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

Reading this discussion, I’m once again struck by how differently people think (for example, how unusual I am). I can’t recall ever using a thermometer inside the house. For me, the challenge would have been telling the installer which temperature I want in each room. I couldn’t say exactly how warm it is here, but it feels just right.

From my time renting, I clearly remember how dramatically subjective the idea of a comfortable temperature can be. One person in the house argued with the heat metering company because their consumption was almost twice that of the rest of us. It turned out they had a much higher usage especially in the bathroom. When I visited, it became clear — it was warm inside the apartment, and when they opened the bathroom door, a blast of heat came out.

I believe that in all the calculations, there is great (energy-saving) potential in individual heating behavior, which can vary significantly but is often seen as “normal” and “necessary” by everyone.

It’s probably similar with water, electricity, and the frequently discussed fuel consumption of cars. A few unnecessary trips less, or a bit more discipline, and the difference between consuming 7.4 liters or 8.0 liters per 100 km becomes irrelevant.

Alessandro schrieb:

I’d like to join the conversation here.
Here are the details:
200 sqm (2150 sq ft) house.
Modulating 8 kW air-to-water heat pump with 100 L (26 gallons) buffer tank and mixing pump group.
ERR enabled.

Heating curve:
18°C (64°F) = 25°C (77°F) target return temperature
0°C (32°F) = 30°C (86°F) target return temperature
-15°C (5°F) = 33°C (91°F) target return temperature

Consumption at -2°C (28°F) outdoor temperature over 24 hours was 29 kWh
Average run time per cycle was 5 hours.

Bathroom = 22.8°C (73°F)
Other rooms = 22°C (72°F)

This is quite similar to my situation in terms of temperatures, living area, and consumption. Only the bathroom doesn’t get as warm for me, max 21.5°C (71°F). And I have many faults/errors...

pagoni2020 schrieb:

Reading this discussion, I’m once again reminded of how differently people think (for example, in a very personal way). For instance, I can’t remember ever having used a thermometer inside the house. That would have been a problem for me – telling the installer exactly which temperature I want in each room. I couldn’t say how warm it is in our home, but it feels just right.
From my time renting, I clearly remember how drastically different people’s comfort temperature can be. One person in the house argued with the company reading the radiator meters because their consumption was almost double that of the rest of us. Eventually, it turned out that they used much more energy, especially in the bathroom. On a visit, I realized why: the apartment was warm, and when they opened the bathroom door, a wave of heat came out.
I believe there is great (energy-saving) potential in the very individual heating behavior, which can vary widely, but is considered "normal" and "necessary" by each person involved.
The same certainly applies to water, electricity, and the often-discussed fuel consumption of cars. A few unnecessary trips less, or just a bit more discipline, can eliminate the difference between consuming 7.4 liters or 8.0 liters per 100 km (7.4 or 8.0 liters per 100 kilometers).

You may be right. But I don’t care about saving. It doesn’t matter to me. I just want the heating system to operate without faults, last a long time, and provide good warmth. I only expect efficiency as promised by the manufacturer, minus some correction factor for installation quality.

Financially, I don’t mind paying whether the annual heating costs are 800 or 1500 euros. It just gets lost among all the other payments anyway 🙂

No, I didn’t mean you specifically. It’s just something I’ve noticed in many of the heat pump calculations and especially the comparisons discussed here—often it really comes down to individual behavior. I already mentioned that we currently have a pretty standard gas heating system here, probably rather roughly designed, but the temperatures are okay. The consumption values might not be impressive, but at least the heating system does what it’s supposed to do.

For example, towel warmers here were connected directly to the water system, and no matter how much you turn the controls, the thing stays cold, so it’s mostly just decorative.

Well… it’s just a temporary home now anyway…

It is often said that an increase of 1°C (1.8°F) raises electricity consumption by about 2.5%. In my opinion, this is ridiculously low and negligible.
You really have to be patient when adjusting the settings. I have basically always done it wrong!
The more drastically you change the heat pump’s settings, the longer it takes to adapt.
The so-called steady state is reached after 24-48 hours.
The heat pump detects the flow rate from the pump (which of course varies with active ERR) and modulates accordingly, either down or up depending on demand.
It definitely takes about a day until it runs perfectly.

@Bookstar: I can really only recommend contacting a technical office. They calculate the flow rates based on your desired room temperature, which you can then use for the hydraulic balancing. This way, you can also see the total flow rate of the underfloor heating to properly size the heat pump. You might also need to adjust the compressor performance.

Bookstar schrieb:

The temperatures, living space, and consumption are similar to mine. I just can’t get the bathroom that warm, max 21.5°C (70.7°F). And there are many disruptions...

For me, the values of the heating curve indicate the return temperature. You can add another 5 K (5°C / 9°F) for the supply temperature ;-)