ᐅ Air-to-Water Heat Pump: Current Consumption and Data

tomtom79 schrieb:

I think there’s still room for improvement with a hydraulic balancing in your case.

Okay, thanks. Your data suggests that construction moisture might still have an effect in my case, or that the monolithic solid construction actually has a few more weaknesses than expected. Let’s see how the second winter goes.

The hydraulic balancing has been done, but of course it could still be improved. A performance factor of 4.2 would probably not be achievable with energy recovery ventilators (ERVs) and without the balancing when using an air-to-water heat pump.

Sorry, forgot to mention... it is a KFW55 house. Electricity consumption is measured with a separate meter, while the heat quantities come from the heating system.

Oetzberger schrieb:

Ok thanks, your data suggests that construction moisture might still have had an effect in my case, or the monolithic solid construction method might have a few more weaknesses than calculated. Let's see how the second winter turns out.

The hydraulic balancing has been done, but of course, it could still be improved. A performance factor of 4.2 would probably not be achievable with an air-to-water heat pump without hydraulic balancing and energy recovery ventilators (ERVs).

With a modulating heat pump, this value of 4.2 is definitely achievable. Unfortunately, we have an on/off heat pump. And it’s already a few years old.

I also think that construction moisture still plays a role for you. What settings do you have?

Domestic hot water

Heating curve, etc.?

The winter was simply cold and long...

tomtom79 schrieb:

With a modulating system, a value of 4.2 is easily achievable. Unfortunately, we have an on/off heat pump, and it’s already a few years old.

I also think that the building's moisture content still plays a role in your case. What settings do you have?

Domestic hot water

Heating curve, etc.?

Well, the biggest efficiency killer for me is a poorly heat-conductive 3-layer parquet flooring, which is probably why I have the heating curve set about one degree higher than would otherwise be necessary. Currently, the heating curve in AIT notation with return flow control is 23.5/22.5/0, which means 22.5°C (72.5°F) return flow at +20°C (68°F) outdoor temperature, and about 26°C (79°F) target return flow at -20°C (-4°F) outdoor temperature. In the deepest winter, I might even have to raise the target return flow to 26.5 or 27°C (79.7 or 80.6°F). The house is located in a small cold-air basin, meaning it is always 1–2°C (2–4°F) colder in the early morning than just a few hundred meters away — that’s why the heating curve shouldn’t be too steep. Otherwise, the heat pump would always run at full capacity at the coldest time in the early morning. I’m still considering a slight daytime heating boost, but since I don’t have photovoltaic panels, I haven’t set that up yet.

Other settings for the modulating air-to-water heat pump from Alpha Innotec: heating hysteresis 1.0K, domestic hot water target 46°C (115°F), domestic hot water hysteresis 3.0K, domestic hot water enabled only from 12:30 to 23:00 (to avoid heating domestic hot water during the coldest early morning hours after showering).

The screenshot shows the consumption values from the heat pump consumption database, including domestic hot water. You can see that the standby consumption during the summer months slightly lowers the seasonal performance factor.

Besides better balancing the heating circuit flow rates through hydraulic balancing, what else could be optimized?

The heating system is my model train substitute 🙂

Oetzberger schrieb:

Otherwise, the heat pump would always run at full power early in the morning when it’s coldest.

Can you set an AT damping?
For exactly that reason, I’m currently testing a 24-hour average temperature.
Combined with a slight daytime increase and a storage heater, it looks like I can largely avoid heating during the night.
At least so far, with the current temperatures.