ᐅ Is the additional cost of an air-to-water heat pump compared to gas justified?

Created on: 13 Feb 2022 14:20

Hello everyone,

I could use your advice on choosing a heating system. We (2 adults, 4 children) are currently in talks with a general contractor (GC) about a house, and so far it sounds pretty good. The scope of work is acceptable. We are not aiming for a specific KfW energy standard but expect to land somewhere between 70 and 55. The heating load calculation is not finished yet since the contract is not signed.

The GC’s standard offer includes the following:
Gas heating: Vaillant auroCOMPACT VSC S 206/4-5 190 condensing compact unit
Rated at 20 kW (wow, why?)
Includes a 190 L (50 gallons) hot water storage tank, plus 2.5 m² (27 ft²) of solar thermal collectors as a package.

Alternatively, he offers an air-to-water heat pump as a substitute for the gas heating and solar thermal system:
Thermia iTec Plus with 9 kW output, cooling function, and a 300 L (79 gallons) hot water storage tank alongside.

I would actually prefer to go with the heat pump, but:

The additional cost for the heat pump solution is a hefty €8,100. For that, we wouldn't need a gas connection...
Maybe I’m mistaken or the math doesn’t add up, but does it really pay off to choose the heat pump?
Even if you achieve a COP of 3.5 or 4, the extra cost of €8,100 minus €2,500 for the gas connection = €5,600 would only pay off very, very late.
At €0.30 per kWh electricity and 10,000 kWh annual consumption with a COP of 4, the cost would be €750. At a gas price of €0.10, the cost would be €1,000. So the difference is €250 per year, meaning the extra cost (ignoring the solar thermal system) would only amortize after 22 years.

Is that correct, or am I missing something / making an error in the calculation? Given the additional cost, I am leaning towards gas, possibly with an extra hot water storage tank.

Thanks and best regards
SoL

Pinkiponk14 Feb 2022 09:04

#25

askforafriend schrieb:

However, the 20 years is usually not reached because most people never maintain their heat pump.

This is also an issue regarding noise emissions, which we took into account during our property search. It may be true that some models are not initially disturbing to neighbors in every case, but if no maintenance is carried out, they will become progressively louder.

CC35BS3814 Feb 2022 10:34

#26

There are two perspectives to consider: Economically, with current prices, it takes a very long time to recover the additional investment. And even if the extra cost seems unreasonable, as a customer, there is hardly anything you can do about it.
On the other hand, the current direction is moving away from fossil fuels. This is also influenced by measures such as the CO2 tax.
Personal opinion (!): Unless there is no other option, I would not install any heating system other than a heat pump today. The path is clear—away from fossil fuels. For amortization calculations, one should take into account the rising CO2 tax as well as fluctuating electricity prices. However, I would clearly rely on electricity, since, in principle, Germany can produce it domestically, and to some extent even by oneself. In contrast, gas has to be imported, and recent fluctuations in gas prices—especially when global politics trigger conflicts—are a clear example of that. There is also a discussion here about gas price increases.

kati133714 Feb 2022 16:08

#27

Mycraft schrieb:

Yes, I know that too. Maintenance is seldom done, and the units usually fail after about 20 years at the latest—if they don’t stop working even earlier.

I’m always surprised by these reference values. Have these devices (air-to-water heat pumps, in this case) even been around that long, and in their current market maturity?
You can't really compare a gas boiler from 1991 to one from 2015. I wonder if the same applies to heat pumps. Those would have to be very early models if they have already been in use for 20 years.

askforafriend14 Feb 2022 16:19

#28

Well, heat pumps contain compressors. Anyone who has a refrigerator knows what that means. I think the same rule applies here: a refrigerator made in 1980 lasted 30-40 years. A refrigerator (or compressor) produced in 2022 will probably stop working right after the warranty period, which is usually 10-15 years 🙂

So much for sustainability...

Mycraft14 Feb 2022 16:44

#29

kati1337 schrieb:

I’m always surprised by these reference values. Have these devices (air-to-water heat pumps now) even been around that long, and in their current market maturity?

I’d say the technology itself is nothing new. It’s like @askforafriend says—a refrigerator turned upside down. What has happened over the last 30 years is mainly an increase in system efficiency at the expense of durability. You know how long refrigerators have existed... and yes, nowadays compressors are usually undersized so they won’t last 30 to 40 years but wear out much sooner and need replacement. Heat pumps are no exception to this.

Benutzer20014 Feb 2022 16:47

#30

kati1337 schrieb:

I’m always surprised by these reference values. Have air-to-water heat pumps even been around that long, and at today’s level of market maturity?

There was a study from Switzerland a few years ago. It stated a lifespan of 20 years for air-to-water heat pumps; currently, the lifespan is talked about as 15–20 years (with maintenance – whatever that exactly means – it could be longer). However, this applies to normally operating units, not machines that cycle frequently, which causes more wear and tear.
Ground source heat pumps have been on the market longer and were reported to last around 27 years.

Therefore, one could say that a heat pump has a similar lifespan to a gas boiler or similar system.

ᐅ Is the additional cost of an air-to-water heat pump compared to gas justified?

Reaktionen