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 🙂
R
RotorMotor18 Jan 2021 11:53M. Gerd schrieb:
We have now lowered the heating curve by 1, and the consumption has dropped from 30 kWh per day to 20 kWh per day.That doesn’t seem plausible. Has the outdoor temperature also increased?
Was there enough waiting time, about 48 hours?
RotorMotor schrieb:
That doesn't seem plausible.
Has the outdoor temperature increased as well?
Has there been a long enough waiting period? About 48 hours? A typical beginner's mistake. The house is initially 1 degree warm and you save that energy for free at first. Your remark about the 48 hours is correct. After that, the consumption rises.
A
Alessandro18 Jan 2021 14:32I firmly believe there is a mistake.
24°C (75°F) room temperature with a 30°C (86°F) supply temperature, 10cm (4 inches) of underfloor heating pipe, and outdoor temperatures below freezing?
24°C (75°F) room temperature with a 30°C (86°F) supply temperature, 10cm (4 inches) of underfloor heating pipe, and outdoor temperatures below freezing?
T
T_im_Norden18 Jan 2021 15:22We have a room temperature of 23°C (73°F) in the living room, 20–21°C (68–70°F) in the bathrooms and other rooms, and about 18°C (64°F) in the bedroom.
With a calculated supply temperature of 22–23°C (72–73°F) and supply temperature cut-off at 27–28°C (81–82°F) during below-freezing conditions.
So far, I have not had to increase the supply temperature. At the moment, the heating system adjusts this through runtime, which ranges between 14 and 20 hours.
150 m² (1,615 sq ft) under energy saving regulations with slightly improved wall insulation.
With a calculated supply temperature of 22–23°C (72–73°F) and supply temperature cut-off at 27–28°C (81–82°F) during below-freezing conditions.
So far, I have not had to increase the supply temperature. At the moment, the heating system adjusts this through runtime, which ranges between 14 and 20 hours.
150 m² (1,615 sq ft) under energy saving regulations with slightly improved wall insulation.
A
Alessandro18 Jan 2021 15:39Are you sure there is no parallel shift of the heating curve applied?
A
Alessandro18 Jan 2021 15:59I need to increase the flow temperature by about 5°C (9°F) here to reach these temperatures. 😱
So the heating curve you use for the flow, I use it as the required return temperature (RL_soll).
So the heating curve you use for the flow, I use it as the required return temperature (RL_soll).
Similar topics