ᐅ New Gas Heating System for a New Build – Is Solar Thermal Needed for Domestic Hot Water?

Nordlys schrieb:
They know that the energy calculation must be submitted with the building permit / planning permission application. They also have a rough idea: if the house is like this and that, the heating system must be like this and that, otherwise it won’t work.

Then solar thermal is obligatorily added to the gas heating, even though a more innovative specialist could manage without it. (At least that was the case before the last energy-saving regulation update; I’m not fully up to date, but in borderline cases it may be worthwhile to have an expert run the calculations instead of letting the general contractor rely on “we’ve always done it this way” estimates.)

chaqrou schrieb:
I specified gas condensing boiler, underfloor heating throughout the entire house. As the manufacturer of the gas system, I favor Viessmann or Junkers. Still, the performance and equipment of the system are not described in the offer.

I would also specify the flow temperature, since it determines the cost-relevant pipe spacing (preferably as low as possible).

Unfortunately, as a layperson, I am unable to estimate the flow temperature or the installation spacing. Nothing about this is described in the scope of work.

Wikipedia: For use with heat pumps and/or solar heating support, surface heating systems are suitable because they only require supply temperatures of about 30-35°C (86-95°F).

Just ask the general contractor what they have planned. Alternatively, consult an energy advisor.

You don’t specify the pipe spacing. You simply say, “Build me a heating system (underfloor heating) that operates with a maximum supply temperature of XX°C (e.g., 30°C / 86°F).”

This way, you avoid getting a “low-temperature system” with a supply temperature of 55°C (131°F), which would never allow the use of a heat pump.

* At design conditions (depending on the region).

Hello,

chaqrou schrieb:
Unfortunately, as a layperson, I cannot assess the flow temperature or the pipe spacing. The construction specifications do not mention anything about this.

As a rough guideline, you can assume a pipe spacing of 15 cm (6 inches) in standard living areas and 10 cm (4 inches) in bathrooms.

If the spacing in living areas is even closer, you might quickly run into issues with the maximum length of the heating circuits. This then means having multiple heating circuits in each room, which of course significantly increases the costs!

Best regards,

Andreas

My opinion: I wouldn’t invest more than technically necessary here. What matters is a well-insulated, airtight building envelope without significant heat loss. All of them build that. Then, the savings from a low-temperature heating system compared to a standard one will be so minimal—in terms of actual money—that the extra effort isn’t worth it. Use a boiler system with about 5 or 6 square meters (54 or 65 square feet) of solar panels on the roof for hot water, partly because it’s politically favored, and that’s it. I’d rather spend your money on a nice garden. Karsten

Nordlys schrieb:
Junkers/Viessmann, 5 or 6 sqm (54 or 65 sq ft) solar panels on the roof for hot water and because the government supports it, done

So far, solar thermal systems are not planned, and the calculations have not yet been done. The general contractor wants to handle this when applying for the building permit / planning permission. If it’s not necessary, I would prefer to invest the money elsewhere.