Hello.
Fafunio13 wrote: So what should be the optimal water temperature for underfloor heating throughout the house?
Such that the heating works almost constantly and does not clock (I warm up the house quickly, turn it off and wait for the temperature to drop a bit, and again and again and again and again). Then it is the most economical.
I will not give a specific temperature, because the most appropriate one is different for different buildings. You have to find it yourself, achieving the effect described above.
Fafunio13 wrote: Do different boiler manufacturers have an influence on such a difference in combustion?
No. Condensing boilers, regardless of their manufacturers, have similar efficiencies.
There are also condensing boilers, which are in fact turbo boilers with a condensing attachment (the so-called recuperator). These have lower efficiency.
Your boiler is not one of them.
How do you have a regulated temperature on the floor heating. It goes directly from the boiler, is there any mixing system, etc.
Is this gas consumption from the beginning or for some time.
When was the boiler last cleaned and adjusted, maybe that's where the problem lies.
And one more thing:
Fafunio13 wrote: ... because I pay the gas bills 600-700 PLN monthly. A friend pays 250-300 PLN for a similar house.
Similar does not mean the same. Moreover, the size itself is not all. You also have to compare the thermal insulation method, building thermals, DHW consumption, etc.
For example: a very well insulated building can use much less fuel for CO needs than a poorly insulated building with a much smaller area.
Another thing is DHW. Heating a DHW consumes a huge amount of energy. Large differences in DHW consumption can generate large differences in gas consumption, even such.
Greetings.
