ᐅ Air-to-water heat pump combined with underfloor heating is not functioning properly

It is indeed confusing when room controllers are labeled in degrees Celsius. Such a system is not capable of providing that. I believe this is the fundamental misunderstanding.

Tolentino schrieb:

First of all, most of the observations described are actually normal for a modern heat pump with underfloor heating. Furthermore, for efficient operation of the heating system, using individual room control tends to be counterproductive or unnecessary. Usually, you would set the desired temperature directly on the heat pump and the valves at the heating circuit manifold, which then maintain that temperature. Strongly differing temperatures are not possible, or only poorly possible, because everything within the same thermal envelope heats each other.
Bathrooms often have a limited area and a higher heating demand, which typically results in insufficient heating capacity. That’s why additional heaters are often planned. However, with low-temperature systems, it makes limited sense to integrate these additional heaters into the "normal" heating circuit since it operates at low temperatures. You need a large surface area to achieve effective heating output here. It’s usually better to use electrically operated heaters for this purpose. These are available both in classic versions and as towel warmers. You can check (or have it checked) whether your towel warmer can accommodate a heating cartridge. This cartridge is then, for example, inserted at the bottom of the towel warmer and plugged into a socket. Retrofitting is not easy and should be carried out by a specialist.
Alternatively, you can look for other heating options. There are attractive infrared panels, less visually appealing ceramic radiant heaters, or simply classic fan heaters.

So, does this mean I cannot control the temperature in each room individually? If that’s the case, I find it quite disappointing. What’s the use of having temperature controls in every room then? And why did this work in our previous apartment? Could this possibly be related to the district heating connection?
We have towel warmers with heating cartridges that are plugged into the socket. However, I’m not really happy with compensating with that. This makes me wonder whether that investment was a complete mistake.

Mycraft schrieb:

From the original post, I gather that there are no errors. The heat pump is doing exactly what it’s supposed to do.

You can forget about the room controllers. They’re just decorative on the wall. Or, they can act as an emergency override. But in that case, you’d have to run the heat pump at a higher setting than necessary, and who wants that?

The behavior you describe is exactly how a heat pump should function. In your apartment, you probably had underfloor heating that was not operated by a heat pump, which also explains your surprise that it worked there but not in the house. Am I correct in assuming that?

Regarding the apartment, you are right. It worked there because district heating was connected?
Regarding the emergency override, I couldn’t detect that either, even when the set room temperature was 23°C (73°F). Although the temperature controller indicated no heating, with open windows we still had 22–23°C (72–73°F), meaning the underfloor heating was active even if we hadn’t set it.

guckuck2 schrieb:

It is indeed confusing when the room controllers are labeled in degrees Celsius. Such a system is simply not capable of delivering that.
I think this is the fundamental misunderstanding.

Unfortunately, no one explained that to us. However, the analog controllers also displayed temperature numbers, and we had that in the apartment as well.

_Ugeen_ schrieb:

So does this mean I cannot control the temperature individually in each room?

No, but first, not by more than 2-3 degrees difference, and second, only with a loss of efficiency, because adjacent rooms with a higher desired temperature will warm the other rooms.
Secondly, with an efficient system, you don’t adjust the desired temperature every day on a (poor) controller; instead, the heating is designed from the start for the target temperature. This includes determining the flow rate and pipe spacing for a predefined supply temperature, which should be kept as low as possible.

_Ugeen_ schrieb:

If that’s the case, I think that’s very bad.

Your builder or heating engineer probably gave you poor advice or just did the bare minimum.

_Ugeen_ schrieb:

Then what use are temperature controllers in every room?

They have no real use, but they are legally required. Exemptions seem complicated and unlikely, although possible (according to experiences shared here in the forum).
Ultimately, the recommendation here is either to ignore the individual room control (set to permanent maximum) or even deactivate it by unscrewing the actuators on the heating manifold or cutting power to them (if powerless: set to open).

_Ugeen_ schrieb:

Then why was it possible in our apartment? Could it be related to district heating?

Something along those lines. District heating water arrives at the heat station in the building at 70-90°C (158-194°F). This means the flow temperature at your heating manifold is at least 60°C (140°F). This heats the floor thoroughly and at full opening it’s actually already too warm.
Currently, in my own condominium, I have controllers that display five levels but basically only recognize on and off. That means if I increase them, it actually gets too warm, especially in the transitional season, so I have to adjust several times a day or just run full heating in the bathrooms and only when needed in the other rooms.
Since the heating water is already this hot, efficiency is low anyway, so losses remain limited.

_Ugeen_ schrieb:

We have towel radiators with electric heating elements plugged into sockets. Balancing this out that way doesn’t seem very good to me. I wonder if that investment was a total mistake.

No, that’s exactly the right approach. You have to cover short-term additional heating needs electrically. Raising the entire system’s flow temperature to then throttle the flow rate in all rooms except the bathrooms will cost you much more in the long run than running the electric heating element for 15 minutes in the morning and evening.

_Ugeen_ schrieb:

Although the temperature controller showed no heating, with the window open we had 22-23 degrees (72-73°F), which means the underfloor heating was still active, even though we didn’t set it.

Without knowing all the settings of the entire heating system, there are many possible reasons for that. Was sunlight maybe shining in?

_Ugeen_ schrieb:

Unfortunately, no one explained that to us. The analog controllers also show temperature numbers, which we had in our apartment as well.

Yes, unfortunately, explanations are often lacking. The temperature numbers on analog controllers are purely decorative and probably meaningless.

Underfloor heating systems are too slow to respond due to the thermal mass, also known as the heated screed, to allow effective room-by-room temperature control. This might work somewhat better with very high supply temperatures and poor insulation, but less so in new buildings and with heat pumps. E

Tolentino schrieb:

No, but first, not by more than a 2 to 3-degree difference, and second, always with a loss of efficiency because the adjacent rooms with a higher desired temperature end up heating the other room.
Secondly, with an efficient system, you don’t adjust the desired temperature every day using a (poor) controller; instead, the heating is designed from the start for the target temperature. This includes determining the flow rate and the pipe spacing for a predefined supply temperature, which should be kept as low as possible.

So I end up with a bedroom that is always warm, which I don’t want...

Tolentino schrieb:

Your construction company or heating installer just gave you poor advice or did the bare minimum required.

Definitely!

Tolentino schrieb:

Nothing, but these (single-room controls) are legally required, and being exempted seems complicated and unlikely, although possible (based on forum experience reports).
Ultimately, the recommendation here is to either ignore the single-room control (leave it permanently at the maximum setting) or even deactivate it by unscrewing the actuators at the heating circuit manifold or switching off the power (if switched off: leave it ON).

Sorry for the silly question, but how and where do I switch off the power then?

Tolentino schrieb:

Something like that. District heating water arrives at the heat station in the house at 70 to 90°C (158 to 194°F). That means the supply temperature at your heating manifold is at least 60°C (140°F). This will definitely make the floor warm, and when fully on, it’s actually already too warm.
Currently, for example, in my condominium, I have controllers that display five levels but basically only operate on/off. That means when I turn them up, especially during transitional seasons, it tends to get too warm, and I end up adjusting them several times a day or just have full heat in bathrooms and really only heating other rooms when needed.
Since the heating water is already so hot, efficiency isn’t very high, so heat loss is somewhat limited.

We probably should have opted for district heating.

Tolentino schrieb:

Without knowing all the settings of the entire heating system, there are many possible reasons. Was the sun shining, by any chance?

Which settings or values would be important to know for a reasonable assessment?

_Ugeen_ schrieb:

So, I have a bedroom that is always warm, which I don’t want...

Not necessarily. You can, of course, reduce the flow rate at the heating circuit valve (HKV) for the bedroom until you reach your desired temperature.

_Ugeen_ schrieb:

Sorry for the silly question, but how and where do I switch off power?

Not a silly question, because there is no switch for that. You actually have to disconnect the cables from the actuators. Not everyone does that without consideration.
The first step should be to contact your heating engineer to perform a hydraulic balancing if it hasn’t been done already. Then you can look up “thermal balancing” here or generally online. This is a complex topic that can take days or even weeks, because a floor heating system, as @michert mentioned above, responds very slowly.

_Ugeen_ schrieb:

We probably should have chosen district heating instead.

I don’t think so. District heating has a clear advantage: it saves space in the utility room.
Disadvantages include: dependence on a monopolistic supplier, both financially and technically,
as well as higher consumption costs and an inefficient heating system.

_Ugeen_ schrieb:

Which settings or values would be important to provide a reasonable assessment?

See above: “thermal balancing.”
Otherwise, you need professionals who are more than well-informed amateurs.
Maybe @Daniel-Sp will check in here again; he’s quite knowledgeable.