ᐅ Is a buffer tank useful for a heat pump?

Exactly the same points are on my mind:

- Ask neighbors and compare what is different
- Perform hydraulic / thermal balancing

Definitely avoid a combination storage tank; another forum is full of unhappy owners of combination storage tanks...

Daniel-Sp schrieb:

Definitely avoid a combination storage tank; another forum is full of unhappy owners of combination tanks...

Because of the small domestic hot water tank of 165 liters (44 gallons), I am leaning towards a storage tank with an internal domestic hot water coil.

Ideally, an issue (such as a dirt trap in the heating circuit/brine circuit, temperature sensor, pressure relief valve, etc.) would be found that causes the frequent starts and stops, which can be fixed so that I don't need a buffer tank to solve the problem.

There is nothing against using a larger hot water storage tank, with or without a fresh water station. A stratified tank or combination tank is not necessary for this. These are sometimes also installed as a hydraulic separator.

Daniel-Sp schrieb:

There is nothing against using a larger hot water storage tank with or without a fresh water station. This does not require a stratified tank/combination tank. These are also installed as a hydraulic separator.

We were recommended a buffer tank for the heating system to prevent frequent cycling. If I only expand the hot water storage tank now, I would be ignoring this recommendation.

My thought was to use a combination tank because
- frequent cycling can also occur during hot water generation,
- the 165-liter (43.6-gallon) hot water tank is quite small for five people.

Or do you think one should have both a buffer tank AND (separately) an expansion of the hot water storage tank?

jx7 schrieb:

- the hot water storage tank with 165 liters for 5 people is indeed very small.

I wonder how you managed with that in the past. When I shower extensively with my three children (which takes time with three girls having long hair), our 300 l (79 gallons) tank is almost empty or has dropped to 25°C (77°F).

I just finished reading the entire thread. Basically, the only remaining solution for a poorly planned heating system is a properly sized buffer tank for the heating. With a 3 kW lower modulation limit for the well-insulated house, the heat pump can’t help but cycle heavily, leading to premature aging (keyword: compressor starts).

I would actually use two separate tanks and, as soon as the heat pump needs to be replaced, switch to a significantly smaller unit and disconnect the heat pump buffer again.