ᐅ Ground Source Heat Pump for a 200 m² Single-Family Home with Underfloor Heating, KfW55 Standard – Settings and Optimization

halmi schrieb:

Just two adults lying in bed produce about 400 watts,

Maybe for 25 minutes 😎, but otherwise the average person is around 120 watts (awake/during the day). In a resting state it’s about 80 watts. Under the blanket at night it’s the same, but thanks to ceiling insulation, even less heat actually reaches the room.

halmi schrieb:

I can’t quite understand how those temperature values are reached inside the house. Yesterday, both floor-to-ceiling windows in the bedroom were left tilted open by mistake, and we still had "only" 19°C (66°F) in the bedroom. Just two adults lying in bed produce around 400 watts, which should noticeably raise the temperature in any new build after 6-8 hours.

The ventilation system alone already stabilizes the temperature relatively well inside the house, or don’t you have one?

Which values are you referring to? For me, before airing it’s around 20°C (68°F) and after airing between 18.5°C and 19.5°C (65°F and 67°F), depending on the duration and outside temperature. I also don’t quite get how you can end up with 16°C (61°F) during airing. At near zero degrees outside, I would probably have to leave it open for half a day.

By the way, I’m also calming down a bit right now. I recalculated more precisely and now come to almost 5 as the COP for all heating consumers including distribution in the house. And we probably still haven’t reached average winter temperatures yet. The compressor now consumes about 10 kWh/day, but then the other consumers weigh less. However, it could well be that after the winter I end up somewhere around 4.5.

Sorry, I meant the values from @Alessandro

grericht schrieb:

Including electricity for the heating pump and the heat pump control? Your numbers are similar to mine. But I just read that the distribution through the heating system also needs to be considered. For me, that's about an additional 35W for the heating pump (which runs during subzero temperatures), 25W standby for the heat pump, ERR+-valves, and the other pumps + heating pump running while heating draw even 255W. This means I have at least 25W running continuously, the heating pump at 35W runs about 15% of the time at ambient temperatures above 5°C (41°F) and 100% below 5°C (41°F), and about 6 hours per day the 255W load is added. Roughly, this amounts to around 2kWh on heating days (probably more), 0.7kWh on summer days, and about 1–1.5kWh in passive cooling mode. This naturally lowers the COP significantly, especially for hot water.

We have a Viessmann compact unit. It includes hot water and all kinds of pumps inside. Around it, we have nothing—no buffer tank, no additional pump, no circulation, nothing. ERR valves are normally open without power, so they also don't consume electricity. Since we don’t have a separate heat pump meter, our COP values come from the Viessmann heat pump itself. Because everything is integrated there, I sincerely hope that pump electricity and similar loads are included. Of course, I cannot say exactly how accurate these figures are.
Based on the total consumption (which I get from the photovoltaic portal), I estimate a base load of about 150kWh per month, plus around 25kWh each for hot water and ventilation. When the heating is on, monthly consumption increases by about 100kWh during transitional seasons—and naturally more during harsh subzero temperatures. Overall, this year we expect about 1,800–2,000kWh of heating electricity for 170m² (about 1,830ft²) and two people, plus 300kWh for hot water (including all pumps)... No idea if that’s a lot.

Hangman schrieb:

We have a Viessmann compact unit. It includes domestic hot water and various pumps all integrated. Outside of that, we have nothing else—no buffer tank, no additional pump, no circulation, nothing. The ERR valves are electrically open without power, so they don't consume electricity. Since we don’t have a separate heat pump meter, our COP values come directly from the Viessmann heat pump itself. And because everything is integrated there, I hope the pump electricity consumption and so on are included. I don’t know exactly how accurate these values are.

Based on the total consumption (which I get from the photovoltaic portal), I assume we have about 150 kWh base load per month plus about 25 kWh each for hot water and ventilation. Once the heating is on, the monthly consumption increases by around 100 kWh during the transition periods—of course, more during severe subzero temperatures. In total, this year we expect about 1,800–2,000 kWh heating electricity plus 300 kWh for hot water (including all pumps) for 170 sqm (about 1,830 sq ft) and two people... no idea if that’s much.

My heat pump "measures" not only the heating and hot water heat output but also the “environmental energy.” I assume this is an estimate based on the device having a certain COP, and it then calculates the environmental energy “extracted” from the produced heat amount. I believe these are purely estimated values, and I think your system is similar. I wouldn’t expect your unit to have an electricity consumption meter. Although, for you, it would be quite easy to add a consumption meter and then determine the actual seasonal performance factor (SPF).

For comparison, I hope and think that for 5 people in 200 sqm (about 2,150 sq ft) with 2 bathrooms, we will use around 2,000 kWh over a year including ventilation. It will be interesting to see.

Two questions remain unanswered, and I would be very grateful if someone could address them:

• Do you know or can you guess how the heat pump determines the heat produced? Are these estimates or measurements? If measurements, are they calibrated and reliable or just approximate as a reference? If not calibrated and reliable: how is the seasonal performance factor calculated then, since the produced heat amount is essential for that?!
• Does it make sense to not heat completely unused rooms? This concerns individual unused rooms in the basement—not leaving the entire basement cold—and also the bedroom, which ideally should stay as cool as possible.