ᐅ Electricity Consumption of Air-to-Water Heat Pumps

Created on: 20 Nov 2018 16:31
A
Albbino
Hello.

My electricity consumption for my heat pump seems quite high. I have already contacted various professionals: architect, heating engineer, energy consultant, structural engineer, but I can’t shake the feeling that none of them really know what’s going on.

I can give you some key data; I know it’s difficult to make a general statement. But there should be at least an approximate benchmark.

First, about the electricity consumption itself. Last year it was 10,000 kWh (10,000 kWh) for heating and hot water. In the years before, it was between 7,000 and 9,000 kWh (7,000 and 9,000 kWh).

- Our house has heated living space of 180 m² (1,940 sq ft).
- We live at 900 meters (2,953 ft) above sea level, which is quite a cold location, although last winter wasn’t as cold as previous years.
- We have an air-to-water heat pump from Weißhaupt rated at 9 kW.
- The whole house has underfloor heating.
- In the bathroom, there are two additional infrared heaters because the underfloor area was not sufficient. They run for about 1 hour per day in winter—30 minutes in the morning and 30 minutes in the evening.
- Household of 6 people.

The energy certificate states:

Final energy demand 33 kWh/m²a (10.5 Btu/ft²·year)
Primary energy demand 70 kWh/m²a (22.5 Btu/ft²·year)

The certificate is based on a building usage area of 222 m² (2,390 sq ft).

I’m not sure what other information might be needed. Just ask if anything is missing. The electricity consumption just seems very high to me.
blackm8821 Nov 2018 07:26
@HilfeHilfe At altitudes starting from 900 meters (2953 feet) above sea level, it is always difficult to rely on other experiences. Our design based on the average annual temperature is so precise that there is hardly any funding available. The deviation from the normal yearly average temperature is simply too large.
H
HilfeHilfe
21 Nov 2018 07:27
Oh sorry, yes, I missed that. We are located at 116 m (380 ft) above sea level.
R
readytorumble
21 Nov 2018 08:31
If heating were done solely with the electric heating element, the electricity costs would be significantly higher.

Therefore, it should be considered at which temperature the heating element is activated. At altitudes above 900 meters (approximately 3,000 feet), it is likely quite cold, so operating without the heating element might not be possible.

We are located at 530 meters (1,740 feet) above sea level, and here the electric heating elements of the air-to-water heat pump are active for several weeks each year (fortunately, we have a geothermal heat pump) because temperatures of -10°C (14°F) and below are not uncommon.
tomtom7921 Nov 2018 08:48
Hello, we only live 500 meters (about 0.3 miles) apart, but this consumption is too high. We have significantly less with a larger heated area and KfW 70 standard.

You should definitely read up on how to operate your heat pump.

How large is your buffer tank and what type do you have?

First basic tip: set the domestic hot water to a maximum of 45°C (113°F).

Turn the room thermostats fully up and lower the temperatures on the heat pump so that you reach 22°C (72°F) inside the house.

Set a time block for the hot water so that it is only heated during the day, between 9 a.m. and 5 p.m.

I think there are more tips to come.

Some even recommend setting heating lockout times at night, but this does not mean night setback, which is rather counterproductive.
A
Albbino
21 Nov 2018 21:11
I have turned down the hot water.
Thanks for the tips. I will definitely read up on this.
But somehow I don’t think this accounts for most of the extra consumption. If I save 1000 kWh through the tips, that would definitely be a lot.
What do you think?

Somehow I have the feeling that the heating system is faulty.
H
hanse987
21 Nov 2018 22:52
What are the system temperatures of the heating system, meaning the supply and return temperatures? What is the pipe spacing of the underfloor heating?