ᐅ KfW 55: Choosing the Heating System – Gas vs. Air-to-Water Heat Pump
Created on: 21 May 2021 18:29
G
Gerddieter
Hello everyone,
we recently spoke with the general contractor about the quote for a KFW55 single-family house.
We’re uncertain about the heating system. According to the contractor, for the subsidy we need either an air-to-water heat pump or a gas boiler combined with a ventilation system and solar thermal.
The contractor couldn’t clearly explain the pros and cons, only that the air-to-water heat pump is more commonly used and the gas combination with ventilation is more expensive (but then you do get ventilation and solar thermal).
We would prefer to avoid having the air-to-water heat pump unit installed in the garden, but are generally open.
Could you please share your opinions on the advantages and disadvantages?
Thanks,
GD
we recently spoke with the general contractor about the quote for a KFW55 single-family house.
We’re uncertain about the heating system. According to the contractor, for the subsidy we need either an air-to-water heat pump or a gas boiler combined with a ventilation system and solar thermal.
The contractor couldn’t clearly explain the pros and cons, only that the air-to-water heat pump is more commonly used and the gas combination with ventilation is more expensive (but then you do get ventilation and solar thermal).
We would prefer to avoid having the air-to-water heat pump unit installed in the garden, but are generally open.
Could you please share your opinions on the advantages and disadvantages?
Thanks,
GD
T
T_im_Norden22 May 2021 09:39They are only similar if you include the subsidy or install a Geisha heat pump yourself.
A chimney is not necessary; a LAS (likely referring to a heat supply system) is sufficient.
A chimney is not necessary; a LAS (likely referring to a heat supply system) is sufficient.
G
Gerddieter22 May 2021 10:23Bookstar schrieb:
I’ve already calculated it here before, the annual costs with gas are at least one third lower. And this is based on a very efficiently set heat pump, not mine 😀. Hi, could you please share the link to the calculation?
GD
nordanney schrieb:
In the end, both systems are quite similar in terms of initial cost. Of course, you can try to put a positive spin on it. But that doesn't change what has already been described and reported many times here and elsewhere. A gas boiler with everything included—meaning the unit, storage tank, LAS (not to be confused with a "real chimney"), installation, connections, settings, and so on, truly everything except the gas connection (which varies from municipality to municipality)—costs roughly about one-third of a complete air-to-water heat pump system when it comes to investment costs. Even when you include the gas connection (if it’s already available in the street and doesn't have to be extended 50–100m (160–330 ft) over open land) and a basic solar system, you end up paying around half to two-thirds of the heat pump’s cost.
Of course, if you don’t want or can’t do any of the work yourself, other numbers are possible.
The real challenge comes afterward—not infrequently, you have to intervene with the heat pump yourself because standard settings or excessively high heating curves are often used, so the homeowner ends up adjusting the system during the first or even second heating season. Otherwise, the system might cause excessive heating and waste energy.
There are plenty of experiences and reports on this, not only here in the forum.
Also, the CO2 tax barely changes anything so far (including all planned increases). A modern system emits about 1.5–2 tons of CO2 annually, which translates to an additional cost of around 50 euros per year in 2021 and about 110 euros in 2025. That’s negligible; it still takes roughly 10 years of gas consumption costs to break even compared to the initial investment for an air-to-water heat pump (without subsidies).
Don’t get me wrong—heat pumps are a great technology. Besides running three of my gas boilers, I also operate four heat pumps (and have two more waiting to be installed). But many factors have to come together for a heat pump to make economic sense.
guckuck2 schrieb:
Oh yes, calculations by bookstar are always entertaining Yes, especially because they are realistic and not sugar-coated like those from the heat pump lobby or some nerds.
@gerd I’ll look it up later.
Similar topics