ᐅ Underfloor heating and radiators – two thermostats in one room
Created on: 26 Mar 2020 20:43
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B.Baumeister
Hello everyone,
I have a single-family house built in 2019. There is underfloor heating everywhere except in the bathrooms, where it is supplemented by radiators. Otherwise, the heating surface would not be sufficient, I was told. This way, the rooms get as warm as I want. But now I have two thermostats: one electric thermostat for the underfloor heating and one mechanical thermostat on the radiator.
Now my questions:
1.) What is the best way to regulate the heat? Should I set the radiator to 5 and then control the temperature via the room thermostat? Or the other way around? I am not entirely clear about how the two work together.
2.) Thinking one step further: Could I use the room thermostat and underfloor heating to maintain a base temperature, and then have the radiator provide additional heating as needed? Possibly with a timer control.
Thank you in advance.
Enrico
I have a single-family house built in 2019. There is underfloor heating everywhere except in the bathrooms, where it is supplemented by radiators. Otherwise, the heating surface would not be sufficient, I was told. This way, the rooms get as warm as I want. But now I have two thermostats: one electric thermostat for the underfloor heating and one mechanical thermostat on the radiator.
Now my questions:
1.) What is the best way to regulate the heat? Should I set the radiator to 5 and then control the temperature via the room thermostat? Or the other way around? I am not entirely clear about how the two work together.
2.) Thinking one step further: Could I use the room thermostat and underfloor heating to maintain a base temperature, and then have the radiator provide additional heating as needed? Possibly with a timer control.
Thank you in advance.
Enrico
D
Daniel-Sp26 Mar 2020 21:46Hello.
What supply temperature is the heating system running at?
Are the underfloor heating and radiators connected to the same circulation pump, or are they controlled separately?
How is the hydraulic system arranged? Is there a mixing buffer tank?
If you notice a difference between operation with and without radiators, you probably have a (too) high supply temperature. This can cause the underfloor heating loops to be shut off via the ERR, leading to short cycling of the heat pump, which is extremely inefficient and puts undue stress on the equipment.
Please provide more information about the entire system and the heating load calculation.
Best regards
What supply temperature is the heating system running at?
Are the underfloor heating and radiators connected to the same circulation pump, or are they controlled separately?
How is the hydraulic system arranged? Is there a mixing buffer tank?
If you notice a difference between operation with and without radiators, you probably have a (too) high supply temperature. This can cause the underfloor heating loops to be shut off via the ERR, leading to short cycling of the heat pump, which is extremely inefficient and puts undue stress on the equipment.
Please provide more information about the entire system and the heating load calculation.
Best regards
B
B.Baumeister27 Mar 2020 07:21As far as I can tell, there is no separate pump for the two radiators. I just checked and the supply temperature is 28.7°C (84°F).
I even have the heating load calculation in digital form, but as a layperson, I obviously don’t understand it.
Regarding the hydraulics: during installation, the company apparently used a pre-calculated setting for the hydraulic balancing. This resulted in the ground floor staying cold because the flow regulators were only opened to 25%.
I then contacted the heating company’s customer service, who noticed this.
He said that hydraulic balancing is a nice idea in theory but often leads to the opposite in practice.
He then fully opened all the regulators, and since then it has been working fine.
When I say I notice when the radiators are supporting the heating, they are still only lukewarm.
But as an example: last night I turned the radiator down to zero and left the room thermostat setting as it was in the morning before, which showed over 23°C (73°F). Without the radiator, it was 22°C (72°F) this morning, and the room thermostat still indicated a deviation from the target temperature.
I explain this by assuming that the radiator’s surface area is simply enough to compensate since the bathroom is relatively small. It has 10 sqm (108 sqft) – bathtub and shower. So maybe about 8 sqm (86 sqft) can serve as the heating surface. The radiator has 0.72 sqm (7.75 sqft), multiplied by three (front, back, and the space between).
Well, I’ll leave the radiator at 5 now and let the room thermostat manage the control. The heating system service is due soon, so I’ll interview the technician then.
Thank you all.
I even have the heating load calculation in digital form, but as a layperson, I obviously don’t understand it.
Regarding the hydraulics: during installation, the company apparently used a pre-calculated setting for the hydraulic balancing. This resulted in the ground floor staying cold because the flow regulators were only opened to 25%.
I then contacted the heating company’s customer service, who noticed this.
He said that hydraulic balancing is a nice idea in theory but often leads to the opposite in practice.
He then fully opened all the regulators, and since then it has been working fine.
When I say I notice when the radiators are supporting the heating, they are still only lukewarm.
But as an example: last night I turned the radiator down to zero and left the room thermostat setting as it was in the morning before, which showed over 23°C (73°F). Without the radiator, it was 22°C (72°F) this morning, and the room thermostat still indicated a deviation from the target temperature.
I explain this by assuming that the radiator’s surface area is simply enough to compensate since the bathroom is relatively small. It has 10 sqm (108 sqft) – bathtub and shower. So maybe about 8 sqm (86 sqft) can serve as the heating surface. The radiator has 0.72 sqm (7.75 sqft), multiplied by three (front, back, and the space between).
Well, I’ll leave the radiator at 5 now and let the room thermostat manage the control. The heating system service is due soon, so I’ll interview the technician then.
Thank you all.
D
Daniel-Sp27 Mar 2020 12:10Unfortunately, you remain somewhat vague about which components were installed and how they are connected.
What type of heat pump do you have?
How long is the duration of a heating cycle?
What type of heat pump do you have?
How long is the duration of a heating cycle?
B
B.Baumeister27 Mar 2020 13:41I’m not being vague; I’m just a layperson and simply don’t know more about it.
I have a Rotex HPSU Compact 308.
I have a Rotex HPSU Compact 308.
There’s no need to overcomplicate this. Without the radiator, it’s too cold, so set it to 5 and always run it together with the underfloor heating. Of course, a radiator that’s warmer than the air will also warm the room. Essentially, it just increases the surface area of the underfloor heating.
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