ᐅ Vitocal 300 A – in use for over a year now. I have a few questions...

Hello everyone,

I have been living in our KfW 70 house since September 2014 and now have a few questions about heating.

I have a Vitocal 300 air-to-water heat pump installed indoors in the basement.

There is also a 200L (53 gallons) hot water tank connected.

The underfloor heating covers about 130m² (1400 ft²).

The room temperature is set to 21 degrees Celsius (70°F). So far, there has been no night setback.

The heating curve settings are: slope 0.4 – level 0K.

The seasonal performance factor displayed is 4.3.

The domestic hot water temperature is 55 degrees Celsius (131°F).

During this period, I have used about 5000 kWh of electricity – which seems quite high to me.

Additionally, the compressor has already run for 3800 hours and has cycled 1800 times. Assuming a lifetime of 40,000 hours, that would amount to just about 10 years.

Is this normal? The electricity consumption and compressor operating hours seem relatively high to me.

Unfortunately, I am a complete beginner when it comes to heating and have relied entirely on my heating technician. Hopefully, I can find some answers here.

I was told it might be normal to heat more in the first year because the house is not fully dried yet (brick construction).

Thanks and best regards

Hot water production via heat pump will be the critical point. Can you not lower the hot water temperature to about 42°C (108°F), since shower water really doesn’t need to be any warmer? That would certainly save a significant amount of energy. Depending on the size of the hot water tank, there should not be stagnant periods that would raise concerns about Legionella bacteria. Some heat pumps also have a Legionella protection switch, which periodically heats the water briefly to 60°C (140°F).

Hello,

thank you for the reply. The day before yesterday, I lowered the water temperature from 60°C (140°F) to 45°C (113°F). Maybe that will help.

What is the exact time period for the consumption? 2014 could also mean 2 years, but in any case, you are already in the second heating season. Then the value might be acceptable. Did the heat pump also heat the screed?

1900 hours per year is fine, and the number of starts as well, meaning it seems the system is not cycling excessively.

As far as I am informed, the following applies to domestic hot water:
Hot water storage tanks should always produce water at 60 degrees Celsius (140 degrees Fahrenheit). This ensures reliable protection against infections. If the temperature is lower, dangerous Legionella bacteria can multiply.

Source: Test .de

RFR schrieb:
As far as I know, the requirement for hot water storage is:
Hot water tanks should always produce water at 60 degrees Celsius (140°F). This ensures reliable protection against infections. If the temperature is lower, dangerous Legionella bacteria can multiply.
Source: Test .de

I don’t think that is the best source when it comes to technical expertise on this topic.
Aside from that, it depends on the type of storage tank (e.g., with heat exchanger/fresh water station or without) and also the size of the tank (how often the water is replaced). Often, the risk from a shower that hasn’t been used for a long time is much greater in terms of inhaling Legionella. Drinking or eating is comparatively quite safe.