ᐅ Heat pump/ventilation system with excessive energy consumption

Hello forum,

My brother-in-law sent me a screenshot from his photovoltaic app. The values shown there seem illogical and much too high to me. As far as I can interpret, his photovoltaic system generated 38 kWh and additionally drew 12 kWh from the grid. That adds up to 50 kWh for the day. He has a KfW40 house built in 2022, with a Tecalor THZ 504 heat pump/ventilation system. He also uses this system to cool his house.

The total seems far too high to me, but I have no personal experience with a heat pump/ventilation system. I have now asked him to document the electricity consumption on the meter every evening to see if he really consumes what the app shows. I once had my energy flow meter for my photovoltaic system connected incorrectly, so it showed my generated energy as consumption.

In recent days, we had warm/hot weather. During the day, when the cooling runs, the photovoltaic system supplies electricity. In the evening, when the sun is gone, there is no more power from the photovoltaic system, but then cooling should no longer be necessary.

Do you have any experience with such systems?

I had a similar consumption. However, I charged my electric car.

Since the device has a power consumption of 1.4 kW when cooling – which means a maximum of 34 kWh per day – something is clearly going wrong...

The controlled residential ventilation system definitely cannot consume 50 kWh per day.

An electric car can use that much, and maybe a poorly adjusted heat pump in winter as well.

Normally, the controlled residential ventilation system uses about 1-2 kWh per day. I measured it at my place once and it was around 1.5 kWh.

I see it the same way. However, there is no electric car, just a small pool with its own heat pump. But that is also scheduled, so we can skip the 3-4 kWh/day, assuming the pool even needs that much.

Coxiella schrieb:

Normally, a mechanical ventilation system with heat recovery uses about 1-2 kWh per day; I measured mine once, and it was around 1.5 kWh…

In this case, the Tecalor system is not just a simple mechanical ventilation with heat recovery. It can actively cool (I believe it even has its own cooling circuit) and consumes energy accordingly. So, this is per hour, not per day.

nordanney schrieb:

In this case, the Tecalor is not just a standard mechanical ventilation system with heat recovery. It can actively cool (I believe even with its own cooling circuit) and handles

per hour. Not per day.

If we assume 10 hours per day when cooling is needed, that results in 14 kWh, and this period exactly coincides with daylight hours (photovoltaic panels provide electricity). He only has a 6 kWh battery, with 5 kWh effectively usable. But at least in summer, he should manage from sunset to sunrise. If we assume a base load of 10 kWh for three people and an additional 15 kWh for the heat pump, then 25 kWh per day is too much energy consumed.