In this way, the uniformity of the floor temperature at the windows is increased, increasing the floor temperature between the tubes by several degrees. However, at a fixed water temperature (the floor is usually supplied with water at a temperature of less than 30°C),the effect will be small - certainly not enough to cover the heat losses near the windows.

 

Figure 2: The method of installation of heated floors to increase the power at the windows

 

2. Pipes from the collector are first laid near the windows and outside walls.

We can't expect much from this measure either, because underfloor heating pipes are usually laid in a spiral, with the coldest pipe next to the hottest (see Figure 2), so the average floor temperature at the windows doesn't change much.

 

Thus, the statement that underfloor heating ensures uniform temperature distribution in rooms is false, and temperature zoning is inevitable in this case. The most even temperature distribution in the rooms can only be ensured by heating devices of sufficient power placed near the windows.

Using the underfloor heating system for cooling (when the heat source is a heat pump) is attractive at first glance: we can "kill two birds with one stone" using the same system. However, there are a number of points that should be considered before taking this step:

1. Due to power limitations, floor cooling capacity provides, at best, 25% of room cooling demand.

2. High probability of condensation on the cooled floor. There's a risk of mold, slipping, and damage to floor coverings, furniture, or carpets.

3. Extremely uncomfortable: in summer, we want to feel the pleasant coolness of the air in the room, not cold feet - after all, cold air is heavier and stays near the floor.

4. Due to huge inertia, we'll never have a constant temperature indoors.

5. Due to inertia and underpowering the system won't turn on and off as needed, but will operate throughout the cooling season, using energy inefficiently.

The heating/cooling system with Konveka fan coils doesn't have the above-mentioned disadvantages. They are designed to work with heat pumps, so they ensure comfort all year round.

The operating principle of underfloor cooling is based on heat absorption. This means that the floor absorbs part of the heat (infrared rays) radiated from heated surfaces in the room: walls, ceilings, furniture, people, etc.  Simply put, it works in reverse to underfloor heating: in the case of underfloor heating, the heated floor heats the cooler surfaces in the room, and in the case of underfloor cooling, the heated surfaces heat the floor, giving it their own heat.

We will discuss the main aspects of using an underfloor heating system for cooling. 

 

Power

The floor cooling capacity directly depends on two parameters:

1. floor surface temperatures: the lower the temperature, the greater the cooling power;

2. floor surface area: the larger the cooling area, the greater the power.

 

Due to the following parameters, the power of such cooling is limited:

1. the temperature of the floor cannot be greatly reduced because condensation will appear on it, and the "safe" temperature is not enough to achieve the required power;

2. the floor area cannot be increased - it cannot be larger than the area of ​​the room.

Due to these power limitations, floor cooling capacity is calculated to provide, at best, 25% of the room cooling demand. It's like having a car that only brakes on one wheel instead of all four. This means that indoor temperatures can be 1-2°C cooler, but this isn’t enough to ensure temperature comfort throughout the warm season. When we’re not be able to sleep during the heat, we will inevitably start to consider the purchase of more powerful cooling devices.

 

Having chosen floor cooling, we have to limit ourselves to the choice of floor covering and interior elements. Not all floor coverings transmit cold well, and furniture, carpets or other items that usually cover 20-70% of the floor greatly reduce the already insufficient cooling power.

 

The same heat pumps that prepare cold water for the floor cooling system also prepare hot water for the building's plumbing system. They cannot perform both tasks at the same time, therefore, while hot water is being prepared, the cooling of the floor is stopped, so its power decreases even more.

 

 

Chance of condensation

 

One of the biggest problems with floor cooling is that when adverse conditions occur, condensation can form on the surface of the floor. All it takes is a certain air temperature/humidity ratio at a fixed floor temperature, and condensation forms.

Figure 1 shows the conditions for dew point formation.

 

Figure 1: Dew point formation curves

 

Example. Suppose we have the following conditions:

the temperature of the cooled floor is 19°C. This is considered a safe temperature for condensation (some sources recommend keeping it at 18°C);

the air temperature in the room is 25°C. For most people, this is a comfortable room temperature during the summer.

From the graph it can be seen that under these conditions, 70% of air humidity is sufficient for condensation to form on the floor surface. At a floor temperature of 18°C, 65% air humidity is sufficient, which is considered normal humidity in the warm period of the year.

Air humidity outside during rain or after the sun shines reaches 90-99%, because intensive evaporation of water takes place. If at that time the ventilation system is turned on, or air from the outside enters through an open vent, window or door - we have a wet floor. If we turn off the ventilation system and seal everything tightly, the humidity in the air will still come from human activities (cooking, people breathing, sweating, plants, housework, etc.). To make matters worse, the underfloor cooling system doesn’t dehumidify the indoor air in the summer like other cooling devices.

Thus, we can conclude that the probability of condensation formation on the cooled floor is high. And what are the consequences? Here are the main ones:

1. The possibility of slipping. It is impossible to predict when condensation will appear on the floor, so it is possible to slip without noticing it. The highest risk group is the elderly.

2. Damaged floor covering and furniture. Many residential floor coverings are not water-resistant, so condensation can permanently damage them.

3. Probability of mold growth. Condensation is released over the entire floor surface, even in hard-to-reach places: behind baseboards, under carpets, furniture, etc. If the situation repeats itself and the moisture doesn’t dry properly, the chances of mold growth increases.

As measures to prevent condensation, the following are generally suggested:

1. Use condensate sensors. However:

        a) such sensors are triggered only when the dew has already separated, so the floor will still be somewhat dewy, maybe not wet

        b) upon sensing condensation, the sensors signal the cooling system to stop the supply of chilled water to the floor, but the floor is very inert and will actually rise to a safe temperature only after 1-2 hours. The floor will be wet all the time.

2. Increase the temperature of the floor. This reduces the chance of condensation, but does not eliminate it. In addition, the already-insufficient cooling power decreases even more.

 

Comfort

 

Let's imagine: on a beautiful summer day, we are in a living room with an air temperature of 25°C and a floor temperature of 19°C. We sit on the couch and watch a movie. Where are our feet? That's right, on the couch. Even in summer, no one wants to keep their feet on a cold floor. We want to feel the pleasant coolness of the air in the room, not cold feet.

 

Our limbs are the coolest parts of the body, so a cold floor is the last thing we want in a cozy home. Many people even leave the underfloor heating on in their bathrooms during the summer because they don't want to stand barefoot on cold tiles.

 

Proponents of heated-cooled floors write that floor heating is very comfortable because our feet are in a warmer area and our head is in a cooler area. They consider underfloor cooling to be just as comfortable, even though underfloor cooling creates the exact opposite environment. How should this be understood? Is our sense of comfort turned upside down in the summer?

 

On the other hand, with floor cooling, due to low power and huge inertia, we will never have a constant temperature in the rooms. Let's say you managed to reach a temperature of 25°C at home. Then the sun peeked through the window, someone started cooking, someone turned on the TV, more people gathered and the temperature rose to 27-28°C. Underfloor cooling cannot handle this amount of heat.

 

 

Cost-Effectiveness

 

There is no point in comparing the cost-effectiveness of underfloor cooling with other cooling devices, because underfloor cooling simply does not produce enough power. However, there are a few points to note:

 

1. The floor cooling system (due to high inertia and too little power) does not turn on and off as needed, but operates throughout the cooling season. It will not be turned off even when you leave for the weekend - after all, it will need half a day to reach the nominal power and cool the premises.

2. The floor cooling system has 5 times higher pressure losses than, for example, a convector system, so the electricity consumption of circulation pumps is 5 times higher.

 

 

Alternative

 

A good alternative to floor cooling is cooling with floor or wall fan coils. They are designed not only for cooling in summer, but also for heating in winter, and they don’t have any of the above disadvantages:

 

1. Their power is sufficient for cooling rooms of any size.

2. Their power is not limited by the amount of furniture or carpets in the room.

3. With sufficient power, they can be idle while the heat pump prepares hot water, then quickly compensate for the lack of cold.

4. Condensate released on their heat exchangers is collected in condensate baths and led to the sewage system. No condensation on the floor! At the same time, excess air humidity is collected during the warm period of the year.

5. They don't cool the floor, so it's nice to stand on them.

6. They distribute cool air well indoors, so when you’re inside, you feel a pleasant coolness throughout your body.

7. They ensure a constant indoor temperature, even with a dynamically changing cooling demand.

8. Saving energy, works as needed, i.e., only when needed and as much as needed. This perfectly maintains the set temperature regime.

 

We suggest you consider using Konveka recessed and suspended convectors for heating and cooling in your building.

 

 

 

Konveka FCH is recessed into the floor fan coil

Konveka WMCF is suspended fan coil

 

Contact us, and we’ll explain the principles of fan coil operation, and advise how to best use their advantages. We have no doubt that you’ll be satisfied.

The higher the pressure losses of the heating system, the higher the electricity consumption for its operation.

 

Underfloor heating systems have the highest pressure losses, because the water in the system flows through very long circuits of small-diameter pipes.

 

The pressure losses of convectors are, on average, 5 times lower. This means that the energy consumption of circulation pumps in convector heating systems is, on average, 5 times lower.

Pressure loss in the heating system is an undesirable, but inevitable phenomenon. The dynamic pressure of the heat carrier (hereinafter, referred to as water) is created by the pumps installed in the system, so the pressure loss directly affects the energy consumption of the pumps. In other words, the higher the pressure losses of the heating system, the higher the electricity consumption for its operation.

 

The pressure loss of the heating system depends on:

   1. Cross-sectional area of heating system elements (usually pipes). The smaller their cross-sectional area, the greater the pressure loss.

   2. The length of the elements of the heating system. The greater their length, the greater the loss.

   3. Water flow. The higher the water flow in the system, the higher the pressure loss.

   4. The roughness of the inner surface of heating system elements. The greater the roughness of the surfaces, the greater the losses.

 

Underfloor heating systems have the highest pressure losses compared to all other systems, because:

   1. Water in the system flows through very long, up to 80-130 m, pipe contours.

   2. Small inner diameter of pipes. For example, one of the most popular pipe sizes used for underfloor heating, 17 x 2.0 mm, has an inner diameter of only 13 mm.

 

Example

Let's calculate the pressure loss of the most popular pipes used for underfloor heating. Let's assume that the average distance between the tubes is 18 cm (10 cm near the windows and 20 cm in the rest of the room).

 

Pipe outer diameter and wall thickness, mm

17 x 2,0

18 x 2,0

20 x 2,0

Maximum length of 1 circuit pipe, m

85

104

127

Average distances between tubes, m

0,18

0,18

0,18

Heated area, m²

15,3

18,7

22,9

Heating power, W (taking 60 W/m²)

918

1 123

1 372

Water flow, l/h, when dT = 5°C (29/24°C)

113

138

168

1 m pipe pressure loss, kPa (when average water t = 26,5°C)

0,082

0,067

0,055

Pressure losses of the entire circuit, kP

6,9

7,0

7,0

Calculated pressure loss, Pa/W

7,5

6,2

5,1

 

We can see that the average pressure loss in the largest underfloor heating circuit is 6.3 Pa/W, while the pressure loss of the convectors, even at low water temperatures (35/30°C), is on average 1.2 Pa/W, i.e., 5.2 times smaller. This means that the energy consumption of circulation pumps in the case of underfloor heating is on average 5.2 times higher.

"Low allergic effect" is often mentioned among the advantages of underfloor heating - less dust is transferred by convective air flows, and underfloor heating prevents the accumulation of dust in the floor covering.

If underfloor heating prevents the accumulation of dust in the floor covering, then where does it disappear? Although underfloor heating is largely radiative, it definitely has a convective component: the air near the floor warms up, and since it’s lighter, it rises, bringing dust with it. This happens all over the floor area. So is less dust really transported?

Natural convection convectors work on the principle of convection and can also raise dust, but dust can only arise from heat exchangers with an area 50 to 100 times smaller than the surface area of ​​the heated floor in the same room. Therefore, the amount of dust that can arise is the same number of times smaller.

Konveka forced convection convectors (with fans) has air filters, so not only does it not raise dust, but, on the contrary, reduces its concentration in rooms.

Can dust get into the convectors?

Dust mostly consists of particles of dead human skin and fibers of textile products (clothes, upholstered furniture, carpets, curtains, etc.) and mostly accumulates in sleeping beds, wardrobes, sofas, carpets, curtains. Part of it settles on all horizontal surfaces in the house, including on the upper part of convectors. However, convectors are installed near windows, where dust usually accumulates much less. These areas are easily accessible and cleaned along with the floor. If the amount of dust inside the convectors increases, they can be simply vacuumed with a vacuum cleaner once every six months to a year.

 

Can convectors raise dust?

Yes, it can, but only the dust that has settled on their heat exchangers. In this case, the air rises only when the convector heats (convectors do not heat all the time, only when needed) and only above its heat exchanger, the area of which is 50-100 times smaller than the surface area of the heated floor installed in the same room.

Some convectors have fans that further activate air movement, but Konveka fan convectors have air filters that clean the air of dust, reducing its concentration.

 

Convectors should not be confused with air conditioners, which has very noticeable airflow. The air flow caused by built-in convectors with fans cannot be felt in the room, because it is always directed towards the window, goes up to the ceiling, expands to the sides and finally descends gently as it moves along the ceiling (see Figure 1).

Figure 1: FH4-H Convector air speed distribution in the room, when the convector is working at maximum power

 

 

During this "journey", it loses most of its speed and, when the convector is working at full power, its speed in the room is less than 0.1 m/s (the maximum air speed in living rooms is 0.15 m/s specified in Lithuanian hygiene standards). Such air speed is clearly insufficient to lift dust from the surfaces, and due to its direction - from top to bottom - the dust, on the contrary, is pushed down more.

 

Thus, the claim that convection heating devices carry dust is greatly exaggerated.

 

As for dust circulation in general, it should be mentioned that the simple opening and closing of doors, walking, dressing, ventilation, and other human activities cause much greater dust circulation than any heating device. People allergic to dust successfully deal with the very causes of dust: they do not open windows during the dry season, choose materials that emit less dust, change bed linen more often and, of course, clean the rooms more often.

 

Currently, it’s a fairly common opinion that underfloor heating is the best heating method when the building's heat source is a heat pump.

 

Underfloor heating is, of course, one of the choices for heating methods when the heat source is a heat pump, but it cannot be considered the best because:

 

     1. Underfloor heating, making good use of the efficiency of heat pumps, uses the received energy extremely uneconomically (20 - 30% less efficiently than convectors and fan coils).

 

     2. Heat pumps can produce not only heat, but also cold. Underfloor heating cannot cool rooms safely, sufficiently and comfortably, and therefore cannot be used as a cooling device.

A heating system with a heat pump works most economically, while maintaining maximum comfort, if:

1. The maximum efficiency of the heat pump is used.

2. The heat obtained from the heat pump is used economically, heating only when needed:

a) maximum utilization of free heat obtained from human activity (household appliances and heat emitted by people) or the sun;

b) reducing the temperature in rooms when they are not in use.

 

1. How to maximize the efficiency of heat pump?

All types of heat pumps (in heating mode) work more economically the lower the temperature of the energy carrier is (hereinafter, referred to as water). In the graph on the right, we can see how the COP (coefficient of energy transformation) of heat pumps depends on the temperature of the water being prepared.

At the same outdoor temperature, the air-water heat pump works more efficiently when preparing water at 35°C than when preparing it at 45°C, i.e., produces the same amount of heat using less electricity.

So, in order to use the heat pump economically, it’s necessary to choose such heating devices that work efficiently with a low temperature of the supplied water.

Both underfloor heating and Konveka fan coils can efficiently heat rooms at very low (25 - 35°C) water temperatures. Therefore, these heating methods make the most of the efficiency of heat pumps.

 

2. How to economically use the received heat?

The produced heat is used most efficiently when it is heated according to demand, i.e., when needed and as much as needed. Only accurately-regulated heating devices can work in this way, so it’s necessary to use room thermostats with weekly programming in all heated rooms. In this way, we can:

- turn off the heating devices when the set temperature is reached;

- reduce the temperature of the rooms during the day when they are not in use.

Heating devices are also needed that quickly and accurately execute the commands of room thermostats.

Underfloor heating, due to its high inertia, cannot be switched on and off quickly, and it always takes a few hours to respond to thermostat commands, so it cannot be considered an economical way of heating.

In this article, you will find an analysis of the cost-effectiveness of underfloor heating and a comparison with convectors

 

Cooling

As we mentioned, all types of heat pumps have not only a heating but also a cooling function. In their principle of operation, they do not differ from air conditioners, which we associate only with cooling. Therefore, it would be profitable to use heat pumps not only for heating in winter, but also for cooling in summer.

 

Due to power, safety and comfort issues (read more here), we cannot use underfloor heating for indoor cooling.

 

Thus, underfloor heating cannot be considered the best heating method when the heat source is a heat pump, because:

 

     1. although it makes good use of the efficiency of heat pumps, it uses the received heat very uneconomically;

     2. cannot use the important feature of heat pumps - the ability to cool.

 

Konveka floor and wall fan coils don’t have these disadvantages. These devices are designed to work with heat pumps, so they have both heating and cooling functions. They make the most of all the possibilities of heat pumps in both winter and summer.

Convectors are one of the most widely used heating and heating-cooling devices. Konveka convectors work successfully in individual houses or apartments, hotels, restaurants, shopping centers, administrative and public buildings.

 

 A wide range of models (see table 1) allows them to be used in rooms of various purposes; from conference halls to swimming pools.

No.

Type

Purpose

Quantity of Models

Imagine

1

Allowed

Heating

432

2

Allowed

Heating / cooling

26

3

Hanging

Heating / cooling

2

4

Hanging

Heating

240

5

Under construction

Heating

576

 

Altogether

1,276

 

Table 1: Konveka model range of convectors

 

Working in a wide temperature range (from 1 to 100°C), Konveka devices work harmoniously with all heat-cold sources: all types of heat pumps, gas, liquid or solid fuel boilers, urban heat networks, etc. In addition, being one of the most efficient and economical heating-cooling devices, convectors also create the best conditions for the efficient operation of the heat-cold source.

 

In this article, we will review the main criteria for choosing convectors

Convector type selection

The most important criterion for the selection of all heating/cooling devices is their power. It must always be equal to or greater than the heat (cold) loss of the room, which is usually calculated by the designers of heating/cooling systems.

 

 As we know, heating devices must be installed in those areas of the premises where there is the greatest heat loss, i.e., under the windows, so the size of the windows and their distance from the floor determine the choice of convector type and size. Let's look at a few options.

 

1. Floor-to-ceiling windowPaveikslėlis, kuriame yra vidinis, langasAutomatiškai sugeneruotas aprašymas

 

In this case, 85% of customers choose convectors built into the floor because they not only heat/cool the room efficiently, but also do not block the light and view from the window, do not obstruct the opening of the balcony door, and have a clear passage.

 

In the table 2, all Konveka built-in convectors are divided into 3 groups.

Table 2: Konveka built-in convector model range

 

Group 1 - built-in natural convection FC floor convectors. These are built-in convectors with the lowest thermal power, but in the event that the building's heat source can generate a higher temperature of the heat carrier (up to 75°C), their power is usually sufficient to heat modern buildings (with energy efficiency class higher than C). That is why this model is the most popular of all built-in convectors.

The Konveka range includes 396 FC models with dimensions:

lengths - from 80 to 500 cm;

widths - 22, 32 and 42 cm;

heights - from 9 to 45 cm.

FC has no fans, so it doesn't make any sound at all; they are guaranteed to last for 10 years.

Read more about using these models here.

 

Group 2 - built-in forced convection floor FH convectorsThese convectors develop sufficient power for room heating even when working with low heat carrier temperatures, so they are particularly suitable for working with condensing boilers or heat pumps, making maximum use of their efficiency.

There are 36 FH models of convectors with dimensions:

lengths - from 85 to 300 cm;

widths - from 17 to 26 cm;

heights - 7.5 and 8.5 cm.

As their height is low, the FH easily fits into any floor structure.

One of their biggest advantages is the extremely low level of emitted sound. If the model is chosen correctly, the sound of FH is almost inaudible, so they can easily be installed in bedrooms.

Read more about the selection and use of FH models here.

 

Group 3 - built-in forced convection FCH and FCHV floor convectors. These convectors are designed to work with heat pumps - they have both heating and cooling capabilities. Like FH, they develop a high thermal capacity at low temperatures of the heat carrier, so heat pumps, working together in one system, achieve the highest efficiency.

The Konveka range includes 10 FCH and FCHV models. Their ability to cool extends the use of heat pumps from just winter to all-year round. In this way, using the same heating/cooling source, the same system and the same devices, the temperature comfort of the rooms is ensured throughout the year and the need to install air conditioners is eliminated.

FCH and FCHV, like FH, are equipped with the quietest EC type fans, so they work very quietly. Condensate baths as standard with these convectors allow them to work with very low temperature refrigerant (below the dew point).

FCHV models have the option of connecting supply air ducts. This allows the air supply ducts of the ventilation system to be installed in the floor together with the pipes and electric cables. In this case, ducts do not need to be installed in the ceiling of the room - the height of the room increases.

Dimensions of both models: 

Model

Length, cm

Width, cm

Heigth, cm

FCH

120 - 300

32

13

FCHV

120 - 300

36

15

 

Read more about the selection and use of FCH models here.

 

There are cases when the desired model of a built-in convector cannot be adapted due to existing conditions. For example, a natural convection FC convector would be enough to heat a room, but its height is greater than the possible depth in the floor structure, so a lower forced convection FH model should be chosen. Below we will discuss the main limitations on the dimensions of built-in convectors.

 

Depth. Since they are completely sunken into the floor (their top coincides with the top of the floor covering), we need to decide how deep we can sink them into the floor layer. Based on this, we choose the height of the convector. This is important because the height of the convector often determines its power. The installation depth of Konveka built-in convectors coincides with their nominal height (there is no need to provide additional height for the legs), so their height can be chosen equal to or slightly lower than the height of the floor structure (distance from the ceiling to the top of the floor covering).

 

Length. There are 2 installation options for built-in convectors: between the window edges and behind them.

After choosing option 1, the length of the convector should be chosen 20 - 30 cm smaller than the distance between the edges of the openings. During installation, the same distance of 10 - 15 cm of the convector body from the window and from both edges of the opening is left.

When option 2 is selected, the length of the convector can be equal to or greater than the distance between the edges of the openings. In this case, the case is moved away from the wall by 10-15 cm.

 

Width. The selected width is usually determined by the aesthetic aspect: narrower convectors look more elegant and concise. Therefore, if narrower convectors produce sufficient power for heating and cooling rooms, they are a better choice.

 

 

Although the majority of customers choose floor-mounted convectors for rooms where the window extends from the floor, some of them prefer standing SC and SC-H convectors.

Paveikslėlis, kuriame yra grindys, langas, vidinis, pastatasAutomatiškai sugeneruotas aprašymas

SC and SC-H are natural convection heating devices, but their power is usually sufficient even for buildings of medium and low energy class if the heat source develops a high temperature of the heat carrier (up to 75°C). These convectors will heat buildings of a high energy class even at a lower temperature, e.g. 45°C.

 

The Konveka range includes 288 SC and 288 SC-H models with dimensions:

lengths - from 60 to 290 cm

widths - 15, 20 and 25 cm

heights - from 14,5 to 33 cm.

As we can see, the lowest SC and SC-H models are 14.5 cm high, so they almost do not block the light and the view from the window, but they will interfere with opening the balcony door and with having a clear passage. Their color can be adapted to the color of window frames or walls, maximally matching the interior. With no fans, they don't make any noise at all, but they have no cooling capability.

 

As for the selection of the dimensions of the built-in convectors, it should be noted that the main limitation here is the length of the devices

Length. Convectors of this type are usually installed in window niches. Their length is selected according to the distance between the edges of the window opening, leaving at least 20 cm from the side of the thermostatic head and 10 cm from the opposite side. In this way, after placing the thermostatic head, which is about 10 cm long, the device is nicely centered between the edges of the openings.

 

The width and height are usually chosen to be minimal, but sufficient to achieve the required power

 

 

2. The height of the bottom of the window (or window sill) is 10-40 cm.

Paveikslėlis, kuriame yra vidinis, grindys, langas, gyvenimasAutomatiškai sugeneruotas aprašymasIn this case, the most suitable built-in convectors are SC and SC-H. Their heights vary from 14.5 to 33 cm, so they can be adjusted to the required height of the windowsill, leaving similar gaps from the floor and from the windowsill.

To avoid inconvenience when cleaning the floor around the appliances, you can choose the suspended version of the built-in convectors SC-W. In this case, connecting the heat carrier pipes from the wall avoids any interface between the device and the floor and leaves a completely free space for cleaning the floor

Also, rooms with windowsills of this height usually do not have opening edges, so they do not limit the length of the devices. In this way, the dimensions of the built-in convectors are chosen taking into account only the required power and aesthetics.

 

 

3. The height of the bottom of the window (or windowsill) is 50-90 cm.

With windowsills of this height, we usually choose WMC and WMCF hanging convectors. Since these devices are sufficiently different in terms of use, we will consider them separately.

WMC. These are natural convection convectors intended for heating only. They are similar to built-in convectors in terms of their operation principle and application possibilities: their power is sufficient for buildings of medium and low energy class, if the heat source generates a high temperature of the heat carrier (up to 75°C) and for buildings of high-energy class at a lower temperature, e.g. 45°C, for the temperature.

There are a total of 240 WMC models with dimensions of:

Lengths - from 60 to 200 cm;

Widths - from 8 to 23 cm;

Heights - from 30 to 60 cm.

A wide selection of heights allows them to be adapted to the existing height of the windowsills, leaving similar gaps from the floor and windowsills. It’s important to ensure a distance of at least 10 cm from the floor to the convector body for free air flow.

The length of the WMC is usually chosen based on the required power, often in combination with the window length. Connecting the pipes can be done from the floor or from the wall, hiding them behind the casing.

 

WMC doesn’t have fans, so it does not make any noise at all, and its color can be matched to the color of the interior elements.

 

 

WMCFs are powerful devices for space heating and cooling. Like FCH, they are designed to work with heat pumps: they develop a high thermal capacity at low temperatures of the heat carrier, so heat pumps, working together in one system, develop the highest efficiency.

There are 2 models of WMCF: their lengths are 150 and 110 cm, height 54 cm, thickness 16 cm.

They are also equipped with EC-type fans, so they work very quietly. Condensate baths as standard with these convectors allow them to work with very low temperature refrigerant (below the dew point).

Pipe connections, like WMC models, can be made from the floor or from the wall, hiding them behind the casing.

Read more about the selection and use of WMCF modelshere.

Customers

Customer reviews

  • Thank you KONVEKA for your professionalism and efficiency at work. You are a reliable business partner with great expertise in your field.
    We would like to sincerely thank you for your concern for our partners, to whom you always provide help and support.
    On behalf of our customers, we thank you for the quality, efficiency and aesthetics of our products.


     

    Distribution company Kazakhstan
  • We have chosen “Konveka” convectors as the main heating devices in three class A office buildings. The heating system installation works were performed in these buildings and we are satisfied with the choice because the manufacturer not only delivered the ordered heating devices in time but also complied with all special requirements stated by the builder: the colour of the convectors was matched to the colour of the building facade elements and special connecting pipe coverings were supplied. During two years of usage of the building we had no complaints about “Konveka” convectors.

    CEO at Installing Company Lithuania
  • We are partners with Konveka since 2017. Since then this manufacturer not only developed many new convector models, but also improved the existing ones. 

    We are pleased with the productivity and engineering-creative potential of Konveka specialists. All of their products are certified according to EU standards, which greatly helps us to sell them. 

    We can count on quality products, specialists who are always open to dialogue, and a fair pricing policy. We are very happy and comfortable working with a global leader in our industry. 

    Sales Representative Central Asia
  • We have been working with Konveka for about a year. Thanks to remote trainings, and their visit to Georgia, we were convinced that Konveka convectors are very high quality. While working with such product, we are confident that both parties: installers and the final consumer will be satisfied with the product.

    Showing a sample of a convector to a customer, doesn’t take a long time to convince about the quality of the proposed product. The convector speaks for itself. During the demonstration of the sample, both experts in this field and not, notesits functional and visual advantages in comparison with similar products of competitors presented on our market.

    It is also very important that Konveka employees are very reliable partners, you can contact them with any technical questions, or when advice is needed. They are always very quick with competent answers, advice and solutions.

    At last, a very important factor is the competitive price. We are sure that the price that Konveka offers us is always adequate and competitive. And if there is some kind of reference project or we need a price from our partner for a tender or to fight competitors, then we know that even here we will not be left alone on the battlefield and Konveka will try to do everything for a specific project to support us. And we really appreciate it!

    On the whole, we are very glad that we have such a partner. 

    CEO at Distribution company Georgia
  • Pleasure to work with you. 

    Proposals submitted promptly, optimal option is always found. Problems and issues are resolved in a timely manner.

    We are positive with continuing our smooth cooperation. 

    Deputy Director at construction company Lithuania
  • Konveka as a supplier is one that always give good and fast response. They are very knowledgeable in convectors and their products and when working with them you understand that they have thought of all aspects in their product development. Also when facing projects with special needs, Konveka is very supportive and can bring forward new designs that will fit those needs.

    Managing Director at Distribution company Sweden
  • Our company would like to sincerely thank to Konveka for its quality products and timely production of convectors. Your timely produced and shipped orders have allowed us to run our business smoothly.
    We believe in the continued maintenance of the existing friendly relations and further mutually beneficial and fruitful cooperation.

    Distribution company
  • Solid company. Fast execution of orders and suitable delivery times to Ukraine.

    I recommend visiting their factory! Wide selection of heating and cooling devices.

    Quality advice and excellent support for large projects at all stages. In the case of exceptional projects, non-standard solutions are found. Managers does a great job.

    My respect for the company and evaluation 5/5.

    Manager at Distribution company Ukraine
  • This isn't the first time we've bought and installed Konveka‘s products and we are very pleased. Excellent quality, professional approach and best production terms.

    Konveka employees always respond quickly to our inquiries, provide professional technical support and easily find solutions in non-standard situations.

    Procurement Specialist at Installing Company Latvia