Air heat pump or use gas and solar?

The price difference between solar & gas also seems quite small to me. In exemplary sample calculations, it's always tens of thousands of euros in favor of gas & solar, but for me only about €2,100 - €2,600.

In our case, the air-to-water heat pump was cheaper than the gas option. Influencing factors: purchase from the developer, rather inexpensive air-to-water heat pump, and additionally a high quantity ordered by the developer.

With the air-to-water heat pump, the gas connection and solar thermal (which is usually installed together with gas due to legal requirements) are omitted. Otherwise, everything is the same (underfloor heating). If you have your energy consultant calculate again (and think it through!!), it could turn out that you are allowed to have gas without(!) solar thermal(!). The most important factor is your controlled residential ventilation (which you want anyway). If that works, gas is IMHO certainly cheaper than an air-to-water heat pump. Then you have to decide what is important to you (investment costs, operating costs, ...).

In the offer, they write air heat pump.

If underfloor heating is included, then it is an air-to-water heat pump (air-to-water heat pump).

Energy from groundwater is a water-to-water heat pump and the most effective thing you can have. Very good!

So in the system, the groundwater level must be taken. Which office do I have to call to clarify on Monday whether we are allowed to do something like that? If that is the best solution, I should at least check if it is feasible.

It's a pity that the general contractor makes the surface collector (or trench collector) so damn expensive. Both the collector costs and the earthworks are totally exaggerated.

He estimated the earthworks. As the builder, I have to commission the earthworks. But even with the €35,000 he calculated for earthworks to prepare the site, he was very close to the truth.

We heat about 250m² of living space. On the internet, it is said that you need about twice the area as collector surface. It must not be asphalted, and no tree, no pool etc. can be there. That would be 500m². I can imagine that a lot has to be plowed up. But I think with such a huge area it does not make sense to restrict oneself so much.

In our case, the air-to-water heat pump was cheaper than the gas option. Influencing factors: purchase from the developer, rather cheap air-to-water heat pump and additionally high quantity through the developer.

Our developer also orders large quantities of Waterkotte devices. You can also get any other heat pump there, but at different prices.

Because of the area of the collectors, I just proposed the trench collector. Apart from development restrictions, it has no limitations. But the topic is off the table.

The water-to-water heat pump is used very rarely in proportion.

You need two wells. Water is taken from the first, which goes through the heat pump, energy is extracted and reintroduced into a second well.

That means the first well must be sufficiently productive and the second must be able to receive the water again.

So there will also be drilling costs for you.

Furthermore, the water must have a certain quality. Otherwise, there can be significant problems with the heat pump.

In addition, the (I'm not sure) lowest water authority must cooperate. Whether they will, no idea.

I don't want to offend you, but is it possible that the general contractor is overcharging you? Obviously, you are getting everything from one source and he is making a lot of money off you.

The earthworks for flat collectors are possibly 2x5 hours, provided that the excavated material can be stored. The offer is considerably overpriced. And you will surely find your own excavator with a driver.

I don't mean to offend you, but could it be that the general contractor is ripping you off? Obviously, you are getting everything from one source and he is making a lot of money off you.

Of course, you always have to be careful with GCs. I had several house offers for this project and this was the most attractive, and our construction consultant also said it was a very fair offer at a good price. Questioning some individual items here and there and discussing them is another matter. Even the credit amounts for trades to be outsourced are fair, and the consultant knows them to be significantly lower.

Even two independent architects we consulted said that with that price we couldn’t build our house with them; better to take the GC specialized in single-family houses.

The earthworks for flat collectors are possibly 2x5 hours, provided that the excavation material can be stored. The offer is considerably overpriced.

The costs for the earthworks were estimated by the GC. He doesn't make any money on that, not a single euro, as I have to award the earthworks myself; they are not part of the contract for work. They say what they need, and I have to get offers for that. That was also the case with the "normal" earthworks. And the estimate was quite accurate—there were also significantly more expensive offers.

I basically think an air-to-water heat pump is fine. The heating load is not enormous (and even if it is, the units are available for practically every heating load), and if modulating, it also fits with the coefficient of performance with the correct configuration of the overall system. A trench collector plays to its advantages (especially in terms of own contribution) financially, and compared to the surface collector, there is not as much digging required.

Ah okay, the prices don’t suggest that to me. But it seems to be common then. In that case, I have nothing to say.