ᐅ New Construction – Uneven Underfloor Heating (Vaillant Aurocompact)

Hello everyone,

We moved into our newly built single-family house 20 days ago (120 m2 (1,292 ft²) living space, tiled floors and underfloor heating throughout the ground floor and upper floor, completed in December 2020). We have now noticed that the underfloor heating (ground floor and upper floor), which is operated via a Vaillant aurocompact solar gas condensing system + control unit "multimatic VRC 700/6" + room thermostats in every room, apparently does not really heat or does not heat sufficiently well.

The problem: The floor is noticeably warm only in some rooms (slightly), no matter if we set a desired temperature of 23, 25, or 28°C (73, 77, or 82°F). We also have the impression that it takes a very long time (about 15–20 sec) until warm water comes out of the taps.

The operating mode is set to "Auto" for both "Heating" and "Hot water."

"Zone 1" (heating) is currently set to 25°C (77°F) from 00:00 to 24:00.

All room thermostats are set to "standard" (medium heat).

In addition, we have two heating manifolds in the house (one in the utility room on the ground floor and one in the hallway of the upper floor).

I do not initially assume that there is a defect in the system itself. Rather, I suspect user error on my part due to a lack of knowledge.

Does anyone have an idea what the problem might be or how I can achieve even underfloor heating in all rooms?

Will it get warm enough in the rooms?
With a modern underfloor heating system, the floor itself does not get very warm because the supply temperatures are low.
Otherwise, please read up on the topic of hydraulic balancing.

I find that the floor is already warming up, noticeable in some spots (for example, comfortable with bare feet), but it doesn’t seem to reach around 28°C (82°F); it didn’t feel that warm in the rooms when I left the setting on for about 30 hours.

Is it possible to perform hydraulic balancing yourself, or would that be too complicated?

You have to carry out the hydraulic balancing yourself since it is a longer process. It’s not complicated, but you do need to study the topic thoroughly. There are several threads in this forum where it is explained.

You didn’t answer whether the room temperatures (not the floor) are appropriate.

In the photo of the heating circuit distributor, you can see that all flow indicators are at the top, meaning there is no flow.

It is possible that the photo was taken at the exact moment when all valves were closed, or there might be an error here. Perhaps the control valves NC (normally closed) and NO (normally open) were mixed up.

The image does not provide any information at all, especially since we do not know when it was taken.