Economical Gas Boiler Heating: High vs. Low Radiator Supply Temperature Settings (CO)

Hello.
There was already such a thread here, but it remained without a specific answer, so now I'm trying to ask a question.
What is the more economical way for a gas boiler in the case of CO?

Should the supply temperature to the radiators be set higher on the stove (e.g. 75degC) or better if it is lower.

We then have two situations:
1. The boiler turns on for a shorter time, but with higher burner power to heat up to a higher temperature.
2. The boiler turns on for a longer time, but with a lower burner power, keeping the temperature on the stove lower.

Which of the two cases should be more economical?

The most comfortable situation is when the boiler provides only as much heat energy as is radiated by the building.

If it is a condensing boiler, there are greater savings at a lower temperature. In the case of other boilers, the temperature should probably be set at such a level that the radiators and the rest of the installation heat sufficiently with a slight margin. Higher temperature, higher losses on e.g. pipes are known, and I think that the burner will be too, because more heat escapes to the chimney.

on117 wrote:

If it is a condensing boiler, there are greater savings at a lower temperature. In the case of other boilers, the temperature should probably be set at such a level that the radiators and the rest of the installation heat sufficiently with a slight margin. Higher temperature, higher losses on e.g. pipes are known, and I think that the burner will be too, because more heat escapes to the chimney.

The problem of too high flue gas temperature in boilers with a closed combustion chamber is practically minimal if the flue gas outlet passes through the suction duct, returning heat to the sucked combustion air, increasing the combustion temperature with the same gas consumption.
I used to do practical tests and at a temperature of 70 degrees in the boiler the flue gases are about 140-160 degrees C, but after going through 80 cm. the suction pipe was about 25-35 ° C (winter season) and after these tests I immediately installed the boiler with a closed chamber and the "turbo" system.
Gas consumption decreased by 30%, and the apartment was warmer than before, because I did not have to heat the air that the old boiler took from the apartment.

What you write is right. What I mean is that the manufacturers of condensing boilers recommend a lower water temperature, e.g. about 60 degrees, because then there are greater gas savings. Why this is so is either explained or you should ask the manufacturer. There are no recommendations for other boilers.

I'll throw in my three cents. My VZS boiler, 4.7kW-24kW, controlled by SuperCAR with an external probe, sets the heating temperature by itself. Comfort lies in the fact that the room temperature fluctuates by +/- 0.2 C, so it is imperceptible. And the savings compared to the old boiler are approx. 30%.

It is the producers who should provide more precise parameters of the boilers so that customers do not have to make their own combinations, because, to be honest, each type of boiler has different operational requirements, but which will be the most economical, they avoid it.
I used to work in a thermo-energetic plant, and there, water (not steam) boilers required 120-130 degrees Celsius and 9-12 atmospheres to work economically and mixing at the output up to 90 degrees per city. But this is a completely different system and scale, because the order of 50GJ from one boiler.
The greater the temperature difference, the more heat is transferred between the carriers, but too much difference can damage the boiler, so economic operation is somewhere in the middle. The only recovery that can be achieved is the heat of the flue gases outside the boiler.

https://www.elektroda.pl/rtvforum/topic1516964.html

I can add to the topic that it is a gas combi boiler with an open combustion chamber and standard double-panel heaters.

From what I have read in several different places, the following conclusion can be drawn.

The operation of the boiler is more economical when the boiler runs longer with a constant temperature than its frequent switching on and rapid heating and then switching off.

MarudaP wrote:

The most comfortable situation is when the boiler provides only as much heat energy as is radiated by the building.

Maruda P. Regarding comfort, your opinion is obvious, otherwise it will get colder or warmer in the building. However, it does not completely answer the question of how to use the boiler (and the radiators) more economically.

onyx8 from your link I chose an excerpt. You wrote:

Quote:

Design and reality. Of course, the reality verified everything and I started to look for what was wrong - a large number of burner starts, high gas consumption in the house, not too warm. which helped - limiting the furnace power to 60%

I understand you decreased the heating temperature on the stove, right?
This is now a topic of panel heaters. It is recommended that the temperature of their operation should not be lower than 60degC, otherwise their efficiency will decrease even by 50%. Combining all these factors so that the cost of operation is as low as possible is not easy.

I have a Vitodens 333 condensing furnace with a flow temperature of 50 degrees. I have aluminum radiators with a large area.

The electronics of my stove allow for smooth power regulation from 0 to 100%. It can be electronically limited so that the stove does not run at full power.

If these are ordinary heaters, they should work at 75 degrees, supply 55 return, and so have to be set because they have such characteristics.

Set the power supply to 75 degrees is simple - it is more fun to set the radiator orifice so that the water cools down to 55 degrees.

Then limit the furnace power to keep it running with the minimum number of burner starts.

I think Maruda meant continuous work, i.e. without long breaks.

When lowering the temperature, you can increase the flow in order not to significantly reduce the efficiency of the radiators, to some extent, of course.
If you want to experiment, set the temperature to e.g. 60 and heat for a week, checking the gas consumption.
After one week, lower the temperature on the furnace 50 and increase the speed of the pump by 1 step (gear).
The next week, set it to 70 and reduce the speed of the pump
After that, compare the results when there is the least wear. Of course the temperatures outside should be similar, it's best to write them down as well.

when designing installations, we try to avoid too high flows. Having not the best regulators, you can lead to high flows to quite annoying noises, especially in the bedroom, if you want to rest and here the radiator hisses, which spreads perfectly throughout the building,

onyx8 my stove has no power setting. It is Buderus FC 2520 S. It is possible to set the maximum temperature of the boiler circuit. At the moment I have just set it to 75degC. Two-panel heaters should probably be supplied with this temperature. The situation for me is a bit strange because the stove works at such a temperature when it has to heat up the room. As soon as it heats up, the temperature decreases and the furnace is kept at about 60degC. And this is probably the modulation of the furnace power in my case. Maybe the point is that the stove should not heat constantly at the set temperature, because it would force it to be turned on and off frequently. The furnace itself modulates the size of the flame by increasing or decreasing the temperature. It probably depends on the temperature difference in the room and the settings on the room regulator. The smaller the delta, the lower the temperature on the furnace.

J. Kleban testing in the short term is not easy because you will never find yourself in the same weather conditions. It is not only about temperature, but also about the strength of the wind. It's best to practice this for at least two seasons. This will allow you to get a bit more comparable results, although it also depends on what winter will hit.

As I have already written, I conclude that the more economical operation of the furnace is when it runs longer but with less power.

In connection with the above, I am still wondering if it is worth setting the automatic temperature reduction for the night (I omit the issue of comfort). In this case, the stove will have to suddenly heat the cottage in the morning, i.e. it will run "in waves" and not at a constant temperature.

I personally sleep better at a lower temperature and my bedtime setting is 17 degrees. Savings are big on night reduction, for example increasing the day temperature from 20 to 21 degrees increases gas consumption by 3%.
Reducing the power will result in greater inertia of the system - the stove will take longer to reach the set temperature and it will save the burner from a large number of starts and stops.

Added after 10 [minutes]:

in the case of standard furnaces, there is such an automatic system that prevents the furnace from cooling down - the standard 37 degrees is the dew condensation point. In simple terms, the temperature of the furnace should not be lower than this point and it is different for different furnaces. It prevents the furnace from rusting due to the so-called furnace sweating.

60 degrees in standby mode is too much. Generally, in order to efficiently transfer the gas combustion energy to the water and not to the flue gases in the chimney, this water must have a sufficiently low temperature. Of course, there is also a temperature limit at which the stove starts to sweat - this is also not good.

I have a condensing furnace so I can regulate it in a wide range and the condensate pours from it terribly - 15 liters a day to average.

The efficiency of my stove is so great that I can put my hand in the chimney right behind the burner without burning

Hello, I will put my three cents to the topic because I also heat it with natural gas and at the beginning you have to look at the invoice for gas and its components gas price 0.9350, subscription 6.00 per month, fixed network fee 6.0236 per month, variable network fee 0 , 4668 and, of course, 22 percent VAT, these are the prices, and for the last period of summer time, i.e. about 6 months, I took 86 meters of gas and paid PLN 277, it comes out that one meter costs about PLN 3.22 per meter and here is a jump to the cash register by PGKIN is a fact that in the winter the fixed and subscription fees will be spread more favorably because there will be more meters, but in summer it is a horror, and gas at CNG stations costs PLN 2.1 per meter and refueling without any subscription fees and other crap what's the point of keeping a connection for the cooker only, it's better to refuel the 100-meter cylinders and keep it calm for the whole summer, so that for owners of cookers only it's an alternative for a small amount of money

SP7SEC wrote:

it comes out that one meter costs about PLN 3.22 per meter and here is a jump to the cash register by PGKIN, the fact is that in the winter the fixed and subscription fees will be spread more favorably because there will be more meters, but in summer it is a macabre, and gas at the stations CNG costs 2.1 zlotys per meter and refueling without any grace without any subscription fees and other crap, what's the point of keeping a connection for the stove, better to refuel 100 meters cylinders

If you heat with natural gas, how much does it cost you cubic meters per year?

Other alternatives are a propane butane tank or fuel oil if there is space. Of course, you need to count the cost of the tank and installation, after how many years it will pay for itself. Which I doubt, unless it gets cheaper or they close the gas cap again as it was a year ago. Additionally, in the case of heating oil, the nozzle in the furnace must be replaced. Then prices are counted per liter, I don't know how many cubic meters it is. The value of fuel oil is greater, then less liters will burn

For the entire year of gas operation (stove, hot water and heating, temperature 20C / 17C), I used 2300 m> 3, cost PLN 5,100, which is PLN 2.20 per cubic meter.

Hello,

I am here for the first time. Perhaps the topic has already been touched upon.
I have an apartment of 75 m2 (including a basement connected by stairs), insulated with polystyrene, open on 3 sides. The stove is Immergas Avio 24 kW, condensing with an open chamber and a room thermostat. How to optimally set up a stove so that gas bills are reasonable. Will lowering the temperature during the night and during your absence reduce gas consumption? The CO indicator has 9 divisions, in my case it is set to 6 (I do not know if it is not too few), the DHW indicator is also 9 divisions, I set it to 3, thermostatic valves on radiators to full in all rooms except the basement (2 radiators there at half power) . Yesterday I did a test, with these settings for 21 hours, including the night, the thermostat was 20 degrees C of constant temperature and it consumed 7 m3 of gas, including washing and cooking. Is not it too much? So daily it gives 8 m3 - 240 m3 per month (240 * 1.51 + 68 subscription = PLN 430 per month). Honestly, 20 degrees is a bit too cold. Should I increase the temperature on the stove and thermostat and lower it at night and when I am at work? I am asking for advice.

Ralfi6

everything is correct, only one irritates me that 10 years ago when they gasified the town, I had to spend about 2,000 for the construction of the gas pipeline and now PGNIGE is charging tribute for its exploitation and how much net 17.70 per month is probably a slight exaggeration of 259.20 gross a year for nothing regardless of gas consumption, now multiply by the number of recipients it is called a monopoly, the cash for bonuses is ,,,, is also on the fun for the president and you, little bastard, pay and do not complain

SP7SEC do not mix. The topic is specific - Fr. economic operation of the boiler

Ralfi6 your 9-step divisions may correspond to another "tens of degrees" on the furnace. So 6 is probably going to be 60degC. Too much, too little - I also want to find out in this thread.

There are quite a lot of factors influencing the operation of the furnace. Indoor and outdoor temperature, wind, fireplace, day / night temperature difference setting, hot water consumption, etc., etc. I try to control it myself. I started monitoring my gas consumption on a daily basis, depending on the parameters above. Having a certain base of values, I will compare myself what settings on the stove will be, at least in my case, the most favorable.

I still encourage you to answer the question posed at the beginning of this thread.

My two pennies - I warmed the house in the summer and hesitated for a long time with the ceiling insulation (Gierek's block), but I decided and covered the flat with a layer of hard polystyrene for the floors 5 cm and a new roof. From what can be observed, the greatest savings in heating were the ceiling insulation, which gave me gas savings compared to last year (2000) for the same period PLN 900 for two months (including cooking and hot water) a bill of PLN 1100 for two months 110m2 of space to be heated. Cast iron radiators on the stove (17 years old) temperature about 70C. All the savings, whether it is after the heating season, but for now, knock on b / good. My temperature is a bit too high, 23 C, but I have a person who is not fully fit and who has problems with circulation. too hot and her too cold.
In the future, I will change the furnace to a closed combustion chamber, which should save about 30% and insulate the ceiling from the basement and the foundation.
Kuzyn has a wooden house insulated with mineral wool on a pillow - insulation insulated foundation monthly cost of gas and electricity consumption does not exceed PLN 500. But for the second time in my life I am not going to build myself and I have to be happy with what I have hi hi.
Greetings to colleagues and I wish you big savings in heat, hi outside the window, currently -16 frost.
73!

Ralfi6 wrote:

... thermostatic radiator valves on full power in all rooms except the basement (2 radiators there for half power).

Set the temperature for each room on the thermostatic heads. Only in the room with the regulator, leave it on full. There are big savings here too. In your settings, each radiator receives heat as much as you give it, instead of as much as needed.

Hello everyone, I wanted to share my observations and I am very interested in the answer to the question posed here.

I started the heating 10 days ago, so my observations are extremely short and knowledge is scarce. I have a Brotje WBS22C furnace and from the moment of starting the boiler water temperature was set to 75 degrees Celsius, the boiler did not turn off at all for 5 days, heating 24/7. I noticed that despite the exceeded temperature set on the room controller, it does not turn off, the room was 19.4 degrees Celsius, with the set temperature of 18. Only when I set the water temperature in the boiler to 55, it turned off. However, the next day it turned out that it heats the same only for the lower settings. From my observations it appears that he constantly heats the water so that it is 55 degrees. when it drops to 44.9 it turns on, at 55.1 it turns off, i.e. in practice it turns on and off several times within 10 seconds. I don't suppose this device is that primitive so I assume it's set up wrong. I fumbled a bit in the settings and I hope it will be a little better now, but I left the temperature in the boiler at 55 degrees. I am waiting for the end of this thread, because I do not know if I should go tomorrow to increase the temperature to 75 degrees.

greetings.

Zayer2 two things:
Did you turn on the stove 10 days ago? No wonder that the stove was running non-stop for several days because your walls, including the equipment (furniture), were cold. It all works like a battery and had to be "charged" with heat in the first place.

Changing the temperature setting on the stove will not help you. It looks like your stove starts at full power, heats the room and shuts off waiting for the temperature to drop. While rummaging around on heating, I came across ways to regulate the stove. There should be smooth temperature control by modulating the stove power (I mentioned it above when writing about my stove) In your case, it looks like the stove only works on the principle of on / off with full power in the range of 5degC. Perhaps it is a regulator malfunction or this type has it.

Referring to my question at the beginning of this thread, your stove is running short but often with temperature fluctuations. I'm still waiting for answers, and better for experiences, which is better.

_magu_ wrote:

[b] ...
Did you turn on the stove 10 days ago? No wonder that the stove was running non-stop for several days because your walls, including the equipment (furniture), were cold. It all works like a battery and had to be "charged" with heat in the first place.
....

This is a house under construction and of course I realize that the walls have to warm up so I let it pour gas for 5 days.

Today I changed something and in the evening I will go to check the results. It was definitely misplaced. The first symptom was that it was impossible to go below 18 degrees on the regulator and on the stove. Now you can, but only until the 15th, regardless of whether it is day or night. Nevertheless, it still seems to me that the stove turns on despite the temperature in the room higher than the set temperature. I also found data when setting up the burner, there are almost always 10 (you do not set it manually, it changes by itself), very rarely 0 and sometimes 99. Is it the burner power? Is 10 maybe some kind of work with super minimal parameters, like a candle that consumes the minimum amount of gas? Someone wrote that it is not good when the stove turns off and on constantly, maybe it is a protection against such an operation. Anyone know this furnace?

SP7SEC wrote:

everything is correct, only one irritates me that 10 years ago, when they gasified the town, I had to spend about 2,000 for the construction of the gas pipeline and now PGNIGE is charging tribute for its exploitation

Nothing has changed in this, or rather it is worse. For example, 10 meters of a simple installation from the connection (meter) to the furnace costs about 3,000. Maybe someone will say that it can be cheaper, I will believe it, but I know the price.

I was at the construction site yesterday, unlucky because the temperature outside had dropped a lot. It was below -11st. Anyway, I found the room temperature to 16.6 degrees. at the set point 15, the burner badge was on and that worries me. Why does the stove work even though the temperature is above the desired temperature? Is this what you wrote about, slow running of the stove so that no moisture would appear in it? How to check the power of the stove, because it actually works quieter than when it really heats up to the set temperature. One more change that I noticed after yesterday's adjustment is despite the set temperature in the boiler 55st. shows 40 degrees and you are in a hurry to heat it, but when I set the set temperature in the room to a higher than foreign one, it suddenly started to heat the water in the boiler to the set 55 degrees. So maybe everything works fine, only after ..... it consumes heavy gas if it is warmer than I set ??
Anyone have an idea?

I also did a small gas consumption test, in this mode, the first when it comes, but the temperature in the room is exceeded, it consumes 0.1 cubic meters. gas for 36 sec. But for me such tests are not very reliable.

there are several reasons for heating:
1.the furnace keeps the temperature higher than the condensation temperature of the water in the furnace - anti-corrosion protection - if it is not a condensing furnace it is around 38 degrees
2.protection against freezing of water in the installation - I set the temperature at which the outside temperature of the stove will heat the water, although there is no need for it - for me it is the default temperature -1 degree outside I changed it to -5 degrees
3. Incorrectly selected heating curve

it is condensate and it probably is as you write, but how to check it, how to check with what power it works in this "anti-corrosion" mode, and how much it works normally.

Zayer2 wrote:

From my observations it appears that he constantly heats the water so that it is 55 degrees. when it drops to 44.9 it turns on, at 55.1 it turns off, i.e. in practice it turns on and off several times within 10 seconds.

Zayer2 wrote:

Anyway, I found the temperature in the room to 16.6 degrees. at the set point 15, the burner badge was on and that worries me. Why does the stove work even though the temperature is above the desired temperature?

Do you have regulators, e.g. on radiators, or, if floor ones, it is possible to regulate the temperature in each room? Do you only have one stove controller in the living room? Do you have an external sensor?

If you have a regulator on the radiator, set it to a lower temperature, then the room will be as much as you want, and the stove will have 55 degrees. So generally it's 55st. it is minimal for a furnace.
The stove heats by so-called heating curves. e.g. it has information about the outside temperature from the sensor -11st. And it heats more, the warmer it will be less. It seems that it would suit you if you lived because you wrote that the temperature changes from 4 to 7 and maybe more. You have to ask if you can put it in such a mode that it maintains the temperature in the room, e.g. 15 degrees Celsius. or less.