Air-to-water heat pump sizing in new construction

If you are willing to bear the resulting electricity costs, then that is possible with various heat pumps. A heating system that requires such flow temperatures will make you poor with a heat pump – significantly higher operating costs than the old oil heating.

I suspected as much. However, if I install solar on the roof, the costs rise astronomically – as I already reported. In addition, the house is not optimal for solar. At the moment, I have a consumption of about 1,000 liters of oil per year. I find that okay. I am also not fixed on a heat pump.

Oh? Someone here is obviously smarter ... :)

No, it has nothing to do with being smart. It's just about reading a lot. I recommend that too. You are already doing so. 1000l/a really sounds little. Do you heat very sparingly?

I will definitely give feedback on how it looks in practice. :)

So, I can finally report back from practice. Unfortunately, the first result is giving me heartburn again right away. Tomorrow I need to call the heating engineer regarding the wall heating and the overall design. I'm not sure whether either the boss or the employees on site understood the plans.

Target: 3 sqm wall heating 17x2, insulation thickness: 5cm, total heating circuit length approx. 60m



Actual: 2.8 sqm wall heating 16x2, insulation thickness: 10cm and calculated approx. 50m including supply and return.

Do you have any tips on how to best approach the conversation so that the result is optimized from a hydraulics perspective?

I think the 16x2 pipes or 17x2 are not ideal, but mostly negligible. At least from online research, I haven't found any aluminum composite pipe of 17x2, only 16x2. The heating engineer installs only aluminum composite as a principle to be on the safe side.

So far, my plan is:

[*]Call and positively comment on how good I think it is, how quickly things are moving, and that it looks like top-quality work so far.
[*]Then ask about the wall heating, especially why a meander layout and not a spiral, since a spiral considering 5x pipe diameter spacing would be significantly better for installation.
[*]Highlight discrepancies compared to the plan and ask what the reasons might be.
[*]Send the documents again and ask for a discussion of the heating circuits.

Unfortunately, my heating engineer is a typical East Westphalian. I want to avoid confrontation as much as possible and strive for the (for me) optimal outcome. Based purely on the facts, I actually see no option other than dismantling and correction.

Just a quick feedback from me regarding the above-mentioned problem with my wall heating.

Last week, I sent an email to the heating engineer because I had a few questions about the installation planning according to the engineering office and execution planning after I saw the wall heating and asked for a callback.

When there was no response, I called on Friday and we talked for about 20 minutes.

Briefly:
He immediately knew what it was about and said that he personally decided on the 10cm installation spacing. He is aware of the risk of thermal short circuit and would throttle the heating circuit.
The reason for the too large installation spacings is the bending radii, where he has had bad experiences with plaster cracking in the past. When I pointed out that we had commissioned painter's fleece from the painter, he said that would probably not be a problem. The last clients of our main contractor had almost all painted directly on the plaster.
With painter's fleece, he would then correct the wall heating again to 5cm and then offset the bending radii accordingly. Then everything would fit.

I will clarify this again with the site manager next week and then the plaster can probably go on the wall in week 19.

One more update from me:

So far, nothing has changed. The installation spacing of the wall heating is still at 10cm and the site manager wanted an on-site meeting with the heating engineer, site manager, and the general contractor’s boss. I already had a bad feeling about that.

They did everything to make me dislike the 5cm installation spacing.

But what it was actually about is the warranty for cracks. The 5cm wall heating will now be installed, but the issue of cracking is causing headaches for the general contractor. The deal now is that they will do everything possible and, if necessary, embed reinforcing mesh in the plaster to prevent cracks. However, I will sign that I release them from the warranty for the 3sqm in case of cracking.

Then the floor heating installation was discussed in general. Unfortunately, fully installing the floor heating in the shower will not work. The screed will only be done up to about half of the shower by the screed layer, and the rest by the tiler due to the necessary slope for the drain and the partition wall at the end.

I have reluctantly extracted from the site manager that a "Schlenk" floor heating will be installed in the shower as well and that they will pull the screed as far into the shower as possible.



I believe my general contractor has learned a lot about floor heating, flow temperature, installation spacing, and also persistent clients from our build. My wife is very annoyed every time I discuss the topic, but we are paying for the party and have to live with it for the coming decades.

Another update from me:

May I ask why you decided on an air-to-water heat pump and not geothermal? Or was it never up for debate?