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?
netuser schrieb:
If I were you, I would consider that Apple might actually be right Is the Apple Watch also mounted on the north side of the house wall? 😀
Thanks for the tip. I didn’t know that before. At the moment, I’m satisfied with the indoor temperatures, as the interaction between measurement, electronics, and hydraulics seems to be working. So, for now, it’s actually "irrelevant" what the device on the facade is measuring?
Parallel shift should be the setpoint in the Sensocomfort when room control is deactivated. The standard is 20°C (68°F), and I increased it to 21°C (70°F).
Defrosting is estimated via the smart meter. Whenever I observe defrosting outside, I see a drop in power consumption followed by a peak when it overcompensates for the cooled return temperature.
The base power consumption of my house is just under 2 kW at these temperatures. Of that, 1.2–1.5 kW is the heat pump, and 250 W are other devices. So I’d guess about 400 W is for the preheater coil of the ventilation system.
Edit: please don’t check the math in detail. Just a rough estimate 😉
Edit2: according to the smart meter, at night every 50–55 minutes.
Parallel shift should be the setpoint in the Sensocomfort when room control is deactivated. The standard is 20°C (68°F), and I increased it to 21°C (70°F).
Defrosting is estimated via the smart meter. Whenever I observe defrosting outside, I see a drop in power consumption followed by a peak when it overcompensates for the cooled return temperature.
The base power consumption of my house is just under 2 kW at these temperatures. Of that, 1.2–1.5 kW is the heat pump, and 250 W are other devices. So I’d guess about 400 W is for the preheater coil of the ventilation system.
Edit: please don’t check the math in detail. Just a rough estimate 😉
Edit2: according to the smart meter, at night every 50–55 minutes.
driver55 schrieb:
Is the Apple Watch also hanging on the north side of the house? 😀No, but the heating temperature sensor is 🙂
Even though it’s on the north side, it initially showed quite (too) high temperatures. Now it’s accurate 🙂
OWLer schrieb:
Thanks for the tip. I didn’t know that. At the moment, I’m happy with the indoor temperatures and it seems like the interaction between the measurement, electronics, and hydraulics is working. So basically, does it even matter what the device on the facade measures?Basically, it probably doesn’t matter, but it can’t hurt to set it correctly, right? 😉
We have the Sensocomfort installed next to the front door as well, so you get used to checking the time and temperature there. If the temperature is off (in our case by about 3°C (5.4°F)), it’s not a disaster, but it is annoying.
OWLer schrieb:
The setpoint for “parallel shift” should be in the Sensocomfort when the room sensor control is disabled. The default is 20°C (68°F) and I increased it to 21°C (70°F).Ah, okay. I didn’t understand that as “parallel shift” before. I had set it to 21.5°C (70.7°F) and now to 22°C (71.6°F).
OWLer schrieb:
Defrosting is estimated using the smart meter. Whenever I see defrosting outside, I notice a drop in power consumption followed by a peak when it overcompensates for the cooled return temperature.I’ll have to check that too... Thanks.
Musketier schrieb:
Outside Temperature
Flow Temperature (Setpoint)
20
26
15
27
10
28
5
29
0
30
-5
31
-10
32
-15
33
-20
34
Outside Temperature (Outside Air Temperature)
Flow Temperature (Setpoint)
I am using an offset of +6 and a slope of 0.2 Quite “questionable” values. For warmer outside temperatures, it looks like an older building, while towards colder temperatures it seems more like a new build. 🙄
B
Benutzer20022 Dec 2021 09:41You all have new / insulated houses, right? And then such supply temperatures?
I still live in an older building without external insulation and with outside temperatures currently around -4/-5°C (24.8/23°F) at night, I manage with supply temperatures of 29/30°C (84.2/86°F) (indoor temperature currently 21.5°C (70.7°F)).
I think this is actually due to the system design with very tight pipe spacing. I find that surprising.
Defrosting, by the way, also happens roughly every hour.
I still live in an older building without external insulation and with outside temperatures currently around -4/-5°C (24.8/23°F) at night, I manage with supply temperatures of 29/30°C (84.2/86°F) (indoor temperature currently 21.5°C (70.7°F)).
I think this is actually due to the system design with very tight pipe spacing. I find that surprising.
Defrosting, by the way, also happens roughly every hour.
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