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?
This morning, the heating system measured an outside temperature of -4.5°C (23.9°F) (Apple claims -6°C (21.2°F)) and is sending 30°C (86°F) into the supply line.
The unit was nicely frozen over.
I’m wondering what temperature I should set the bivalence point to. The default was something strange, like -7°C (19.4°F) or so. I have now set it to NAT.
The unit was nicely frozen over.
I’m wondering what temperature I should set the bivalence point to. The default was something strange, like -7°C (19.4°F) or so. I have now set it to NAT.
OWLer schrieb:
This morning, the heating system measured an outside temperature of -4.5°C (23.9°F) (Apple claims -6°C (21.2°F)) and the supply temperature is set to 30°C (86°F).
The unit is nicely frozen over.
I’m wondering what temperature I should set for the bivalence point. The default was something strange, like -7°C (19.4°F) or so. I’ve set it to NAT for now. What heating curve are you currently using? Any offset?
OWLer schrieb:
I'm wondering what temperature to set the bivalence point to. The default was something strange, like -7°C (19°F) or so. I changed it to NAT. I would say it depends on how the system is designed.
If the maximum output of the heat pump is sufficient for NAT, there is no reason to set the bivalence point higher, right? Or do you even have some reserves?
I assume the second system is the electric backup heater. That's always less efficient than the heat pump.
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