ᐅ New heat pump to replace oil heating with existing radiators

Have I already mentioned that I have an 8 kWp photovoltaic system on the roof with a 5 kW battery storage? But you are probably right, and I will continue looking for another solution. However, I’m hesitant to replace more than 15 radiators. There simply isn’t enough space in some rooms. Besides, the house isn’t that old. The windows, insulation, everything is still in excellent condition... As I said, it’s a prefabricated house with factory-made walls.

strzata schrieb:

Did I mention that I have an 8 kWp photovoltaic system on the roof with a 5 kW storage battery?

No, but that doesn’t really affect the heating or help you much during winter. With my 10 kWp system, I produced less than 1,000 kWh from November to the end of February. During that time, the heating runs at full capacity.

strzata schrieb:

I’m reluctant to replace more than 15 radiators. Some rooms simply don’t have space. And the house isn’t that old. The windows and insulation are still in great condition...

1. You have to choose one of two options: either pay once for new radiators or pay high costs for the next 20 years...
2. Lack of space? I find that hard to believe. A 33 cm (13 inch) radiator is only deeper; height and length remain the same.
3. Everything still in great condition? Maybe nothing is broken, but “great” in terms of good insulation, definitely not. Otherwise, you wouldn’t need 6,000 liters (1,585 gallons) of heating oil per year. A new 330 m² (3,552 sq ft) house doesn’t require €5,500 in oil costs. It only needs around €800 in electricity. Just saying...

A different question. In my newly built house from 1990, I also used oil heating. For about 280sqm (3000 sq ft) spread across 2-3 apartments, I don’t recall using anywhere near 6000 liters (1585 gallons) of oil.

strzata schrieb:



This is what’s in the counteroffer. I can’t interpret the dummy data.

Not 60,000 kWh, but 6,000 liters of oil consumption.

Because with the heat pump the supply temperature is only 45 to 50 degrees, and with oil I sometimes had almost 60 degrees.

The picture shows that below -7°C (19°F) the electric heating rod has to provide additional heating. In your area, the NAT (lowest ambient temperature) might be around -13°C (9°F), so there will still be quite a bit of time when the coefficient of performance (COP) is only about 1.0, which is quite inefficient.

One liter of oil provides about 10 kWh of heating energy, assuming the burner doesn’t lose any heat through the chimney.

The logic behind combining radiators with air conditioning is a bit weak: If the outdoor unit delivers a maximum of 15 kW, the air circulators in the air conditioning units cannot add more heat output to the rooms. The total supplied heat must be shared between radiators and air conditioning units, so there will actually be less heat available for the radiators than if they worked alone. It would be different if you added a separate air conditioner alongside the heat pump: then you would have two independent heat sources.

You also don’t necessarily have to replace all radiators. Search for the tool Heizreprot. For a small fee, it provides a qualified assessment of which radiator requires which supply temperature to keep the room warm. Then you can replace the worst-performing radiators and possibly move some from one room to another.

Measuring rooms and radiators is not rocket science, and the different types of radiators are also relatively easy to distinguish.

1 liter of oil provides about 10 kWh of heating energy, assuming the burner does not lose any through the chimney.
The logic behind combining radiators with air conditioning is a bit weak: If the outdoor unit supplies a maximum of 15 kW, the fans cannot deliver more heat into the rooms. The supplied heat output must be shared between the radiators and the air conditioning units. So, there is even less available for the radiators than if they were operating alone. It would be different if you supplemented a heat pump with a separate air conditioning system: then you would have two independent heat sources.

The burner is serviced regularly, and the chimney sweep comes twice a year. During his last inspection, he confirmed with his measurements that my heating system is operating very efficiently.
However, we heat very generously and not at all sparingly. Basement, ground floor, first floor—all doors to stairways and hallways are always open. When my children and grandchildren visit, I always get told off for this, and also because they have to strip off layers due to the warmth. But being over 80, you just need it that way... My wife constantly feels chilly, even at 23 degrees Celsius (73 degrees Fahrenheit) room temperature... We didn’t work hard for 50 years just to put up with cold now. You younger people probably can’t understand that.
From what I understand, there are also several heat generators. The indoor units are probably supplied only with compressed refrigerant via thin pipes from the outdoor unit. This is then processed by an air-to-air heat pump inside the indoor unit. Or am I misunderstanding something?

Measuring rooms and radiators is not rocket science, and the different types of radiators are relatively easy to distinguish. Then you replace the worst radiators and perhaps relocate some from one room to another.

That’s a very good idea!

Yes, there are multiple heat generators, but they are all served by the same refrigeration circuit. What one takes, the other heat generator lacks. Only 15 kW are delivered. This nominal output is specified at +7°C (45°F); at -13°C (9°F), it will be less. That is exactly when you need the highest heating capacity.

Of course, you can heat all rooms to 23°C (73°F). However, with only 15 kW, this might be challenging. Did the domestic hot water (DHW) heating installer base your temperature requirements on your wishes, or only on the standard room temperature of 20°C (68°F)?