Hello everyone,
We have an 8 kW air-to-water heat pump from Kermi and a KfW55 house with about 200m² (2,150 sq ft). Currently, the indoor temperature is quite warm at 24.5°C (76°F). Yes, I know that is quite high. The consumption figures are only for the underfloor heating and are separate from the hot water usage.
I understand that the higher temperature leads to increased consumption, but could it possibly be too high?
We live just north of Hanau and in December maintained around 23°C (73°F) with a daily consumption of 6-8 kWh. When it got colder around Christmas, consumption rose to about 20 kWh. It has gotten even colder recently (-6 to 2°C / 21 to 36°F), and we simultaneously raised the temperature to about 24°C (75°F), resulting in a consumption of 30 kWh now.
I read that average consumption is based on 19°C (66°F), and for every degree above that, you need roughly 10% more energy. That would put us at about 60% higher consumption, but is 30 kWh then reasonable? According to the KfW application, we require around 30 W/m² (3 W/sq ft), which totals about 6 kW. But what exactly does that 6 kW refer to — over 24 hours? At what outside temperature? With an indoor temperature of 19°C (66°F)?
We had days in December with consumption as low as 6 kWh, which I think is quite good. However, with a few degrees colder weather and the heating curve increased by 1°C (2°F), the consumption jumps so much? By the way, we heat only via the heating curve, without any additional controllers.
Thanks in advance 🙂
We have an 8 kW air-to-water heat pump from Kermi and a KfW55 house with about 200m² (2,150 sq ft). Currently, the indoor temperature is quite warm at 24.5°C (76°F). Yes, I know that is quite high. The consumption figures are only for the underfloor heating and are separate from the hot water usage.
I understand that the higher temperature leads to increased consumption, but could it possibly be too high?
We live just north of Hanau and in December maintained around 23°C (73°F) with a daily consumption of 6-8 kWh. When it got colder around Christmas, consumption rose to about 20 kWh. It has gotten even colder recently (-6 to 2°C / 21 to 36°F), and we simultaneously raised the temperature to about 24°C (75°F), resulting in a consumption of 30 kWh now.
I read that average consumption is based on 19°C (66°F), and for every degree above that, you need roughly 10% more energy. That would put us at about 60% higher consumption, but is 30 kWh then reasonable? According to the KfW application, we require around 30 W/m² (3 W/sq ft), which totals about 6 kW. But what exactly does that 6 kW refer to — over 24 hours? At what outside temperature? With an indoor temperature of 19°C (66°F)?
We had days in December with consumption as low as 6 kWh, which I think is quite good. However, with a few degrees colder weather and the heating curve increased by 1°C (2°F), the consumption jumps so much? By the way, we heat only via the heating curve, without any additional controllers.
Thanks in advance 🙂
T
T_im_Norden18 Jan 2021 16:05If you meant me, no, we do not have any lateral displacement.
T_im_Norden schrieb:
With a calculated supply temperature of 22/23°C (72/73°F) and a supply shut-off temperature of 27/28°C (81/82°F) and outdoor temperatures below freezing.Honestly, I don’t really understand this sentence. I’m not familiar with these terms. What exactly is the calculated supply temperature and what does supply shut-off mean? With a supply temperature of 22/23°C (72/73°F), you can’t heat a living room to 23°C (73°F). Depending on the temperature difference, the average floor heating temperature would still be lower. That’s basically cooling :-P I think I’m missing something...
Alessandro schrieb:
I have to increase the supply temperature by about 5°C (9°F) to reach these temperatures. 😱
So the heating curve you use for the supply line, I use as my return temperature setpointWe have just accepted that it doesn’t make sense to keep the bathroom at 23-24°C (73-75°F) all day 😉
T
T_im_Norden18 Jan 2021 16:44This is determined by the heating curve.
My condensing boiler calculates a flow temperature based on the set heating curve. This is the target flow temperature, for example, 22°C (72°F).
Then I have the hysteresis, which is the flow temperature at which the heating turns off and remains off until the target flow temperature is undershot.
At the moment, this happens with a 5 K (5°C / 9°F) difference, so here at 27°C (81°F).
Therefore, I do not have a fixed flow temperature that stays constant all the time; instead, it gradually increases.
My condensing boiler calculates a flow temperature based on the set heating curve. This is the target flow temperature, for example, 22°C (72°F).
Then I have the hysteresis, which is the flow temperature at which the heating turns off and remains off until the target flow temperature is undershot.
At the moment, this happens with a 5 K (5°C / 9°F) difference, so here at 27°C (81°F).
Therefore, I do not have a fixed flow temperature that stays constant all the time; instead, it gradually increases.
H
HilfeHilfe19 Jan 2021 06:00M. Gerd schrieb:
How could he not notice water damage?
We have now lowered the heating curve by 1, and consumption has decreased from 30 kWh per day to 20 kWh per day. Back then, consumption increased from 20 kWh to 30 kWh, and I couldn’t quite believe that a difference of just one degree was responsible, but apparently that is the case.Tenant who has not yet recorded consumption values. Water in the toilet was leaking slightly but made a significant difference over 8 months. I think about 400 euros.
A
Alessandro19 Jan 2021 07:55Very interesting, thanks for the explanation :-)
I can also adjust the fan speed on my heat pump. Can you do that as well? What settings or values do you use for this?
I can also adjust the fan speed on my heat pump. Can you do that as well? What settings or values do you use for this?
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