Air-to-water heat pump sizing in new construction

Isn't it required by the Energy Saving Ordinance that all rooms within the thermal envelope must be able to be heated above a certain size?
Apart from that, I see it exactly like my predecessors. Heat flows from the warm rooms into the cold rooms, which leads to an increased heating load of the warm rooms, which in turn leads to a higher supply temperature. Heat pumps operate less efficiently, and heating becomes more expensive at the same room temperature.

That is theory and definitely not the case in practice. I have gathered enough experience myself. Especially in the basement, I would only heat as much as necessary, i.e. the living areas. Heating storage rooms would be madness, just like you don't heat your pantry on the ground floor.

In the insulated basement, you always have around 18 degrees year-round. During the winter months, you will then have about 2 to 3 degrees more in your heated rooms.

We have implemented it this way and it is really great!

We have not considered any further subsidies in our financing - except for the KFW funding. So far, the general contractor always wanted an unrealistic surcharge for BAFA-eligible devices that would almost completely cannibalize the subsidy. Nevertheless, I entered a standard Daikin Altherma 3 R F into the annual performance factor calculator and, with supply/return temperature VL33/RL28 and hot water at 27% according to the KFW calculation, I come to an annual performance factor of 4.6.

That means to me that, on the one hand, I have to push my heating technician all the more to install the underfloor heating according to the calculation. On the other hand, I could also compensate any additional costs for wall heating and extra efforts for installation through the BAFA grant and still have a very decent extra amount left, or am I seeing this completely wrong?

But in the insulated basement, you always have around 18 degrees all year round. In the winter months, you will then have about 2 to 3 degrees more in your heated rooms.

We implemented it that way and it is really great!

That's basically how I had imagined it. That it’s energetically nonsense, well...

So, since a window has now been removed on our side, we need 45 watts less heating load in the living-dining room. Therefore, I had the design updated again and also worked on the large overlap. This is how it looks now.







I now see this as a concession to the heating installer so that he can lay it much more easily on the ground floor. Fewer heating circuits and significantly larger pipe spacing.

A striking note from the engineering office was that I definitely have to pay attention to the compliance with the areas/pipe spacings on the upper floor. Especially the wall heating in the upper floor bathroom.

you really know your stuff and are currently assisting . You are also currently discussing the pressure losses and the pump flow rate there. Does this look unusual here?

I hope that when it finally starts soon and I can get to the thermal balancing, I’ll be as much of a pro as you. I already see myself optimizing the heating curve and flow rates for weeks in winter.

The heating circuits are partly too long for me. Unfortunately, I can't help you with the pressure drop. Up to 6000 Pa is definitely not a problem, you are only slightly above that. The question is whether the 5cm actually works that well. Be sure to have it written down how many meters of pipe were actually installed in each heating circuit, that is very important. Have you looked at the data sheet of the heat pump, is the nominal volume flow achieved?

But it actually looks quite good... the too long ones over 100 are really only in the basement, where it's not a problem to get it warm anyway, and it doesn't have to be overly warm in the bedroom either. Everything else up to 90 is in the green zone. Above all, it's good that there are no circles that are too short.

The heating circuits would be partly too long for me. Unfortunately, I can't help you with the pressure drop. Up to 6000 Pa is definitely not a problem; you are only slightly above that. The question is whether the 5cm actually works that well. Make sure to have documented how many meters of pipe were actually laid in each heating circuit; that is very important. Have you looked at the heat pump's datasheet? Is the nominal volume flow achieved?

Thanks for the feedback. We will first make an appointment with the heating installer soon. It will probably be a Daikin Altherma 3 R F, but I can't find any datasheets for it. I will definitely demand that from the installer.

Regarding the pipe spacing, I am also curious. I am somewhat reliable; he said that between 5 and 8 cm would be standard or at least not unusual for him in the bathroom.