ᐅ Looking for a room thermostat for underfloor heating system

Mycraft schrieb:
Individual room controls make sense for fast-responding systems like radiators and buildings with relatively high heat loss.

For underfloor heating and energy-efficient houses, these controls are mostly just decoration.

Unfortunately, that’s true. In our current rental apartment, we have standard wall thermostats for the underfloor heating, and they are pretty much useless. In our house, I will additionally measure the temperature directly on the floor and under the ceiling in the center of the room. This will be implemented using 1-wire and KNX. With a clever script, I want to see if it’s possible to create something meaningful.

The goal is: If the temperature is 20°C (68°F) and I want to raise it to 21°C (70°F), I don’t want it to overshoot to 22°C (72°F) or higher before the underfloor heating finishes regulating. That’s how it is at the moment, and in most cases as well.

Knallkörper schrieb:
But the RTR and the actuator aren’t digital, are they?

Do you mean that they only recognize on/off states? Yes, that’s exactly how it works in about 90% of cases when we’re talking about low-temperature underfloor heating. The heating engineer sets a rough flow rate (if at all), and the RTR then controls the room by shutting off the flow whenever it gets too warm. The downside is that the supply temperature has to be kept higher than necessary all the time, because at any moment an RTR could reopen the flow.

It’s comparable to driving a car that is constantly at full throttle, and you can only control the speed by using the brake pedal (RTR).

Wouldn’t it be more sensible and efficient to apply only as much throttle as needed to reach the desired speed and then maintain it?

Bieber0815 schrieb:
What happens when you change the setpoint for a room?

Nothing.

Steffen80 schrieb:
Unfortunately, that's how it is. In our current rental apartment, we have standard floor heating wall controllers, and they are really ineffective. In the house, I plan to measure the temperature directly on the floor and under the ceiling in the center of the room. This will be implemented using 1-wire and KNX. With a smart script, I want to see if I can achieve something useful.

The goal is: If I have 20°C (68°F) and want to raise it to 21°C (70°F), the floor heating shouldn’t overshoot to above 22°C (72°F) before it is properly adjusted. That’s how it usually works now, and in most cases.

That would only cause overshooting when changing the set temperature. However, I believe Mycraft generally doubts that you can control different temperatures in different rooms using RTR and floor heating. (I wouldn’t agree with that.)

Knallkörper schrieb:
I believe that Mycraft generally doubts that different temperatures can be achieved in different rooms using TRVs and underfloor heating.

No, I don’t doubt that, but in a modern building, temperature differences are minimal, as shown in my picture—about 2–3°C (4–5°F). More than that is wishful thinking... but 2–3°C (4–5°F) can also be achieved without TRVs, as shown in my picture.

Question:

Then what is the purpose of TRVs if I can achieve the same conditions without them?

Mycraft schrieb:
Wouldn't it be more efficient and economical to apply only as much gas as needed to reach a desired speed and then maintain it?

If it really works that way (digital, simply on/off), then the question is about the cycle rate. Assuming the valve needs to achieve 50% flow to reach the target temperature, it would of course be better if it alternates 10 seconds open and 10 seconds closed, rather than 10 minutes open and 10 minutes closed.

I need to clarify today whether we have continuous actuators or solenoid valves... or whatever kind of fitting is installed there.

Mycraft schrieb:
No, I don’t doubt that, but in a modern building, temperature differences of only about 2-3°C (4-5°F) are possible, as shown in my picture. More than that is wishful thinking... but 2-3°C (4-5°F) can also be achieved without demand-controlled ventilation, as you can see in my picture as well.

Question:

So why use demand-controlled ventilation if I can create the same conditions without it?

I see it differently, but that also depends on my personal habits. For example, I like to sleep with the window open even in winter (not just for the cool air, but mainly because of the sounds). I also believe that through our exterior walls and roof area, much more heat energy is lost than what is gained through interior walls and doors (this applies only in winter). It happens less often that I actually want it warm in the bedroom.

So I need at least an on/off switch in the bedroom.