Hello everyone, I have been looking for answers in many places but nowhere have I found anything satisfactory. I would also like to add that I do not know the subject in any particular way. This year, the mother-in-law changed to gas heating. Apartment (48 meters, 2 rooms + kitchen + bathroom +...

By peasant reason. It's just that frequent boiler starts can use more gas than continuous low-power operation, not to mention the faster wear of the boiler. Unfortunately, boilers almost always have too high minimum power (especially in the current climate - instead of winters, there are only several-day winter episodes, e.g. 3-5 winter days in December (max. Seven), 7 winter days in January (sometimes 10) and 3 -5 winter days in February (and sometimes in February there is not a single day with winter temperature, e.g. February 2016 and 2019). With better and better thermal insulation of buildings, this minimum power must be really low, so that the boiler does not have to constantly clock (for most of the season it is completely unrealistic, unless we want to make a sauna inside). There are, however, two contradictions. Namely, the flow heating of water to the bathroom requires a lot of power, hence the combined boiler should have a maximum power of about 24kW (this is what the larger Junkers) to ensure the comfort of taking hot water, otherwise there must be a storage tank, which takes up a lot of space and is not so economical.

Assuming that the first value is the height of the radiator and the second value is its length, you have type 22 radiators with 2 heights of 40 and 60 cm. According to the Kermi catalog, for a temperature of 75/65 it is 1m of a type 22 radiator with a height of: 40cm has a power of 1207W 60cm has a power of 1666W So for 75/65/20: - the hall is 666W - 833W kitchen - room1 has 2 * 1690W = 3380W - room2 has 2 * 1690W = 3380W TOTAL 8259W In practice, 75/65 is usually a theoretical value, so for my calculations I assume that we heat the water to 70 degrees to the maximum and we will have 50 on the return. The Kermi catalog gives a factor of 1.37. 8259W / 1.37 = 6028W. In other words, the maximum power of your heaters for 70/50 boiler water is 6kW, not counting the bathroom ladder. For the boiler water 60/45 we have a factor of 1.78, which means that then your radiators offer 4.6 kW. For 55/45 boiler water we have a factor of 1.96, which gives a power of 4.2 kW. For 50/40 boiler water we have a factor of 2.50 which gives a total power of 3.3 kW. For 40/35 boiler water we have a factor of 3.93, which gives a power of 2.1 kW. Since your boiler has a minimum power of 4.3kW, in theory, only with boiler water 60/45 the power of your radiators will exceed the minimum boiler power, i.e. in theory at approx. 60 degrees on the supply, your boiler will be able to heat water non-stop without the need to further raise the water temperature boiler, provided that all radiators are open to the maximum. This is a better situation than mine, looking at the ratio of the heaters' power to the minimum boiler power. But when I had your boiler with a minimum power of 4.3kW, my 50/35 heaters for boiler water have 4.3kW, so in theory, already at about 50-55 degrees on the power supply, I could get the boiler to work continuously, so I would have a better situation than yours . Based on this, you have a better idea of what to expect from your boiler and your installation. Added after 10 [minutes]: for all this, you have to take into account the real heat demand. If we assume, for example, 85W / m2, then we have a total of 4kW for frosts -20, i.e. on average during the season you will need approx. 2kW of constant power. Your heaters offer 2.1kW with 40/35 boiler water, but your boiler has a power of 4.3kW, so it will not be able to maintain a constant temperature of 40 degrees on the supply. Single-function boilers offer a minimum power of 2.2-2.3kW, then in theory you could maintain a constant 40 degrees of power on the boiler and the feeling of comfort would be better than at present. With the current boiler, you have to heat the water to higher temperatures, which means cyclical overheating of the rooms and then a break so that the water cools down and the boiler can provide another portion of energy. Since the heated radiators will still be warm for a dozen or so minutes, you have to take it into account in your settings, then you can try to lower the temperature of the boiler water set on the boiler. But you have to remember that when the outside temperature drops, you may need to raise it a few degrees. You have to play yourself and look for the optimal settings for your installation and your feeling of thermal comfort. Added after 15 [minutes]: and you must take into account the break in the burner operation that your boiler allows. In my boiler, at approx. 58 degrees, the burner lockout can be approx. 30 minutes, so it is enough to wait until, for example, in the next 10-15 minutes, the temperature in the room will increase by a few tenths of a degree and the room regulator will turn off the heating. I don't remember what burner lockouts your boiler has, so you would have to keep that in mind. I try to use all the possibilities that my boiler gives me. They are not extensive but I know what it allows me to do.

What kind of radiators are they? Cast iron? Because that would explain the sine wave with the valves on the radiators fully open. Such heaters have a large water capacity, and thus also thermal inertia. After warming up, they give the heat back to the apartment for a long time, cooling down. What was good in, for example, a coal boiler is not entirely perfect with gas boilers. The gas boiler, in my opinion, works better with aluminum or panel radiators, there are minimal temperature fluctuations with radiators with a small water capacity. A gas boiler usually does not work non-stop (unlike a coal-fired one), only in cycles, especially in apartments. By turning off the valves on the radiators a little, you throttled the flow through the radiators. They heat up more slowly, so when the boiler is turned off, they are not all hot, so there is no big effect of overheating the apartment. Yes, the longer operation of the condensing boiler is more economical. As for the boiler temperature, I would try to reduce it by a few degrees, e.g. to 45. There are 2 advantages to this and 2 potential disadvantages: - the Termet boiler has a low minimum power, so it will probably work longer at 45 degrees, not overheating the boiler water (without tapping the burner), which extends the life of the boiler and very slowly increases the temperature in the apartment (even smaller fluctuations, greater comfort) - better combustion economy, at a lower central heating supply temperature (and therefore also return), the boiler has better efficiency (you can gain 2% savings) because there is more intense heat recovery from condensation) - the first downside is that if you set it to e.g. 45 degrees, if it will be -10 outside, it may not be enough and you will have to raise it to e.g. 50-55 degrees in frost - the second disadvantage is that the minimum power of the boiler must be at least equal to or lower than the power of the radiators at a given temperature. You have to check it organoleptically or count it. If you set, for example, 45 degrees and the boiler, for example, working 40 minutes, it will turn off the burner in the boiler (despite the fact that the room regulator will continue to demand heat) because the boiler will not be able to maintain 45 degrees, but it will slowly overheat the CO water to e.g. 50 degrees), i.e. the power radiators is too small in relation to the minimum boiler power at the set temperature.

I assume that someone counted it by choosing such and not other elements of the installation, and did not choose Pi times the Eye - but in real life it is what is. In fact, I do not have much experience with such small heating installations, but in such a situation, by way of an experiment - on throttled radiators, I would increase the intensity of the medium flow through the boiler, this should slow down the temperature rise in the boiler. Later, after a possible positive effect, I would adjust the temperature in the rooms by appropriately adjusting the nut setting on the radiators.

I assume that the entire installation is after the old boiler and only the boiler was replaced, so nothing was counted too much. The boiler has a minimum capacity of 3kW, so it is a very good minimum for an apartment. And since it is a dual-function boiler, hence the 24kW boiler. After the description of use, I suppose that the current radiators are cast iron. Typical symptoms, on hot radiators, the regulator turns off the boiler, and heaters with high heat capacity continue to heat up for another half an hour. 46m with large heat losses (as he wrote, it cools down quickly), it may be around 7kW in frosts minus 20. At around 0 degrees outside, it should be over 3kW, which is slightly less than the minimum power of the boiler. So there is a chance for continuous work for a certain part of the winter. The easiest way to reduce the current power of the radiators is to lower the temperature in the boiler.

I would calculate the heating power of the radiators so that it was equal to the minimum boiler power, e.g. 4.3 kW at 50/30 temperature. If these are cast iron radiators, then a calculator, e.g. So, the operation of the gas boiler is normal. For me, the temperature at aluminum radiators increases by 0.3 degrees after turning off the boiler above the set temperature. When the temperature on the boiler is lowered so that it will operate below the minimum, the radiators will be warm, there will be better thermal comfort, but the boiler will clock (frequent switching on / off) and the pump will run non-stop, consuming electricity. So bad and so bad

Since I have not dealt with such small circuits and with the regulator mentioned here, I will ask what the input parameters of this regulator are (I suppose the temperature at the outlet and the temperature at the boiler inlet) and what this regulator affects - it regulates the amount of gas (flame size), or maybe it increases the flow rate of the medium through the boiler? Added after 6 [minutes]: I was supposed to ask about that, too, but forgot. It seemed to me that the circulating pump should work all the time. If periodically, what parameter causes the boiler restart.

I will straighten it a bit, the radiators are made of panels (only in the bathroom there is a ladder), the whole installation is new, made from scratch - there was a tiled stove before. So it turns out that the longer operation of the boiler is more economical, and the temperature is also more stable. If so, this is probably the most convenient and economical option. For now, I will rather not change the temperature on the boiler, because from what I can see there will be no such need and a big difference (in fact, this is only the first season with the stove, so I will see when the temperatures will be lower, how the stove behaves) The controller only measures the temperature in the room in which it is located (such a portable device) and you can set the temperature to be in the room and when it is reached, the stove turns off until the temperature is too low and turns it on again. .

I had imagined it differently. I thought that the regulator cares about maintaining the set parameters on the boiler, and that the temperature control in the rooms is individual, e.g. by thermostatic valves.

No, the room regulator, as a rule, monitors the temperature in the room where it is located (if it is a hall, the temperature is more or less the same in the whole apartment). And the thermostatic heads only refine the temperature in other rooms. Although when choosing the right power of radiators for individual rooms, the heads have little to do. I would try to lower it just to know how much I can afford. Each step down on CO (until the boiler is not able to keep the set temperature and will raise it spontaneously due to the insufficient power of the heaters) means better condensation, therefore a little cheaper and longer heating cycles (better comfort). I have a boiler with a minimum power of 5.2 kW at 67 meters and 80 aluminum fins (and thermostatic heads). I have a set of 48 degrees for autumn temperatures and mild frosts (the boiler maintains 48 degrees during an hour of operation, or even reaches 50 degrees, which does not, however, turn the burner off). When it gets colder, I raise it to e.g. 50 degrees (last year I had max -10 frosts, if it will be from -20 I will raise it to e.g. 55). Now the question is why am I doing this, in the sense why I keep the CO temperature as low as possible? I already wrote, comfort and economy. Comfort because the radiators are warm almost non-stop (but not hot), the boiler also works with the longest cycles, and economy because the lower you can supply the radiators, the better the condensation. If I had a boiler, e.g. Termeta 20kW with a minimum of 3kW, it was in my apartment and my battery of radiators, I could also think about weather control. And for temperatures around 5 outside, the heaters could be powered by 40 degrees 24 / h.

Wojewoda82 he has a 25 kW model with a minimum power of 4.3 kW at 50/30 ( I have 106 ribs and a minimum power of 9.5 kW. With the parameters 66/56/21, the radiators have a similar power. If I set 50 degrees, the boiler heats up for an hour and then it will raise the temperature by these 5 degrees and clock it.

So if I understand correctly, the uninterrupted operation of such a boiler is the most desirable situation? By the peasant's understanding, it seems that the gas consumption for such work will be higher.

[Solved] Title: Efficient Gas Heating: Termet EcoCondens Silver 25 & Salus 091flrf Radiator Settings Guide

Cypu87 42573 17

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How should I set the radiator valves and boiler temperature on a Termet EcoCondens Silver 25 with a Salus 091flrf to avoid overheating and run the system economically?

For this boiler, the most economical setup is usually a lower supply temperature with the radiators opened just enough to avoid big room-temperature swings, because longer low-power cycles and better condensation are more efficient than short hot cycles [#18354081][#18371951] The practical advice was to try lowering the central-heating temperature from 50°C to around 45°C and then raise it only if the apartment cannot keep up in colder weather; if the boiler cannot hold the set temperature, it will start short-cycling instead [#18354081][#18354304] Your Termet EcoCondens Silver 25 has a minimum heating power of 4.3 kW, so the key is whether the radiators can absorb at least that much at the chosen water temperature [#18372141][#18376593] For the listed Kermi panel radiators, the estimated total output is about 6 kW at 70/50, 4.6 kW at 60/45, 4.2 kW at 55/45, and 3.3 kW at 50/40, so around 60/45 is the first range where the radiator power roughly matches the boiler minimum and steadier operation becomes realistic [#18376593] Since the room regulator only measures the room where it is placed, radiator valves should be used as fine adjustment in the other rooms, not as the main control method [#18355241] If the apartment is already comfortable, there is no need to change everything at once; the safest approach is to test a slightly lower boiler temperature and observe how the boiler behaves on colder days [#18355241][#18376593]

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#1 18353896 21 Dec 2019 23:53

Cypu87 Cypu87

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18353896 21 Dec 2019 23:53

Hello everyone, I have been looking for answers in many places but nowhere have I found anything satisfactory. I would also like to add that I do not know the subject in any particular way.
This year, the mother-in-law changed to gas heating. Apartment (48 meters, 2 rooms + kitchen + bathroom + hall) in a one-story tenement house on the first floor with quite high heat losses (it cools down quickly). Termet EcoCondens Silver 25 gas oven combined with the Salus 091flrf heat regulator. I am interested in your views on appropriate radiator settings. Until recently, all radiators in the apartment were set to the maximum value (there are no thermostats on the radiators, only the caps - in this case unscrewed all the way) on the regulator, the temperature is set to 20 ° C and the stove worked irregularly (I would say strongly sinusoidal), i.e. the radiators became very hot, so the temperature before it "reached" the regulator significantly exceeded 20 ° C, then it cooled down and when the temperature dropped, the furnace turned on again - as a result, it was once too hot, then it gradually cooled down and then too hot again and over and over again. In such a case, the furnace worked for a short time (the radiators quickly filled the temperature). I decided to tighten the radiators significantly so that they do not heat up with full power, which makes the stove work longer, but the temperature does not exceed the expected value (it does not heat up hotter than we want) and it seems that it is a more stable solution (at least in terms of the perceived temperature). Now the question is, is this setting economical? Overall, the stove works with a similar power (if not the same), but for a much longer time. Finally, I can add that the temperature transferred to the radiators set on the stove is 50 ° C (the master who installed the stove recommended this).

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#2 18354081 22 Dec 2019 08:48

Wojewoda82 Wojewoda82

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18354081 22 Dec 2019 08:48

What kind of radiators are they? Cast iron?

Because that would explain the sine wave with the valves on the radiators fully open. Such heaters have a large water capacity, and thus also thermal inertia. After warming up, they give the heat back to the apartment for a long time, cooling down. What was good in, for example, a coal boiler is not entirely perfect with gas boilers. The gas boiler, in my opinion, works better with aluminum or panel radiators, there are minimal temperature fluctuations with radiators with a small water capacity.

A gas boiler usually does not work non-stop (unlike a coal-fired one), only in cycles, especially in apartments.

By turning off the valves on the radiators a little, you throttled the flow through the radiators. They heat up more slowly, so when the boiler is turned off, they are not all hot, so there is no big effect of overheating the apartment.

Yes, the longer operation of the condensing boiler is more economical.

As for the boiler temperature, I would try to reduce it by a few degrees, e.g. to 45. There are 2 advantages to this and 2 potential disadvantages:
- the Termet boiler has a low minimum power, so it will probably work longer at 45 degrees, not overheating the boiler water (without tapping the burner), which extends the life of the boiler and very slowly increases the temperature in the apartment (even smaller fluctuations, greater comfort)
- better combustion economy, at a lower central heating supply temperature (and therefore also return), the boiler has better efficiency (you can gain 2% savings) because there is more intense heat recovery from condensation)
- the first downside is that if you set it to e.g. 45 degrees, if it will be -10 outside, it may not be enough and you will have to raise it to e.g. 50-55 degrees in frost
- the second disadvantage is that the minimum power of the boiler must be at least equal to or lower than the power of the radiators at a given temperature. You have to check it organoleptically or count it. If you set, for example, 45 degrees and the boiler, for example, working 40 minutes, it will turn off the burner in the boiler (despite the fact that the room regulator will continue to demand heat) because the boiler will not be able to maintain 45 degrees, but it will slowly overheat the CO water to e.g. 50 degrees), i.e. the power radiators is too small in relation to the minimum boiler power at the set temperature.
#3 18354143 22 Dec 2019 09:43

gimak gimak

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18354143 22 Dec 2019 09:43

Wojewoda82 wrote:
If you set, for example, 45 degrees and the boiler, for example, working 40 minutes, it will turn off the burner in the boiler (despite the fact that the room regulator will continue to demand heat) because the boiler will not be able to maintain 45 degrees, but it will slowly overheat the CO water to e.g. 50 degrees), i.e. the power radiators is too small in relation to the minimum boiler power at the set temperature.

I assume that someone counted it by choosing such and not other elements of the installation, and did not choose Pi times the Eye - but in real life it is what is. In fact, I do not have much experience with such small heating installations, but in such a situation, by way of an experiment - on throttled radiators, I would increase the intensity of the medium flow through the boiler, this should slow down the temperature rise in the boiler. Later, after a possible positive effect, I would adjust the temperature in the rooms by appropriately adjusting the "nut" setting on the radiators.
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#4 18354304 22 Dec 2019 11:13

Wojewoda82 Wojewoda82

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18354304 22 Dec 2019 11:13

I assume that the entire installation is after the old boiler and only the boiler was replaced, so nothing was counted too much. The boiler has a minimum capacity of 3kW, so it is a very good minimum for an apartment. And since it is a dual-function boiler, hence the 24kW boiler.

After the description of use, I suppose that the current radiators are cast iron. Typical symptoms, on hot radiators, the regulator turns off the boiler, and heaters with high heat capacity continue to heat up for another half an hour.

46m with large heat losses (as he wrote, it cools down quickly), it may be around 7kW in frosts minus 20. At around 0 degrees outside, it should be over 3kW, which is slightly less than the minimum power of the boiler. So there is a chance for continuous work for a certain part of the winter. The easiest way to reduce the current power of the radiators is to lower the temperature in the boiler.
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#5 18354720 22 Dec 2019 14:24

TomekO1976 TomekO1976

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18354720 22 Dec 2019 14:24

I would calculate the heating power of the radiators so that it was equal to the minimum boiler power, e.g. 4.3 kW at 50/30 temperature. If these are cast iron radiators, then a calculator, e.g. https://www.purmo.com/pl/produkty/calculator-2.htm

So, the operation of the gas boiler is normal. For me, the temperature at aluminum radiators increases by 0.3 degrees after turning off the boiler above the set temperature. When the temperature on the boiler is lowered so that it will operate below the minimum, the radiators will be warm, there will be better thermal comfort, but the boiler will clock (frequent switching on / off) and the pump will run non-stop, consuming electricity. So bad and so bad
#6 18354846 22 Dec 2019 15:34

gimak gimak

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18354846 22 Dec 2019 15:34

Since I have not dealt with such small circuits and with the regulator mentioned here, I will ask what the input parameters of this regulator are (I suppose the temperature at the outlet and the temperature at the boiler inlet) and what this regulator affects - it regulates the amount of gas (flame size), or maybe it increases the flow rate of the medium through the boiler?

Added after 6 [minutes]:

TomekO1976 wrote:
and the pump will run non-stop using electricity.

I was supposed to ask about that, too, but forgot. It seemed to me that the circulating pump should work all the time. If periodically, what parameter causes the boiler restart.
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#7 18354898 22 Dec 2019 16:00

Cypu87 Cypu87

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18354898 22 Dec 2019 16:00

I will straighten it a bit, the radiators are made of panels (only in the bathroom there is a "ladder"), the whole installation is new, made from scratch - there was a tiled stove before. So it turns out that the longer operation of the boiler is more economical, and the temperature is also more stable. If so, this is probably the most convenient and economical option. For now, I will rather not change the temperature on the boiler, because from what I can see there will be no such need and a big difference (in fact, this is only the first season with the stove, so I will see when the temperatures will be lower, how the stove behaves)

The controller only measures the temperature in the room in which it is located (such a portable device) and you can set the temperature to be in the room and when it is reached, the stove turns off until the temperature is too low and turns it on again. .
#8 18355132 22 Dec 2019 17:45

gimak gimak

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18355132 22 Dec 2019 17:45

Cypu87 wrote:
The controller only measures the temperature in the room in which it is located (such a portable device) and you can set the temperature to be in the room and when it is reached, the stove turns off until the temperature is too low and turns it on again. .

I had imagined it differently. I thought that the regulator cares about maintaining the set parameters on the boiler, and that the temperature control in the rooms is individual, e.g. by thermostatic valves.
#9 18355241 22 Dec 2019 18:17

Wojewoda82 Wojewoda82

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18355241 22 Dec 2019 18:17

No, the room regulator, as a rule, monitors the temperature in the room where it is located (if it is a hall, the temperature is more or less the same in the whole apartment). And the thermostatic heads only refine the temperature in other rooms.

Although when choosing the right power of radiators for individual rooms, the heads have little to do.

Cypu87 wrote:
For now, I will rather not change the temperature on the boiler, because from what I can see there will be no such need and a big difference (in fact, this is only the first season with the stove, so I will see when the temperatures will be lower, how the stove behaves)

I would try to lower it just to know how much I can afford.

Each step down on CO (until the boiler is not able to keep the set temperature and will raise it spontaneously due to the insufficient power of the heaters) means better condensation, therefore a little cheaper and longer heating cycles (better comfort).

I have a boiler with a minimum power of 5.2 kW at 67 meters and 80 aluminum fins (and thermostatic heads). I have a set of 48 degrees for autumn temperatures and mild frosts (the boiler maintains 48 degrees during an hour of operation, or even reaches 50 degrees, which does not, however, turn the burner off).

When it gets colder, I raise it to e.g. 50 degrees (last year I had max -10 frosts, if it will be from -20 I will raise it to e.g. 55).

Now the question is why am I doing this, in the sense why I keep the CO temperature as low as possible? I already wrote, comfort and economy. Comfort because the radiators are warm almost non-stop (but not hot), the boiler also works with the longest cycles, and economy because the lower you can supply the radiators, the better the condensation.

If I had a boiler, e.g. Termeta 20kW with a minimum of 3kW, it was in my apartment and my battery of radiators, I could also think about weather control. And for temperatures around 5 outside, the heaters could be powered by 40 degrees 24 / h.
#10 18355348 22 Dec 2019 18:57

TomekO1976 TomekO1976

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18355348 22 Dec 2019 18:57

Wojewoda82 he has a 25 kW model with a minimum power of 4.3 kW at 50/30
(https://www.termet.com.pl/pl/produkt/ecocondens-silver/66).

I have 106 ribs and a minimum power of 9.5 kW. With the parameters 66/56/21, the radiators have a similar power. If I set 50 degrees, the boiler heats up for an hour and then it will raise the temperature by these 5 degrees and clock it.
#11 18371761 31 Dec 2019 13:55

Cypu87 Cypu87

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18371761 31 Dec 2019 13:55

Wojewoda82 wrote:
So there is a chance for continuous work for a certain part of the winter.

So if I understand correctly, the uninterrupted operation of such a boiler is the most desirable situation? By the peasant's understanding, it seems that the gas consumption for such work will be higher.
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#12 18371951 31 Dec 2019 15:28

Zbigniew Rusek Zbigniew Rusek

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18371951 31 Dec 2019 15:28

Cypu87 wrote:

Wojewoda82 wrote:
So there is a chance for continuous work for a certain part of the winter.

So if I understand correctly, the uninterrupted operation of such a boiler is the most desirable situation? By the peasant's understanding, it seems that the gas consumption for such work will be higher.

"By peasant reason". It's just that frequent boiler starts can use more gas than continuous low-power operation, not to mention the faster wear of the boiler. Unfortunately, boilers almost always have too high minimum power (especially in the current climate - instead of winters, there are only several-day winter episodes, e.g. 3-5 winter days in December (max. Seven), 7 winter days in January (sometimes 10) and 3 -5 winter days in February (and sometimes in February there is not a single day with winter temperature, e.g. February 2016 and 2019). With better and better thermal insulation of buildings, this minimum power must be really low, so that the boiler does not have to constantly "clock" "(for most of the season it is completely unrealistic, unless we want to make a sauna inside). There are, however, two contradictions. Namely, the flow heating of water to the bathroom requires a lot of power, hence the combined boiler should have a maximum power of about 24kW (this is what the larger Junkers) to ensure the comfort of taking hot water, otherwise there must be a storage tank, which takes up a lot of space and is not so economical.
#13 18372141 31 Dec 2019 16:51

BUCKS BUCKS

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18372141 31 Dec 2019 16:51

Cypu87 wrote:
Apartment (48 meters, 2 rooms + kitchen + bathroom + hall) in a one-story tenement house on the first floor with quite high heat losses (it cools down quickly).

Assuming the demand of e.g. 100W / m2, this gives the demand for a constant power of 4.8kW for frosts at the level of -20, and on average in the season it will be 2.4kW.

Cypu87 wrote:
Termet EcoCondens Silver 25 gas oven combined with the Salus 091flrf heat regulator

And that was a mistake because the Silver 25 has a minimum power of 4.3kW, and 30kW for domestic hot water.
The Silver 20 model, on the other hand, has a minimum power of 3.0kW, and the power for hot water 25kW.
Instead of adding 5kW for domestic hot water, which is unlikely to be used in such an apartment, it was better to buy a boiler with a lower minimum power. The difference in the minimum power of 1.3kW for a 48m2 apartment is a big difference.
But it is so and we have no turning back.

Cypu87 wrote:
So if I understand correctly, the uninterrupted operation of such a boiler is the most desirable situation?

it is desirable, but it is impossible for you, because the boiler has a minimum power of 4.3kW, and your heaters certainly have a lower power, so you will not avoid clocking. With the Silver 20 the clock speed would also be a bit lower due to the minimum power of 3.0kW.

We don't know what size your radiators are and what power they actually offer.
Enter the dimensions of your radiators, it will be possible to estimate their power, it will be something specific.
#14 18372403 31 Dec 2019 19:16

Wojewoda82 Wojewoda82

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18372403 31 Dec 2019 19:16

These 4.3 are not a tragedy yet, BUCKS lives with a minimum of 9KW, a friend in a new 40m2 rented apartment has Immergas Eolo Star 24 3 E with a minimum power of 11.5 kW on CO! And the radiators are tiny.
#15 18372463 31 Dec 2019 19:59

BUCKS BUCKS

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Post #15
18372463 31 Dec 2019 19:59

Wojewoda82 wrote:
These 4.3 are not a tragedy yet,

point of view depends on the point of sitting.
There is no tragedy, but it could have been better if there was a Silver 20 model. It was enough to choose a lower boiler model, but this is how the investor has no idea what water heating is all about.

Wojewoda82 wrote:
BUCKS lives with a minimum 9KW,

My boiler has a real minimum of 9.5kW, but I have a 100m2 apartment in an old, uninsulated building and the radiators have a total of 9.2kW for 70/50 boiler water.
I do not know what my real heat demand is, I can estimate that it will be, for example, 8.5 kW for frosts -20.
If the author has radiators with a total power of approx. 4.2 kW for 70/50 boiler water, it can be said that in relation to the power of the radiators to the boiler power, the situation is more or less the same as mine.
But there is still the question of the real heat demand.
And if it has heaters with a power greater than 4.2kW, it will have a proportionally better situation than mine, and if it has a power below 4.2kW, it will have a worse situation than me with the current boiler.

However, I can, in the future, change the boiler with a minimum power of 9.5kW to a new model with a minimum power of 3-4kW, so there will be a 2-fold decrease in the minimum power compared to the current state.
In the future, the author can go down to a maximum of 3kW for a 2-function boiler, so it will be a smaller percentage change than in my case.

Wojewoda82 wrote:
a friend in a new, 40m2 rented apartment has Immergas Eolo Star 24 3 E with a minimum power of 11.5 kW on CO! And the radiators are tiny.

When you rent, you come on a ready-made basis and you have no influence on the existing heating, but you can always rent another apartment. When installing at home, a bad boiler purchase stays for the next 10 years, so unfortunately it has greater consequences.

Added after 8 [minutes]:

and taking the opportunity to step on and wish you all a Happy New Year and satisfaction with the boilers and all heating, let the thermal power be with you
#16 18376167 02 Jan 2020 18:24

Cypu87 Cypu87

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Post #16
18376167 02 Jan 2020 18:24

BUCKS wrote:
Enter the dimensions of your radiators, it will be possible to estimate their power, it will be something specific.

Kermi plate radiators (I found the instruction "AKP 2017/03 6907562"):
Working pressure: max. 10 bar
Test pressure: 1.3 x working pressure
Flow temperature: heating water up to 110 ° C
Flow temperature for FTP, PTP and PLP heaters: heating water up to 90 ° C

Dimensions:
Bathroom (ladder with 14 rungs): 70x20x10 cm
Hall: 60x40x10 cm
Kitchen: 60x50x10 cm
Room 1: two heaters 40x140x10 cm
Room 2: two heaters 40x140x10 cm
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#17 18376593 02 Jan 2020 21:14

BUCKS BUCKS

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Post #17
18376593 02 Jan 2020 21:14

Cypu87 wrote:
Dimensions:
Bathroom (ladder with 14 rungs): 70x20x10 cm
Hall: 60x40x10 cm
Kitchen: 60x50x10 cm
Room 1: two heaters 40x140x10 cm
Room 2: two heaters 40x140x10 cm

Assuming that the first value is the height of the radiator and the second value is its length, you have type 22 radiators with 2 heights of 40 and 60 cm.
According to the Kermi catalog, for a temperature of 75/65 it is 1m of a type 22 radiator with a height of:
40cm has a power of 1207W
60cm has a power of 1666W

So for 75/65/20:
- the hall is 666W
- 833W kitchen
- room1 has 2 * 1690W = 3380W
- room2 has 2 * 1690W = 3380W
TOTAL 8259W

In practice, 75/65 is usually a theoretical value, so for my calculations I assume that we heat the water to 70 degrees to the maximum and we will have 50 on the return.
The Kermi catalog gives a factor of 1.37.
8259W / 1.37 = 6028W.
In other words, the maximum power of your heaters for 70/50 boiler water is 6kW, not counting the bathroom ladder.

For the boiler water 60/45 we have a factor of 1.78, which means that then your radiators offer 4.6 kW.
For 55/45 boiler water we have a factor of 1.96, which gives a power of 4.2 kW.
For 50/40 boiler water we have a factor of 2.50 which gives a total power of 3.3 kW.
For 40/35 boiler water we have a factor of 3.93, which gives a power of 2.1 kW.

Since your boiler has a minimum power of 4.3kW, in theory, only with boiler water 60/45 the power of your radiators will exceed the minimum boiler power, i.e. in theory at approx. 60 degrees on the supply, your boiler will be able to heat water non-stop without the need to further raise the water temperature boiler, provided that all radiators are open to the maximum.
This is a better situation than mine, looking at the ratio of the heaters' power to the minimum boiler power.
But when I had your boiler with a minimum power of 4.3kW, my 50/35 heaters for boiler water have 4.3kW, so in theory, already at about 50-55 degrees on the power supply, I could get the boiler to work continuously, so I would have a better situation than yours .

Based on this, you have a better idea of what to expect from your boiler and your installation.

Added after 10 [minutes]:

for all this, you have to take into account the real heat demand.
If we assume, for example, 85W / m2, then we have a total of 4kW for frosts -20, i.e. on average during the season you will need approx. 2kW of constant power.
Your heaters offer 2.1kW with 40/35 boiler water, but your boiler has a power of 4.3kW, so it will not be able to maintain a constant temperature of 40 degrees on the supply.
Single-function boilers offer a minimum power of 2.2-2.3kW, then in theory you could maintain a constant 40 degrees of power on the boiler and the feeling of comfort would be better than at present.
With the current boiler, you have to heat the water to higher temperatures, which means cyclical overheating of the rooms and then a break so that the water cools down and the boiler can provide another portion of energy.
Since the heated radiators will still be warm for a dozen or so minutes, you have to take it into account in your settings, then you can try to lower the temperature of the boiler water set on the boiler. But you have to remember that when the outside temperature drops, you may need to raise it a few degrees.
You have to play yourself and look for the optimal settings for your installation and your feeling of thermal comfort.

Added after 15 [minutes]:

and you must take into account the break in the burner operation that your boiler allows.
In my boiler, at approx. 58 degrees, the burner lockout can be approx. 30 minutes, so it is enough to wait until, for example, in the next 10-15 minutes, the temperature in the room will increase by a few tenths of a degree and the room regulator will turn off the heating.
I don't remember what burner lockouts your boiler has, so you would have to keep that in mind.
I try to use all the possibilities that my boiler gives me. They are not extensive but I know what it allows me to do.
#18 18567141 28 Mar 2020 14:12

Cypu87 Cypu87

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Post #18
18567141 28 Mar 2020 14:12

Thank you everyone, you helped me a lot
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Topic summary

✨ The discussion revolves around optimizing radiator settings for a Termet EcoCondens Silver 25 gas boiler in an apartment with significant heat loss. Users suggest that the current setup, with all radiators fully open, leads to temperature fluctuations due to the high thermal inertia of cast iron radiators. Recommendations include throttling the radiator valves to achieve more stable heating and reduce overheating. The importance of matching radiator output to the boiler's minimum power is emphasized, with suggestions to consider the use of aluminum or panel radiators for better efficiency. The Salus 091flrf regulator is noted to control room temperature, but it does not manage boiler parameters directly. Continuous operation of the boiler at lower power is deemed more economical than frequent cycling, which can lead to higher gas consumption and wear on the system.
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FAQ

TL;DR: To stop overshoot on Termet EcoCondens Silver 25 + Salus 091flrf, lower CH flow (e.g., 45°C); expect about 2% efficiency gain, and "longer operation is more economical." Balance radiator throttling to smooth heat delivery. [Elektroda, Wojewoda82, post #18354081]

Why it matters: This helps users asking how to set radiators and boiler temps for stable, efficient heating in a 48 m² flat with panel radiators.

Quick Facts

Silver 25 minimum CH power: approx. 4.3 kW (50/30); high DHW power is why this model is 25 kW. [Elektroda, TomekO1976, post #18355348]
Kermi panel radiator total output: ~6.0 kW at 70/50; ~4.2 kW at 55/45; ~3.3 kW at 50/40. [Elektroda, BUCKS, post #18376593]
Lowering flow to ~45°C can add ~2% efficiency via stronger condensation; raise to 50–55°C in frost. [Elektroda, Wojewoda82, post #18354081]
Rule-of-thumb demand for 48 m², leaky flat: ~4.8 kW peak (−20°C) and ~2.4 kW seasonal average. [Elektroda, BUCKS, post #18372141]
Salus 091flrf is an on/off room thermostat; thermostatic heads refine other rooms. [Elektroda, Wojewoda82, post #18355241]

How do I stop overheating and cooling cycles with this setup?

Open all radiators, then slightly throttle each lockshield to slow heat release. Lower boiler flow to 45–50°C. This extends burner runtime and reduces overshoot. Condensing efficiency improves too. Monitor room temperature stability and adjust in small steps. If outside temperatures drop, increase flow a few degrees. "Longer operation is more economical." [Elektroda, Wojewoda82, post #18354081]

Is running continuously actually cheaper for a condensing boiler?

Yes, continuous low-power operation can use less gas than frequent starts. Frequent starts waste fuel and wear components. Seasonal conditions often mean minimum power is too high for modern buildings. Accept some cycling, but aim for longer cycles. Prioritise stable, modest flow temperatures and good radiator balancing. [Elektroda, Zbigniew Rusek, post #18371951]

What flow temperature should I start with—50b0C or 45b0C?

Start near 45b0C in mild weather. "I would try to reduce it by a few degrees, e.g., to 45." Expect better comfort and slight efficiency gains. When it is −10b0C outside, 45b0C may be insufficient. Raise supply to 50–55b0C during frost. Ensure radiator power matches the boiler’s minimum at the chosen temperature. [Elektroda, Wojewoda82, post #18354081]

Will my Silver 25 short-cycle at low temperatures?

It can. Your Silver 25’s minimum is 4.3 kW. Your radiators deliver about 4.2 kW at 55/45 and 3.3 kW at 50/40. Below ~60/45, emitter power may fall under the boiler’s minimum. The burner then cycles while the room stat still calls for heat. Plan around that limit when choosing flow temperature. [Elektroda, BUCKS, post #18376593]

How much heat do my Kermi panel radiators deliver at common temps?

Approximate totals: 6.0 kW at 70/50, 4.6 kW at 60/45, 4.2 kW at 55/45, 3.3 kW at 50/40, and 2.1 kW at 40/35. These figures exclude the bathroom ladder. Use them to compare against the boiler’s minimum output. Match flow temperature so radiator power meets or exceeds the minimum. [Elektroda, BUCKS, post #18376593]

Does the Salus 091flrf modulate the boiler or just switch it?

It acts as a room thermostat. It measures the room and enables or disables the boiler. Thermostatic radiator heads, if fitted, fine-tune other rooms. Place the Salus in a representative space, like a hall, for balanced control. Weather-compensated control is a separate option. [Elektroda, Wojewoda82, post #18355241]

What heat demand should I plan for a 48 mb2 older flat?

Using 100 W/mb2 as a rule-of-thumb, peak demand is about 4.8 kW at −20b0C. Seasonal average is around 2.4 kW. This is below the Silver 25’s 4.3 kW minimum, so expect cycling in mild weather. Size radiators and set flow accordingly. [Elektroda, BUCKS, post #18372141]

Can I reduce cycling by increasing pump speed/flow?

Yes, higher flow slows boiler temperature rise. That can prevent premature burner shutdown while the room still calls for heat. "I would increase the intensity of the medium flow through the boiler." After testing, fine-tune room temperatures by adjusting radiator lockshields. [Elektroda, gimak, post #18354143]

Should my pump run constantly when I lower flow temperature?

If you lower flow so radiator power falls below the boiler’s minimum, the burner will clock. The pump will then run non-stop, increasing electricity use. Comfort may feel better, but this behavior is a downside of that setting. [Elektroda, TomekO1976, post #18354720]

Are panel radiators better than cast iron for gas boilers?

Yes. Panel or aluminum radiators have low water content and less thermal inertia. They heat and cool quickly, reducing overshoot with cycling gas boilers. Cast iron radiators stay hot longer after shutoff and can overheat rooms. [Elektroda, Wojewoda82, post #18354081]

How do I balance radiators without thermostatic heads?

Use lockshields to throttle flow and smooth heat. 1. Fully open all valves and warm the system. 2. Close lockshields incrementally on rooms that overheat first. 3. Recheck comfort; adjust in small turns over several cycles. This slows radiator heat-up and reduces overshoot when the boiler cycles off. [Elektroda, Wojewoda82, post #18354081]

What happens in frost or very cold weather?

A 45b0C flow may not hold setpoint in frost. Increase the flow temperature to 50–55b0C during −10b0C conditions. Lower it again when weather improves to regain condensation benefits and longer cycles. [Elektroda, Wojewoda82, post #18354081]

Can weather compensation help this system?

Weather control helps most when minimum boiler power is low and radiators are ample. With about 3 kW minimum, 40b0C flow can run 24/7 around 5b0C outdoors. Silver 25 has higher minimum, so benefits may be limited. [Elektroda, Wojewoda82, post #18355241]

What radiators are in the example installation?

Kermi panel radiators: hall 600d7400d7100 mm, kitchen 600d7500d7100 mm, two per room 400d71400d7100 mm, plus a 700d7200d7100 mm bathroom ladder (14 rungs). These sizes underpin the output estimates. [Elektroda, Cypu87, post #18376167]

How do burner lockouts affect comfort planning?

Some boilers enforce a burner lockout after reaching higher temperatures. One user reported about 30 minutes at ~58b0C. Expect a short comfort rise from hot radiators, then a pause. Choose flow temperature to avoid frequent lockouts and maintain steadier warmth. [Elektroda, BUCKS, post #18376593]