ᐅ Ground-source heat pump with buffer tank and underfloor heating

Created on: 31 Dec 2020 18:55
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WilderSueden
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WilderSueden
31 Dec 2020 18:55
I have now received a construction specification for the offer from the local general contractor and am not entirely sure what to make of the heating system:

Execution with a geothermal heat pump. Installation of a Viessmann heat pump or equivalent. Capacity based on heat load calculation. Deep drilling according to the calculation by a specialist office. Supply and installation of a 390-liter (103-gallon) hot water tank and a 400-liter (106-gallon) buffer tank.

Execution with thermal insulation according to heating system regulations. The heating pipes will be installed within the screed insulation, visible in the boiler room. In the living areas on the ground and upper floors, a underfloor heating system with individual room controls will be installed.


At first, I find the hot water tank rather large for three people, but that's okay; it can probably be sized smaller if that makes a financially significant difference. The bigger question for me is the buffer tank and whether it is needed at all. I did a bit of research, but the articles I found online usually refer to air-to-water heat pumps. Overall, a buffer tank is generally considered unnecessary for underfloor heating, and unlike air-to-water heat pumps, the ground-source heat pump doesn’t have the issue of becoming less efficient once the sun goes down in winter. Is there any good reason to install a buffer tank with geothermal heating?
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Daniel-Sp
31 Dec 2020 19:24
WilderSueden schrieb:

Is there any good reason to install a buffer tank with geothermal heating?
Yes, exactly one. To maximize the HVAC installer's profit.
A 390-liter (103-gallon) domestic hot water tank for 3 people is clearly oversized.
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nordanney
31 Dec 2020 20:59
Buffer tank: unnecessary
390l (103 gallons) hot water storage: depends. A simple storage tank with a small heat exchanger is fine. As a high-performance storage tank – unnecessary
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WilderSueden
1 Jan 2021 15:15
Maximizing profit by the hired heating installer is definitely not a good reason for me 😉
I'll add that to the list for the next discussion
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dhd82
2 Jan 2021 08:09
Hello,

we also have a brine-to-water heat pump, but without a buffer tank. It is not necessary.
The volume of the tank seems too large for 3 people; we have 300 liters (79 gallons) and there are five of us.
I would avoid phrases like “or equivalent” in my scope of work description; the exact product to be installed in the house should be specified. You could ask which alternatives to Viessmann are available and then choose the heating system you prefer the most.