ᐅ Central room temperature controller for the fan coil unit (FCU) of the underfloor heating system

Created on: 23 Jun 2020 11:34
M
micric3
Hello,

Is there a way to control the ERR centrally on one device, so that, for example, the children cannot adjust the underfloor heating control (heating circuit)? Also, I don’t mind not having a thermostat with a controller in every room. What would be the alternative? Are there sensor-only devices that, for example, send the temperature wirelessly to the central unit, or does a separate fixed setting for the respective heating circuit also count as an ERR?

Good luck
M
T
T_im_Norden
9 Jul 2020 12:27
Forget the idea that the heat pump heats individual rooms.

Imagine your entire house with its rooms as one large water circulation system.

Each room has an adjustable inlet that determines how much water flows through it over a given time.

The entire circuit is heated to a set temperature.

To bring a room to the desired temperature, you must allow a certain amount of water to flow through it depending on the room’s size.

If all rooms are the same size, this is straightforward—just allow the same amount of water into each room.

However, rooms are usually different sizes, so you need to adjust the amount of water to suit each room.

You control this through the inlet (distribution manifold of the underfloor heating system, where you can set the flow rate).

Unfortunately, in some rooms, not enough water can flow in to reach the desired temperature (usually bathrooms, since they tend to be small and require higher temperatures).

You can either create space for more water (reduce pipe spacing or use wall heating) or increase the water temperature.

Raising the temperature (known as the flow temperature) brings the required warmth to the bathroom, but now the other rooms also get warmer.

So you need to reduce the water flow there until you reach the desired temperature.

This process is called hydraulic balancing.

However, when outside temperatures drop, this heat may no longer be sufficient.

You might consider increasing the water flow to each room, but then you face the challenge of recalibrating everything to ensure balance, and you remain limited by smaller rooms where less water can flow.

Fortunately, the heating system knows from the outdoor sensor when the outside temperature falls.

It compensates by raising the flow temperature.

Since all rooms were previously adjusted correctly during the hydraulic balancing, this works effectively.

This adjustment is managed by the heating curve, which defines how much the flow temperature must change in response to outdoor temperature variations.

This is a simplified explanation, but it illustrates the basic function.
T
T_im_Norden
9 Jul 2020 12:31
Alessandro schrieb:

Who is supposed to do the hydraulic balancing if I consider the installer incompetent (at least in these matters)?
When should it be done? After the first heating period?

You do this yourself -> thermal balancing.
Carry it out in winter with overcast skies.
It usually takes 2-3 years until it’s right.
face269 Jul 2020 12:34
@T_im_Norden

Respect!!! Finally explained well!!
A
Alessandro
9 Jul 2020 12:53
Ok, great! Thank you all.
And should the outdoor temperature at which the heat pump starts heating be between 10-13°C (50-55°F) for a new build?
Mycraft9 Jul 2020 12:54
Alessandro schrieb:

And the outside temperature at which the heat pump starts heating should be between 10-13°C (50-55°F) in new builds?

That depends on the house. It is not possible to make general statements here.
T
T_im_Norden
9 Jul 2020 12:54
Only you can decide that for yourself.
Try it out; if you get cold because the heating doesn't turn on, set it higher.