Interpretation of Gas Condensing Boiler - Practical Experience!

Hello everyone,

I have been reading about the topic of heating and design over the past few days and keep encountering different approaches. I would like to hear from those who have installed a gas condensing boiler with underfloor heating in their new build about how it was designed.

The following points would be of interest to me:

Flow temperature:

Pipe spacing:

Bathroom and window side individually or closer spaced (Yes / No):

Maximum length of the heating circuits:

Material of the pipes (PEX / aluminum composite):

For how many sqm was one heating circuit designed? Ideally, the sqm of the rooms and number of heating circuits.

Brief feedback from practice:

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I currently have offers that assume flow temperatures of 45 degrees, pipe spacing of 15 cm, and no individual adjustments for bathroom and window, using aluminum composite pipes instead. The heating circuits are supposed to have a maximum length of 80 meters. This seems rather suboptimal compared to my internet research.

With a corresponding number of responses, at least a trend could emerge.

Many thanks in advance.

I will get in touch tomorrow. I need to pull the data from the folder, I don't have it memorized.

Have a heating load calculation done with a laying recommendation for the underfloor heating - then you have everything correctly presented.

In addition, there are factors that cannot be done arbitrarily: the maximum length per heating circuit is 100m - and even with very tight laying radii in the bathroom, the area alone will not be enough to reach the usually desired 23-24 degrees if all other rooms are designed significantly lower.

I also find 45 degrees flow temperature quite high - why not design for 35 degrees?

Who does the calculation?

Engineering offices - or just google it, there are quite a few providers. It cost me around 200 euros.

I have 35 degrees...15cm everywhere at the floor-to-ceiling windows 5cm max length is just under 100m and was always enough for about 15sqm...Feedback from practice it works quite well without RTR the 24 degrees in the bathroom are no problem otherwise everywhere 21-23