Vestaxx window heating - experiences?

... The heat pump house will never become a plus-energy house, and amortization is out of the question...

Underfloor heating pipes are subject to constant expansion and contraction. Although only millimeters, leaks can develop over the years.
Pumps, compressors, and valves are naturally more vulnerable and must be replaced more often. The parts may not be that expensive, but the replacement can easily cost 800 - 1000 €. This must of course always be taken into consideration.
...

oh man, always the same nonsense about making the inefficient heating look better through photovoltaics...

Instead of addressing my calculation specifically, it is suddenly omitted again that with the air-water heat pump you also have photovoltaics, even though we already agreed that it always makes sense. It would be just as valid to say: I have €25,000 left over and buy myself an electric car with it and thus save thousands of euros in diesel. That is nonsense! Such investments must be evaluated strictly separately.

A very cheap trick to always pretend you can only afford photovoltaics with direct heating. With every message, this company becomes more and more dubious to me!

Nonsense: As proof, here are my current daily figures: (KfW40+ / Passive house with brine-water heat pump - about 130m² semi-detached house with 2 residential units, 3 people) 6.5KWp system 45° tilt 100% south, 3.9KWh battery.



Special treat: My car (BEV) has also driven 11,744 km since November!! That adds about 18KWh per 100 km plus (energy surplus).

So far, I haven't said anything on the subject. But I also thought that with a passive house I wouldn't need much heating. I’d just put a few infrared panels as pictures or mirrors in the house, and that would be enough. But the biggest demand is not heating energy but hot water preparation. That’s why I cannot accept your consumption figures. From what twisted world or parallel universe do those come?

P.S. Of course, I was lucky with all the subsidies for KfW40+ but otherwise the "break even" with electric heating comes faster than you can blink. Photovoltaics MUST be considered independently! These useless references to a DIN standard with its oh-so important full cost accounting for private construction customers is nonsense. If you actually do a full cost accounting over 20 years, electric heating can’t win. I hear from acquaintances the first contracts for 65 cents per kWh :-(

I have heard more often about torn heating lines on car windows than about leaking underfloor heating pipes. But this is just my personal perception bubble. Are there reliable figures on this (failure of underfloor heating and failure of window heating)? Because both glass and the heating lines applied (or embedded) on it have different coefficients of thermal expansion...

Basics of rotor motor:
150m² with 40kWh/m²a -> 6000kWh/a heating energy demand / electricity price 35c/kWh / 4 persons (I’ll assume for now)
What was forgotten? -> Hot water (is done by the heat pump) -> 4 persons approx. 2000 kWh (12.5 kWh/m² then rounded up)
House electricity for 4 people -> approx. 4,000 kWh

What else did I forget?

Oh yes

A heat pump house will never become a plus-energy house and amortization can no longer be spoken of.

I’m dying laughing – he has no arguments left and anyone who calculates the amortization of a photovoltaic system at 100 years – as you did in one of your last posts – should first educate themselves and not calculate such nonsense.
[...]
only ROTOR MOTOR is much smarter than all the others.

too bad that in the end the same total always comes up.

I will watch this here for a while longer and only respond to genuinely intended factual posts and questions.

That’s exactly what I don’t like and therefore my detailed note to "Kill your darling". Here is someone apparently rock-solid convinced of his product and clashes with everyone who questions it and raises concerns.

So, this annoys me so much here that I actually fired up Excel.



The result over usual financing periods, which also represent the target lifespan of the heat pump, does not surprise me at all. I see all my theses and warnings about the system confirmed. If anyone asked me, I would not recommend the window heating system to anyone.

Since the topic of sustainability was also raised, I briefly cross-checked that roughly. CO2e for German steel assumed around 2.5kg, PE floor pipe 17x2 with 2kg CO2e. Production overhead is calculated with a flat 25%.



By the way, I am also an engineer and occasionally deal with determining CO2 footprints at work, so I claim with my many years of expertise that these are good benchmark values.

The problem, of course, is the CO2e of the German grid mix. Before the war, there were ambitious goals, which I now seriously doubt given that East German brown coal plants are still running. I simply assume our government will reach the <25% of the 1990 target ten years later in 2040.

So I simply calculated the electricity. Unfortunately, I have very serious doubts that it will go that well!


The very sobering result with the input parameters I chose is that over a period of 15 years, 16 tons of CO2 including production costs and operation will be emitted. The longer we continue to run this, the worse the CO2 balance of the window pane heating will become.



Significantly worse balance of the window heating compared to the heat pump, naturally due to efficiency.

And now please do not argue with the free photovoltaic. I have already refuted that argument with the first calculation. Over the financing period, no significant cost differences arise; thus, photovoltaic should be regarded as on top in both cases. Moreover, it must be noted that from November to February, 63% of the day not a single photon from the sun hits the photovoltaic surfaces directly. So 2/3 is heated with the grid mix and the last 1/3 is usually so cloudy that even the 15 kWp south-facing photovoltaic system cannot cover the basic consumption of the house without heating. A few sunny days make up for it again, provided no snow is on the modules.

Photovoltaic and heating must be strictly separated for the consideration. Therefore, it seems highly unfair to me that advertising for the heating system is done here with the free photovoltaic.

Since I haven’t had enough yet, I’ll immediately take another look at my heating load calculation and ask a few critical questions regarding heating the basement and my bathrooms, where I cannot install large window areas.