Reduce/optimize the consumption of a ground source heat pump (GSHP)?

Hello,

unfortunately, this question has not yet been answered in the field of heat pumps. Maybe I will have more luck here. Our old hot water boiler of the recently and suddenly broke down. Therefore, last week we installed a new domestic hot water heat pump (DHWHP) with 270 liters (4 persons) (recirculation mode) and connected it to the available hot water circulation. The circulation is quite helpful, as otherwise hot water sometimes takes quite a long time. A mechanical timer was installed; the circulation pump now does not run for 7 hours at night and is also interrupted for 3 hours during the day.

I have some general questions about this, maybe you can give some tips/advice:

1. How can the electricity consumption be reduced as effectively as possible if the DHWHP is connected to the circulation line (which is rather poorly insulated in the house)?

2. According to the energy saving ordinance, the circulation pump must run at least 16 hours daily to keep the pipes free of germs. Is this really that important in practice?

3. What target temperature is generally recommended for the DHWHP itself? Legionella protection at 62°C is performed once a month according to settings.

4. The boiler room where the DHWHP is located has only about 16 m³ volume. 20 m³ is recommended. A forced ventilation (ventilation grille with noticeable fresh air) is present due to the oil heating system. However, the room (normally about 20°C) cools down noticeably by up to 5-6°C (14-15°C) during the longer recirculation operation of the DHWHP. Afterwards, the temperature rises again. Is this still okay or should I lead the exhaust air to the outside to increase the efficiency of the DHWHP?

Many thanks for feedback.

1. How can electricity consumption be reduced as effectively as possible when the BWP is connected to the circulation line (which is rather poorly insulated in the house)?

Run it even less. But then you might as well turn it off completely...

2. According to the energy saving regulations, the circulation pump must run at least 16 hours a day to keep the pipes free of germs. Is this really that important in practice?

As long as you regularly draw water, this is not a problem at all.

3. What set temperature is generally recommended for the BWP itself? The legionella protection with 62°C is carried out once a month according to the settings.

48-50 degrees are sufficient. I would either turn off the legionella program or run it weekly. Once a month is pointless.

4. The boiler room where the BWP is located has only about 16 m³ volume. 20 m³ is recommended. A forced ventilation (ventilation grille with noticeable fresh air) is present because of the oil heating. However, the room (normally about 20°C) cools down noticeably by up to 5-6°C (14-15°C) during the longer recirculation operation of the BWP. After that, the temperature rises again. Is this still okay or should I lead the exhaust air outside to increase the efficiency of the BWP?

Exhaust air is always good. Whether it really increases efficiency? You definitely won’t be able to measure it, as the "improvement" is too small for that.