ᐅ Which air-to-water heat pump is best for a new build?

Hello everyone,

We are planning to build a single-family house without a basement (ground floor + upper floor) of about 170 sqm (1,830 sq ft) and are looking for a good air-to-water heat pump for it. The unit should be inverter-controlled and a monobloc system for outdoor installation. It should be as efficient as possible, but at the same time as quiet as possible.

Our builder usually installs heat pumps from Alpha Innotec. Either the LWDV or LWAV+ model would fit the above criteria.

What do you think of Alpha Innotec and these two models? Does anyone have experience with them?

I would also appreciate recommendations for other systems and manufacturers.

Best regards,
Felix

From my own experience, I would recommend the Panasonic Aquarea as a great alternative. It is also more affordable. The question is whether your builder or their heating contractor is familiar with it.

P.S. I have installed two of the Panasonic units myself.

If the heat pumps have been on the market for less than 3 years and ideally still use R290 as the refrigerant, they are likely to be good.

More important than the brand is to ensure that the pump’s output does not exceed the heating load of the house. The heating load must be calculated and provided room by room (which is necessary anyway for designing the underfloor heating; if this is missing, the job will be done poorly). The pump should then not be larger than the combined heating load of all rooms, without adding extra allowances for domestic hot water, pets, or elderly occupants.

Additionally, you will want an exemption from the EER (energy efficiency ratio); this exemption is applied for by the planner who also carries out the calculations, and you do NOT want a heating buffer tank (not to be confused with the domestic hot water storage tank).

These are just the key points. You can find detailed explanations for all this in nearly every other heat pump thread here.

Deliverer schrieb:

If the pumps have been on the market for less than 3 years and ideally still use R290 as a refrigerant, they can’t be bad.
More important than the brand is to ensure that the pump’s capacity does not exceed the house’s heating load. The heating load must be calculated room by room and provided to you (this is necessary anyway for designing the underfloor heating; without it, it will be done poorly). The pump should then not be larger than the combined heating load of all rooms. Without adding allowances for domestic hot water, pets, or elderly occupants.
Also, you want an exemption from the EER (this is applied for by the planner who also does the calculations) and NO heating buffer tank (not to be confused with the domestic hot water storage tank).
These are just keywords for now. You can read about why this is the case in nearly every second heat pump thread here.

Thank you very much for your helpful reply. However, I have a few questions for clarification:

> The LWDV as an inverter-controlled air source heat pump has a power range from 3 to 9 kW.
At Alpha Innotec they say: "The devices are recommended for the following total building power demand: LWDV 91-1/3 = 6-11 kW." To my knowledge, the LWDV isn’t available in any other size/design. At the same time, my builder requires me to use Alpha Innotec. Could it still be possible, despite modulation, that the LWDV is oversized for our new build (single-family house with about 170 sqm (1830 sq ft) without basement)? Unfortunately, I don’t yet know the exact heating load.

> What exactly is the EER and why is an exemption needed? Does this have to do with subsidies? If so, we are building a new house. Currently, there are no subsidies available for that anyway.

Many thanks for your support!

I operate the LWDV for 200m² (2,150 sq ft) of living space with a heating load of 5-6 kW. If the underfloor heating is properly designed, a wall heating system is installed in the bathroom, the individual room controllers are deactivated, the bypass valve is closed, and a hydraulic balancing is carried out along with a low heating curve, the pump can be managed well and here it has an average running time of over 5 hours. In winter, the pump ran continuously for more than four weeks. However, the pump is still somewhat oversized. I originally chose it because of the >10k BAFA subsidy (only this manufacturer was eligible).

If you opt for the standard design and settings from the heating installer and do not want to handle this yourself, it is better to choose a weaker model. There is a risk that the pump will not dissipate its heat properly and will switch on and off constantly.

Hunter2605 schrieb:

Unfortunately, I don’t know the exact heating load yet.

Before that, neither you nor the heating installer should worry about the model. It can basically only go wrong. Determine the heating load first, then choose the appropriate model. Not bigger, even if it modulates aggressively.

A 9 kW heat pump is definitely far too large for a new build. That’s the output my uninsulated older house of 260 m² (2800 ft²) requires. For your case, I estimate around 3.5–4 kW. And unlike oil or gas systems, an oversized heat pump is really bad. It’s much less efficient and breaks down much earlier than necessary. It also requires costly additional components like buffers, three-way valves, and differential pressure valves, which you could avoid by selecting the right-sized heat pump. Oh, and of course, a 4 kW heat pump is much cheaper than a 9 kW one. So this sizing actually means a difference of several thousand euros.

Hunter2605 schrieb:

> what is EER about and why is an exemption needed?

I’m not exactly sure where they are mandatory. I have equipped both a new build in 2016 and an older house in 2020 without them. But apparently, they are required somewhere. The people who calculate the heating load can also apply for the exemption.

In any case, you should definitely avoid them. They cost a lot of money. The electrician has to lay many more cables, then they consume electricity continuously, and they also mess up the precise control of the underfloor heating—all this without any actual added benefit. So inform yourself and get rid of them; this is technology from 40 years ago, before heat pumps existed.