Air-to-water heat pump sizing in new construction

So, I have the feedback from the engineering office regarding the smaller Vaillant. He increased the flow temperature from 33 to 33.5°C and the return temperature from 29 to 28.5°C, so the spread from 4 to 5 K.

Now the volume flows are lower, and the small 75/6 A from Vaillant can deliver the volume flow.



Let's see how I can optimize this in the long term. It almost feels like an old building with 34°C flow temperature when I compare the benchmarks here with you. Our building with gable and bay window plus the many floor-to-ceiling windows really seems to make a big difference. But I hope for good solar gains in practice, so that I can reduce the flow temperature over the years.

The only shame is that I can't get the small 55/6, which would be perfect for our heating load, to achieve an annual performance factor of 4.5....

I just wanted to give a practical feedback on the calculation.

Overall, I am very satisfied. I managed to have the bathroom as the warmest room with a heating curve of 0.2 and a setpoint temperature of 21°C (foot point or parallel shift, I'm not sure – standard 20°C). I can't reach 24°C, but about 23°C, which is noticeably warmer than the rest.

The living room is still too warm, but our loft door is missing, so we still have draft to the open stairwell/hallway. The living room temperature is about 22°C, which is comfortable under the circumstances. I might be able to reduce this a bit once the door is installed and more flow remains for the bathrooms.

Experience in the last few days with constant temperatures between 1-5°C during the day without sun. Also no problems with occasional frost. I see this as confirmation that the stress with the heating load calculation, design of the underfloor heating and wall heating was worth it.

I’m curious about the real winter and the next winter when our building structure has dried out. Actually, I wanted to run the first year with the wall thermostats, but I couldn’t resist and did the hydraulic balancing. And it paid off!

Surprisingly quiet here in the thread. :)

Noticed a small problem:



Pages of discussion here about the optimal design of underfloor heating in the bathroom. In the parallel thread about Arotherm, trying to squeeze out the last bit of efficiency, and then THIS....

2 sqm or an estimated 30% of the heating surface have to be covered by a fluffy carpet. No other way. It has to be that way.

Gives you a headache.

Invoice made without the woman? ;)

If you have relatively constant room temperature, the carpet shouldn't make a difference, right? I would think that the thermal conductivity is more interesting with faster temperature changes. But I have absolutely no sense for the orders of magnitude...

Touch your head.

Why? Where is the problem? Whether the carpet is there or not is so irrelevant. Except for the eye - that doesn't feel so good ;)

Yes, makes a big difference. Requires about one degree higher flow temperature for the same heat input.