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.
A
Albbino
21 Nov 2018 23:42
Flow temperature 30.4°C (87°F)
Return temperature 27.3°C (81°F)
I have attached some pictures showing the spacing.

Unterbodenheizung: Rohrschlangen im Rohbau, blaue Sockelleiste, Fenster im Hintergrund.


Fußbodenheizung: Verlegte Rohre in einem unfertigen Raum mit Fenstern.


Fußbodenheizung: spiralförmige Heizrohre auf Dämmplatten verlegt, Baufortschritt sichtbar.


Unterbodenheizung: Serpentinenschleifen auf Schluter-Ditra-Unterlage im Badezimmer.
A
Albbino
24 Nov 2018 09:26
And now? Good or not?
berny24 Nov 2018 10:21
At first glance, that looks quite decent. Somewhere your house seems to be losing too much heat; maybe a ventilation system is pulling all the warmth out? Have you checked for thermal bridges? Six people also require a considerable amount of energy for hot water preparation, which can become quite costly depending on showering and bathing habits. How much (cold) water do you use per day/week/month? That can give a rough idea, even if you don’t have a heat meter for hot water.
A
Albbino
24 Nov 2018 10:45
We don’t have any ventilation.
Thermal bridges. I would need a thermal imaging camera for that.

The two youngest just get bathed every now and then.
berny24 Nov 2018 10:54
You can also buy a laser infrared thermometer for about 50 euros and, when it’s below freezing outside, walk around the house with it to check critical points such as window and door connections, seals, patio or platform junctions with the house, and so on. No matter how inaccurate such a device might be, it will still show you trends. Is it noticeably warmer somewhere compared to the outer wall? The same applies to the attic, if there is one. Is any heat “creeping” out of the house there? But as mentioned before, the hot water demand for six people should not be underestimated.
A
Albbino
24 Nov 2018 12:11
There is no attic.
I can borrow a thermal imaging camera from our company.
Let's see what I discover.