ᐅ Hybrid heat pump for new single-family home construction

Created on: 13 Oct 2013 17:49
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Flobi
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Flobi
13 Oct 2013 17:49
Hello everyone,

We are about to build a single-family house with approximately 140 m² (1500 sq ft) of living space and are currently considering the most suitable heating system. We have already looked around in this forum as well. Until yesterday, we planned to install a gas condensing boiler combined with a solar system for domestic hot water and heating support. However, yesterday we visited a trade fair and found an interesting alternative.

It is a hybrid heat pump, meaning a combination of an air-to-water heat pump with a gas condensing boiler. After extensive online research, we decided against a classic air-to-water heat pump because at low outdoor temperatures it has to activate an electric heating element to prevent freezing. This makes the system less efficient than initially assumed. The hybrid heat pump uses as much environmental heat as possible and only as much gas as necessary. A sensor decides, based on outdoor temperature, required flow temperature, and gas and electricity prices, when the gas condensing boiler should be switched on to cover peak loads. The heat pump does the main work. Once it is no longer operating efficiently, the gas condensing boiler takes over, which helps keep electricity consumption low.

To me, this system currently seems like the ideal solution for us. Now I am wondering why these systems are so rarely promoted and offered. They represent a good combination of the proven gas heating system and the environmentally friendly heat pump. The initial costs are manageable and, according to some other online sources, are amortized after about eight years.

My question is whether anyone has already installed such a system, has heard different experiences, or can share a personal opinion. Tomorrow, we will also contact the specialists we trust to discuss this further.

Best regards!
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fkay01
14 Oct 2013 03:18
Hello, I’m curious about how much a system like this typically costs? I haven’t decided yet either. A air-to-water heat pump was planned so far, but I’m not sure if it’s really effective enough at below-freezing temperatures. We are planning a freestanding wood stove for the ground floor, but only underfloor heating for the upper floor. Best regards
€uro
14 Oct 2013 07:24
Hello,
Flobi schrieb:
.... After extensive online research, we decided against a conventional air-to-water heat pump because it has to activate an electric heating element at low outside temperatures to avoid freezing....This makes it seem less efficient than initially assumed.
When researching online, one should always be cautious before drawing conclusions for their own construction project! Unfortunately, quite a few air heat pump systems are inadequately designed. Well-designed systems achieve a seasonal performance factor (SPF) greater than 3.5. The share of the electric heating element is less than 1% of the annual heating load (heating mode) and up to 0.5% for domestic hot water. So it is hardly significant.
Flobi schrieb:
.... As soon as it no longer operates efficiently, the gas condensing boiler takes over, keeping electricity consumption low.
For what percentage of operation do the considerable costs for the additional gas connection justify themselves?
Flobi schrieb:
.... For me, this system seems to be the ideal solution at the moment..
Sometimes appearances can be deceiving
Flobi schrieb:
.... Now I wonder why these systems are advertised and offered so little.
Because they are uneconomical!
Flobi schrieb:
.... The acquisition costs are manageable and, according to some other online information, amortized after about eight years...
I would like to see that for myself

Best regards
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Flobi
14 Oct 2013 18:38
We are also planning to have a fireplace in the living room. For a short time, we considered a water-based fireplace to use the heat for supporting the heating system. However, this would have required an even larger storage tank for the heating system.

@€uro: I have already read your comments in other posts here on this forum. By now, I know that you are convinced of a well-calculated and properly installed heat pump. We are simply not convinced, and I doubt this lack of confidence is due to incorrect calculations. My husband works in customer service and has discussed this topic with many acquaintances and colleagues, including those from other companies. A solely air-to-water heat pump is not our choice. We would install a gas connection anyway, so we have these costs regardless.

We would continue to appreciate comments regarding the described hybrid system.

Best regards!
€uro
14 Oct 2013 19:13
Flobi schrieb:
...@€uro: I have already read your comments in other posts here in this forum. By now, I understand that you are convinced of a well calculated and properly installed heat pump....

It is just one of several options, which unfortunately has gained a somewhat bad reputation due to poor execution. Therefore, I gladly take on the role of defending it, although I have probably planned more ground-source heat pump systems than air-source ones.
Flobi schrieb:
....We would install a gas connection in any case, so the costs are inevitable.
In that case, a fully modulating gas condensing boiler could indeed be a suitable choice. I’m not trying to persuade anyone, as I am completely technology-neutral. By the way, there are also gas-powered heat pumps!
From my experience, hybrid or combined solutions often live up to their name: a compromise.
I let myself be convinced primarily by numbers. Here, that means: first, results from a detailed analysis of actual demand (capacity, energy) for heating and hot water are needed to evaluate any investment!

Good luck!

Best regards
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ErikErdgas
16 Oct 2013 09:43
Hello Flobi,

I think that combining a hybrid system with an additional heating system, in your case a fireplace, goes a bit too far. Therefore, I believe you would be better off not integrating the fireplace into the heating system as well. Regarding the gas heat pump, there are now several user reports available on various information sites, as well as specific subsidy programs from BAFA. Besides the manufacturer you mentioned, several other manufacturers already offer gas heat pumps, so there are brand-independent options for comparison as well.

Best regards, Erik