Ecologically built house with wooden facade - Features

Don’t get me wrong: I find heat pumps fascinating technology and would like to have one too if the conditions are right. Unfortunately, that’s not the case for us with a house built in 1983 and 400m2 of space, despite KFW100EE renovation. The difference to the geothermal heat pump with 4 boreholes and pellet system was more than 20k euros before subsidies. That makes the pellet system simply more sensible as the "least evil climate option." A large part of the old building stock in Germany is not easily suitable for an air-water heat pump. Period. Unless you want to pay an arm and a leg.

It may be that pellets were the most economical option for you, but what’s with the talk about a large part of the old building stock when it’s specifically about a house from 1996 that would already be well insulated with a few new windows? No one claims it makes sense to install heat pumps in unrenovated old buildings. However, in combination with appropriate insulation and conversion to underfloor heating, it is usually the best alternative.

Thank you again for the lively discussion, it gives me a lot to think about (and homework). Besides work, there was another viewing appointment today, hence the late response. Also, the parents-in-law have gotten involved with a somewhat curious plot/house construction proposal. If anything comes of it, I would probably ask for advice here in the forum again ;)

it would be pretty stupid if FIRST the seller rips out and replaces the functioning heating system from the house presumably well thought-out 25 years ago instead of canceling and reducing the price accordingly ... ... and then after a winter of freezing invest AGAIN in the heating system wouldn’t something like €10,000 or more be burned up quickly with such a "two-stage" approach?

Yes, that would indeed be a stupid situation. If it comes to that, I will ask again how far the order for the air heat pump already is (if I remember correctly it has been ordered for a while but due to delivery delays has not yet been installed). But I don’t want to "alarm" the sellers with that now.

That the new heat pump is supposed to be able to do 70° speaks for a modern heat pump with R290 as refrigerant. That’s already half the battle, those things run really well. Add a maximally large photovoltaic system on the roof, new windows at some point, then it will work out.

I have just learned that it is a Wolf CHA-10, so as suspected with R290 and quite large dimensioned for me as an absolute layman?

I am happy to give my two cents here. The wall structure is absolutely fine for the year it was built and is still mostly done that way today. 60x160mm frame with mineral wool or cellulose blown insulation is still standard today as well, alternatively wood fiber boards can also be used. [...] The only thing done differently today is the installation level (about 6 cm, which is again insulated with wood fiber or stone wool. Usually, an OSB board is screwed onto the frame from the inside as an airtight bonded layer (= vapor barrier) and the installation level is applied there.

Thanks for the information, that sounds good! I will watch the mentioned YouTube channel in due course!

As far as it is also true in reality that the owner has made more profound considerations each time, I cannot imagine that he would have had any heating equipment installed. If I were to sell my house or as I had it, I was able to explain to the interested party exactly why I had decided something that way. The interested party may then like it or not.

I have now learned that it is a Wolf CHA-10, so as suspected with R290 and quite large dimensioned for me as an absolute layman?

No, given the values and probably no further adjustments to the heating system have been made, and also with radiators, it should be fine. The smaller 7 model only goes down by 30%.

I can reassure you regarding the wooden floor: I have now been living in various apartments with wooden floors for almost 15 years. From vomiting students to spilled strawberry shakes and now 2 years of continuous mess caused by our little son during meals, no lasting damage has been left. What is rather critical are things like small stones brought in from outside or desk chairs without protective mats.

It may be that pellets were the most economical option for you, but what's the point of talking about the majority of old buildings when it's specifically about a house from 1996 that would already be properly insulated with a few new windows? No one claims that it's sensible to install heat pumps in unrenovated old buildings. However, in combination with appropriate insulation and conversion to surface heating, it is usually the best alternative.

I never said anything else? The heat pump is a great technology that works super well in many new buildings.

"A large part of the old building stock in Germany is not readily suitable for an air-to-water heat pump." That cannot be disputed. So for me, replacing all glass elements and subsequently installing underfloor heating plus an air-to-water heat pump is no small matter if you can't do it yourself (hence "not readily"). Costs can very quickly add up to the higher to high five-figure range to properly prepare a house built up to around the 90s for an air-to-water heat pump! I have just gone through all of this myself for a large single-family house built in 1983.