What flow temperatures are you currently running?

In the end, nothing had to be throttled, the flow rate remained at maximum everywhere.

Then you were lucky with the design of your underfloor heating. Or you have a good heating engineer or planner.

Enviable. Had a good plumber?

Surely there are worse ones. It was calculated room by room. The pipe length/density is certainly the key to success, the temperature level you choose yourself.

However, the equation only works because we agree on a homogeneous temperature. There are said to be people who sleep at 19 degrees and want to stand in the bathroom at 24 degrees. You have to take that into account in the pipe lengths/density and/or increase the flow temperature and then throttle room by room.

There are said to be people who sleep at 19 degrees and want to stand in the bathroom at 24 degrees. This must be taken into account in the pipe lengths/density and/or the flow temperature increased and then throttled room by room.

That is why the desired room temperatures are determined in advance, so nothing has to be throttled.

In the tables are the calculated circuit lengths and to the right the installed length; in any case, the installer scribbled it like that on the distributor.

Hello Lesmue, according to your table, a volume flow of 14.3 l/min = 858 l/h was calculated. Are you still below the maximum possible volume flow of the heat pump? After your throttling, you are below 500 l/h. That is a really drastic reduction of the volume flow. Can you say something about that? Or are my numbers not correctly represented? It was already close to 0 degrees early on with us. What heating load/heating output was achieved then? How far has your heat pump (Vaillant Arotherm Split 3.5 KW?) throttled down?

The problem is that it is a standard GU/prefabricated house provider design. The heating load is calculated at 3.2 kW at -12°C, but the error alone lies in the fact that the controlled residential ventilation was not taken into account in the heating load.

Transmission losses are 2424 watts, plus 752 ventilation losses, totaling 3176 watts. If I now assume a heat recovery of 70% in the controlled residential ventilation, the ventilation loss is reduced to 225 watts, which then again means a total heating load of only 2649 watts.

The underfloor heating is of course designed accordingly for the full 3176 watts, whereby rooms are included that were calculated with 20°C but in reality should only reach e.g. 18-19°C (WC, guest, bedroom, hallway).

The utility room can be completely disregarded because it is already too warm due to external heat (inverter, heating circuit distributor, etc.) despite the underfloor heating being switched off.

Accordingly, the actual volume flow is correspondingly lower compared to the calculated one.

That the design of the underfloor heating is for the feet is shown by the WC circuit: how on earth are you supposed to set 0.3 liters on a Taco setter valve? The calculated flow velocity in this circuit is by the way 0.0 m/s.

In the guest room then at 0.8 L/min it is 0.1 m/s. The whole system is designed for a maximum 30°C supply temperature.

That is why many Taco setters also look as if they have zero flow; according to calculations, I have hardly any adjustable flow at 20°C, and in reality, since I only want 18-19°C, even less.

I have already written that I completely closed the circuits once and then reopened them until a minimal stop became apparent. But you can hardly see it because I think the Taco setters only show 0.5 l/min properly.