Renewal of heating system in old building, which system?

So now there is another update:

Another company has now provided me with an offer for a solution with only an LW heat pump including calculation. Here are a few facts:

Heated QM area 200
Standard heating load 21.86 W / m2
Total heat generator output 11 kW
Heating load of the building 11kw
Coverage ratio of the heat pump 100%
Performance share of the heat pump 78.36%

Annual performance factor heating 3.9 without auxiliary heater and 3.9 with auxiliary heater
Annual performance factor domestic hot water 4.0 without auxiliary heater and 4.0 with auxiliary heater
Annual performance factor according to VDI 4650 -> 3.9

Flow temperature 55 degrees
Hot water storage 50 degrees

Performance coefficient COP A-7/W35 -> 2.71
Performance coefficient COP A2/W35 -> 4.28
Performance coefficient COP A7/W35 -> 5.61

We are potentially planning to install a photovoltaic system with 8.16 kWp and 9.6 kWh storage on our south-facing roof.
Calculated grid feed-in approx. 9262 kWh per year.
Currently, our own electricity demand is approx. 3000 kWh, later probably 4500 kWh.

Electricity consumption:
For electricity consumption, one would now calculate heating load divided by the annual performance factor multiplied by 2000 (heating hours) resulting in the following electricity consumption:
11 kW / annual performance factor 3.9 x 2000 = 5641 kWh, i.e. with an average kWh price of 30 ct approx. 1692 EUR / year (141 EUR / month) electricity costs for the LW heat pump.

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Questions:

1.) Do you think the calculation from the company is realistic? with an annual performance factor of 3.9 for LW heat pump?
2.) Are the electricity costs possibly too high?
3.) If it is uneconomical regarding electricity costs, would it become sensible and profitable again with the above-mentioned combination of a photovoltaic system?
4.) Is it actually allowed to ask here for experiences with LW heat pump models, as long as no prices etc. or advertising is made?

Thanks for your feedback.

Best regards
Mr. Wirtz

Performance coefficient Cop A-7/ W35 -> 2.71
Performance coefficient Cop A2/ W35 -> 4.28
Performance coefficient Cop A7/ W35 -> 5.61

Uh - W35 means heating water at 35 degrees, right? And you want to operate with a flow temperature of 55 degrees? I wonder what the Cop will look like then? And then your electricity bill. LOL

We are possibly planning to install a photovoltaic system with 8.16 kWp and a 9.6 kWh storage on our south roof.
Calculated feed-in to the grid approx. 9262 kwh per year.
Currently, our own electricity consumption is about 3000 kWh, later probably about 4500 kWh.

I think photovoltaics are great. Storage useful? Rather not, or currently not really profitable. How much does that cost?

Just briefly summarized about your investment. You want to replace an oil heating system, which causes heating costs of about €1,150 per year, with a highly efficient heat pump, where you expect heating costs of €1,700 per year. Find the mistake!

Let specialists handle it and calculate...

The flow temperature is definitely calculated too high at 55 degrees. That is too high even for a gas condensing boiler. In the old building with radiators, I operate at ~40 degrees with NAT

Uh – W35 means heating water at 35 degrees. And you want to operate with a flow temperature of 55 degrees? What will the COP look like then? And just wait for your electricity bill. LOL

I think photovoltaics are great. Storage useful? Rather not, or currently not really profitable. How much does this cost?

Just briefly summarized for your investment. You want to replace an oil heating system that causes you heating costs of about €1,150 per year with a highly efficient heat pump for which you expect €1,700 heating costs per year. Find the mistake!

Specialists should take a look and calculate...

Yes, that’s correct, that is the standard value for a flow temperature of 35 degrees. I just checked the product provider’s website, and there is no specified value for W55 there. Could this somehow be calculated or approximated? Would it make sense to operate the system with only 35 degrees flow temperature?

Or why is the calculated annual performance factor not a benchmark for our electricity consumption? It was calculated by the heating company at 3.9, right?

The photovoltaic system, net and including storage subsidy, should cost about €19,000.

The flow temperature is definitely calculated too high at 55 degrees. That is too high even for a gas condensing boiler. I operate an old building with radiators at about 40 degrees with NAT.

We have the particularity that the first floor and basement are equipped with underfloor heating (separate heating circuits) and the first floor still has tubular radiators. We want to replace these with low-temperature radiators with a flow temperature of 55 degrees. Possibly then we could also "operate" these only with 35 degrees?

Thanks for your help.
Best regards

Yes, that's the standard value for VLT35 degrees. I just checked on the product provider's website, there is no specified value for W55. Could this be somehow calculated or upscaled? Would it be sensible to operate the system only with a 35-degree flow temperature?

That should be calculated by someone who knows about it. Unfortunately, I cannot.
I can only tell you from experience that you will get real problems with the flow temperature in winter. Some poorly designed systems in new buildings only get through the winter with an electric heating rod = COP 1 at lower temperatures. And they only need 30-35 degrees flow temperature with complete underfloor heating.

The photovoltaic system should cost about EUR 19,000 net including storage subsidies. 8.16 kWp should cost around T€ 10 plus storage minus subsidies.

19 net and the subsidy is already deducted? Not worth it and also too expensive.

What do you say about my calculation of your electricity costs vs. oil costs without renovation?

....What do you say about my calculation of your electricity costs vs. oil costs without renovation?

Yes, somehow an error in the system :-O But which one? Could it be that the heating load of 11 kW was calculated too low?

The heating company said that with the offered air-water heat pump (two outdoor units) the heating output is sufficient, even without heating rods. And that I will have about 4000 - 5000 kWh electricity consumption.