ᐅ Comparison of Geothermal Heat Pump and Air-to-Water Heat Pump

Starting point: In the builder’s cost estimate, an air-to-water heat pump Nibe F2040 with a 180-liter (48-gallon) hot water tank is listed. Additionally, there are electric towel radiators and appropriate insulation to meet KfW-40 house standards. This package is supposed to cost us €13,900.

After some research, I found out that ground source heat pumps have a higher annual performance factor. According to the builder’s catalog, the air-to-water heat pump has a COP of 3.6, while the ground source heat pump has at least 4.5. In this case, it is a Nibe 1255.

Even though I don’t yet know the potential price for the 1255 from the builder, I would like to ask,

• what you paid for any borehole drilling for the ground loops?
• how the running costs compare between air-to-water and ground source heat pumps
• what you had to pay for your eligible Nibe units

I look forward to your answers, as a non-expert I feel a bit lost here (at least I do right now)...

The price-performance ratio of an air-to-water heat pump with an annual performance factor (SPF) of 4.5 or higher is unbeatable thanks to BAFA subsidies.
Those who carry out ground-source drilling for a KfW40 house might as well install a 500 kW (670 hp) engine in their lawn mower and use a moving truck for their twice-a-week supermarket trips, which could easily be done with a bicycle and two reusable bags.

Funny comparison. A lawnmower? Don’t people have tractors at home anymore? Driving to the discount store? Let them come.

To the point: financially, the air-to-water heat pump is ahead. Definitely pay attention not only to the technology but also to the entire system and its design. There are countless houses with great technology where staying inside is simply unpleasant. Some tech enthusiasts reduce this to a few measurements and judge their comfort by hygro- and thermometers. If you’re someone who trusts your own feelings, include this sense in your decision-making process.

Thank you for your responses!

Regarding the 500kW lawn mower: I understand that the initial costs of a ground source heat pump might be higher. How can I achieve an annual performance factor (Seasonal Coefficient of Performance) of ≥4.5 with an air-to-water heat pump when the catalog states 3.6?

Regarding comfort: My main focus right now is on finding the "best" overall package. Ideally, the ongoing electricity and operating costs should be as low as possible.

Operating costs are lower with a brine-water heat pump. Replacement in case of a defect is also likely to be cheaper. The heat source is expensive, but you can apply for a subsidy and you won’t have an outdoor unit, as an air-water heat pump as a split system was planned from the start.

Costs for probes are extremely individual. You won’t really have a choice anyway—you either accept the additional cost or you don’t.

There are a few air-to-water heat pumps that achieve an annual performance factor of 4.5.

For example, we will install the CHA-07 from Wolf. This allows us to reach an annual performance factor of 4.6.