ᐅ Design of Underfloor Heating for a KfW 55 Energy-Efficient House with a Ventilation System
Created on: 17 Feb 2023 16:29
D
dream2023
Dear users,
I am a bit overwhelmed with whether our underfloor heating is being planned correctly. The house is still in the shell stage. I have requested the installation plans and heat load calculations from the general contractor. The heat load was calculated according to DIN EN 12831. I have this calculation and the results from the planning office.
The pipe spacing is mostly 18cm (7 inches), except in the bathrooms (once 6cm (2.5 inches), once 12cm (5 inches)) and the utility room (24cm (9.5 inches)). What unsettles me more is the fact that in both bathrooms an undercoverage of the heat load is stated ("missing heat ...kW"). Additional heating devices are not planned there so far.
May I post the planning documents if I redact personal information and the data of the planning office?
Best regards
I am a bit overwhelmed with whether our underfloor heating is being planned correctly. The house is still in the shell stage. I have requested the installation plans and heat load calculations from the general contractor. The heat load was calculated according to DIN EN 12831. I have this calculation and the results from the planning office.
The pipe spacing is mostly 18cm (7 inches), except in the bathrooms (once 6cm (2.5 inches), once 12cm (5 inches)) and the utility room (24cm (9.5 inches)). What unsettles me more is the fact that in both bathrooms an undercoverage of the heat load is stated ("missing heat ...kW"). Additional heating devices are not planned there so far.
May I post the planning documents if I redact personal information and the data of the planning office?
Best regards
hanse987 schrieb:
If I understand correctly, a supply temperature of 35 degrees is being used. That’s a bit high for me. I would have calculated with a supply temperature of 30 degrees instead. We are building with a general contractor, and you’re basically fighting a losing battle. I tried something similar, but it has always been done that way; the system is well known, and builders don’t like what they’re not familiar with...
In our case, a supply temperature of 35 degrees was also calculated. We have 20cm (8 inches) spacing in the kitchen, and I discussed this with an expert. Of course, he understands my point but also clearly says that the general contractor doesn’t owe me anything else. I wouldn’t choose to build with a general contractor today, but two years ago the fixed price was decisive, and it still stands.
I would try to have another conversation about the overall topic.
D
dream202320 Feb 2023 15:06Wow, I already see and am gathering your thoughts.
Possibly lower supply temperature,
22°C (72°F) room temperature and 24°C (75°F) bathroom temperature.
I just noticed that the same manufacturer also offers studded insulation boards with different installation spacings.
Here, I have to say that I know he isn’t obligated to do anything. But it must be possible to find compromises. Of course, we would pay for anything beyond the standard scope if the additional effort is reasonable.
Possibly lower supply temperature,
22°C (72°F) room temperature and 24°C (75°F) bathroom temperature.
I just noticed that the same manufacturer also offers studded insulation boards with different installation spacings.
HnghusBY schrieb:
We are building with a general contractor (GC), and you’re basically fighting a losing battle. I tried something similar, but it has always been done that way; the system is well-known, and what the builder doesn’t know...
We were also calculating with 35°C (95°F); we have 20cm (8 inches) installation spacing in the kitchen, and I reviewed this with an expert. He understands me, of course, but clearly stated that the GC isn’t obligated to do anything else for me. Today, I wouldn’t build with a GC anymore, but two years ago the fixed price was crucial, and it still stands.
I would try to have another conversation about the general topic.
Here, I have to say that I know he isn’t obligated to do anything. But it must be possible to find compromises. Of course, we would pay for anything beyond the standard scope if the additional effort is reasonable.
K
KarstenausNRW20 Feb 2023 15:17dream2023 schrieb:
Here I have to say that I know he is not obligated to do this for me. But it should be possible to find compromises here. Of course, we would also pay for anything that goes beyond the standard if the additional effort is reasonable. Yes. Unfortunately, these are the issues that only come up during construction when building with a general contractor/developer. He is only required to provide a standard hydronic underfloor heating system.
Both the design with the spacing and the supply temperature align well with the fact that he is offering you the option that is best for him (= cheapest). In new construction, the design temperature should not exceed 30°C (86°F) nowadays. However, that means more pipes, a more complex heating circuit distributor, more time, etc.
This naturally makes the offer more expensive, and in competitive bidding—especially now with increased construction costs—the final price usually matters most.
I would be happy for you if you manage to get an adjustment. It is an investment in the future as well.
dream2023 schrieb:
I have to say that I understand he doesn’t owe me anything. But it should be possible to find some compromises here. Of course, we would also pay for anything beyond the standard if the additional effort is reasonable.In our case, it was always justified by referring to the "DIN" standard, but if the heating installer at least agreed to something like a 30-degree Celsius (86°F) supply temperature without extra costs, that would be great – which was not the case for us. I’m keeping my fingers crossed for you!Similar topics