ᐅ Properly Setting a Heat Pump – Experiences

Hello everyone,

Our heat pump (Weishaupt LS 8-B) has been running for just about 11 months now. We don’t have much experience with the statistics and detailed settings, so I wanted to ask here if anyone can tell us what we might need to change or adjust.

The house is built to KfW 55 standard, 150m² (1,615 sq ft) with underfloor heating and thermostats (all set to maximum). The target room temperature is set to 21°C (70°F), yet every room is slightly warmer (22–23°C / 72–73°F). The heating curve is set to 0.15. The domestic hot water temperature is set to 50°C (122°F), and once a week the system runs a legionella program at 60°C (140°F) for 2 hours.

I should also mention that I don’t have access to the Weishaupt portal, which requires an additional fee, and unfortunately, there is no separate electricity meter for the heat pump.

Compressor running hours: 3115h
Compressor cycles: 2107 (is this too much?)
Defrost cycles: 531
Electric heater 1 running hours: 46h
Electric heater 2 running hours: 4h
Electric heater 1 cycles: 942 (seems very high for the hours run)
Electric heater 2 cycles: 7
Cycles frozen: 2074 (what could this be?)
Thermal energy for heating (11 months): 8409 kWh
Thermal energy for domestic hot water (11 months): 1979 kWh

The heating engineer said everything is set up well, but I would appreciate more objective feedback on some of these values above.

Thanks in advance!

NewHouseAppear schrieb:



Operating hours compressor: 3115h
Compressor cycles: 2107 (too many?)
Defrost cycles: 531
Electric heater 1 operating hours: 46h
Electric heater 2 operating hours: 4h
Electric heater 1 cycles: 942 (seems very high for the number of hours)
Electric heater 2 cycles: 7
Frozen cycles: 2074 (what could this be?)
Thermal energy for heating per year (11 months): 8409 kWh
Thermal energy for hot water per year (11 months): 1979 kWh

The heating technician said everything is well adjusted, but I would appreciate further objective experiences on some of the values above.

Thanks in advance!

The number of cycles also seems very high to me. On average, the compressor switches on about 6-7 times per day. Probably less often in summer.

I don’t have my own statistics on this. My Mitsubishi Geodan mostly runs continuously when turned on by timer or remotely. Maybe 2-4 start-stop cycles per day, mostly when reheating hot water.

Having a flow temperature of 50°C (122°F) and heating up to 60°C (140°F) frequently obviously consumes a lot of electricity. According to the German Environment Agency, legionella prevention programs like these are not sufficient.

For comparison: energy consumption data from a renovated 125m² (1345 sq ft) old building (KfW70 standard) with 4 occupants is about 4700 kWh for heating and 1000 kWh for hot water.

I adjusted the heating curve myself until it felt comfortable. The heating technician had set it too warm before.

NewHouseAppear schrieb:

Thermal energy for heating per year (11 months): 8409 kWh
Thermal energy for hot water per year (11 months): 1979 kWh

What does thermal energy mean? Is that your electricity consumption? That can’t be right. So how high is your electricity consumption (grid supply)?

Buchsbaum schrieb:

What does thermal energy mean? Is that your electricity consumption? That can’t be. So what is your actual electricity consumption (grid supply)?

Thermal energy is the heat output of the heating system, not the electricity consumption.
@galdreth: Are the data referring to the electricity consumption or the thermal output? Honestly, I don’t really know what you can adjust on the Weishaupt unit besides the target room temperature and the heating curve.

The values represent the thermal output. Electricity consumption is approximately 1300 kWh.

We keep the temperature consistently at 20°C (68°F) everywhere, including the bathroom, with fluctuations of about ±1°C (±2°F). Is it perhaps set warmer in your homes?

Another factor might be ventilation: we have a ventilation system with heat recovery installed here.