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

halmi schrieb:

Just checked, in November it was 391 kWh, so about 13 kWh per day for the entire system. Room temperature 22–23°C (72–73°F), KWF55, 218 m² (2344 sq ft) heated area.

For me, it was 373 kWh electricity with 1727 kWh heat output (COP 4.6). We have relatively similar houses and—as far as I remember—the same heat pump. So it’s always a good comparison.

I am quite relieved to see that with 1796 kWh (1796 kWh) of heat from 413 kWh (413 kWh) of electricity, I am more or less within a reasonable range. The first full month living in the house, and it was pretty cold too.

It’s quite surprising to see 1000 kWh (1000 kWh) of electricity consumption in just one month. Even more surprising is seeing in black and white that driving the car around a bit uses almost as much energy as keeping a house comfortably warm for the entire month.

So, November is over. Consumption was 342 kWh including hot water.
128 m² (1,376 sq ft) plus basement (basement unheated).
Average outdoor temperature in November was 5°C (41°F).
Bathroom 22.5°C (72.5°F), all other rooms 21–22°C (70–72°F).

With my settings—overloading the buffer by 5K, active mixing valve (heating curve 5K below the heating curve for buffer charging)—I get about 700 kWh for November (200 m² (2153 ft²), designed according to the energy saving ordinance).

Temperatures are 22°C (72°F), bathroom 23.5°C (74°F).
Operating times average about 3 hours with active demand-controlled ventilation (ERV).

Using the mixing valve, I found out (because I can precisely determine the supply temperature here) what heating curve the house needs, which is exactly 33°C (91°F) at NAT.

Heating curves were (return temperature):

Heat pump:
27°C (81°F) at 18°C (64°F)
32°C (90°F) at 0°C (32°F)
35°C (95°F) at -15°C (5°F)

Mixing valve:
22°C (72°F) at 18°C (64°F)
27°C (81°F) at 0°C (32°F)
30°C (86°F) at -15°C (5°F)

Hysteresis (heat pump):
5K at 18°C (64°F)
4K at -15°C (5°F)

Since the buffer construction (or the buffer itself) causes a temperature difference (delta T) of about 2K between heat pump supply and underfloor heating supply, I have now tried lowering the heat pump heating curve by 3K and reducing the hysteresis to 2K with the ERV open (here the heat pump flow rate equals the underfloor heating flow rate).

On the ground floor, the temperatures are exactly as I want them.
However, in the bathroom and guest room, they have each dropped to 21°C (70°F).

I don’t understand why. Do I have a misconception?

Oh, I forgot to mention that the energy standard is the Energy Saving Ordinance 2016.

November energy consumption: 300 kWh electricity including hot water. However, this does not include control systems and circulation pump, so possibly an additional 15 kWh.
Single-family house approximately 140 m² (1,507 sq ft) plus 73 m² (786 sq ft) basement, currently unheated but within the thermal envelope.
Not built to KfW standard, insulation values slightly better than the Energy Saving Ordinance (EnEV).