Just out of curiosity, to better understand the slope of the heating curve, what flow temperatures do you typically run at 0°C (32°F) outdoor temperature, given a certain indoor temperature and insulation level, when using a combination of underfloor heating and a heat pump?
Background of the question:
My logic tells me that if I want, for example, 22°C (72°F) room temperature, the flow temperature must be at least 22°C (72°F) or higher, since I learned that there needs to be a temperature difference for heat transfer to occur.
So if my heating system turns on at 12°C (54°F) outdoor temperature, my flow temperature should logically start somewhere around 22°C–25°C (72°F–77°F). Accordingly, at only 5°C (41°F) outside, it should be around 27°C (81°F), and at 0°C (32°F) close to 30°C (86°F).
The system design usually takes the location and outdoor temperature down to about –12°C (10°F). If at 0°C (32°F) flow temperature is already 30°C (86°F) according to my logic, then at –12°C (10°F) the flow temperature should be about 40°C (104°F). But most underfloor heating designs for heat pumps are based on a maximum flow temperature of 35°C (95°F).
Of course, the insulation of the house and the indoor temperatures still play a role. Or is the increase in flow temperature actually so gradual that it only rises by about 0.5–1°C (1–2°F) for outdoor temperature drops in 0–5°C (0–9°F) increments?
Background of the question:
My logic tells me that if I want, for example, 22°C (72°F) room temperature, the flow temperature must be at least 22°C (72°F) or higher, since I learned that there needs to be a temperature difference for heat transfer to occur.
So if my heating system turns on at 12°C (54°F) outdoor temperature, my flow temperature should logically start somewhere around 22°C–25°C (72°F–77°F). Accordingly, at only 5°C (41°F) outside, it should be around 27°C (81°F), and at 0°C (32°F) close to 30°C (86°F).
The system design usually takes the location and outdoor temperature down to about –12°C (10°F). If at 0°C (32°F) flow temperature is already 30°C (86°F) according to my logic, then at –12°C (10°F) the flow temperature should be about 40°C (104°F). But most underfloor heating designs for heat pumps are based on a maximum flow temperature of 35°C (95°F).
Of course, the insulation of the house and the indoor temperatures still play a role. Or is the increase in flow temperature actually so gradual that it only rises by about 0.5–1°C (1–2°F) for outdoor temperature drops in 0–5°C (0–9°F) increments?
A
Alessandro8 Nov 2021 08:25But then the other rooms will get too warm ;-)
Then the throttle is your friend 😉
At the moment, I’m running it at 0.25 with the foot point raised to 20.5cm (8 inches) quite well. The heat pump has been running continuously since yesterday evening with outside temperatures between 5 and 7°C (41 and 45°F). My Golf uses surprisingly much more electricity than the heat pump.
I’ll keep it running like this until my door to the living-dining area is finally installed. After that, everything will change again – right now it’s already getting a bit too warm. But a lot of heat is also escaping into the hallway and stairwell.
At the moment, I’m running it at 0.25 with the foot point raised to 20.5cm (8 inches) quite well. The heat pump has been running continuously since yesterday evening with outside temperatures between 5 and 7°C (41 and 45°F). My Golf uses surprisingly much more electricity than the heat pump.
I’ll keep it running like this until my door to the living-dining area is finally installed. After that, everything will change again – right now it’s already getting a bit too warm. But a lot of heat is also escaping into the hallway and stairwell.
A
Alessandro8 Nov 2021 08:54However, the throttle reduces the total flow rate, which in turn causes cycling.
Providing more than 3L/min (0.8 gallons per minute) to the bathroom and guest WC makes no sense at all.
3L/min (0.8 gallons per minute) is actually already a planning mistake...
Providing more than 3L/min (0.8 gallons per minute) to the bathroom and guest WC makes no sense at all.
3L/min (0.8 gallons per minute) is actually already a planning mistake...
An electric supplementary heater in the bathroom would be a practical solution. It can also be timer-controlled (if you have a consistent daily routine). Or even controlled by a presence detector. In that case, I would not use a standard towel radiator but rather a halogen or ceramic heat lamp. Unfortunately, these are not really available in attractive designs, but you have to make compromises.
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