ᐅ Is a natural stone heating system practical when combined with a photovoltaic system?

Hello €uro,

€uro schrieb:

Yes, as long as they follow recognized technical standards (e.g., heat load calculation according to DIN 12831). Otherwise, I would have serious concerns.

I think I can put your mind at ease on this point; it involved a well-known engineering firm from Kassel.

€uro schrieb:

If, as you have confirmed here, ventilation losses exist but were not included in the balance, a deficit arises. How is that compensated? The standard heat load (capacity) is totally independent of the heat generator and energy carrier!

In this regard, you are acting like the proverbial farmer in the Rhineland: “what he doesn’t know, he won’t accept.” There is no need to compensate because stone or radiant heating does not rely on air as a heat carrier. Instead, what it requires is a massive masonry; ideally one with a thermal transmittance of 0.23 W/m²K or better.

€uro schrieb:

Then try building a partition wall behind Grandma’s tiled stove made, for example, only of cardboard and stand behind it. The sense of comfort will be gone.

That’s far-fetched since no one would do that; I assume you know that as well...

€uro schrieb:

In my own planning, I sometimes also use electric heating (infrared) for limited temporary peak load coverage when additional water heating, for example, is not possible. Especially with heat pump systems, as it makes no sense to reduce the overall system efficiency just for a few square meters (square feet) of bathroom space.

That is one way of using it; I was referring to the fact that with currently affordable photovoltaic electricity, heating an entire house with this system becomes very interesting.

€uro schrieb:

Are you seriously expecting electricity prices to drop? Let’s stay with electric direct heating:

What I have or have not expected is irrelevant since these “calculations” ended during discussions with one of the executives at RWE!

To give you some insight into the “thinking” of energy companies, here is an example. Around the turn [of the century] — about half a year before I sold this heating system — a Swiss inventor developed a device that managed to convert electricity in the air back into usable electrical energy. Well, today he is out of business because that electricity producer bought the patent and keeps it under lock and key. If I remember correctly, it was called an “ion exchanger,” and it seriously threatened the energy suppliers, even now, because the mere existence of such a device would fundamentally endanger their investments — ultimately financed by the end consumer — and their profit margins.

€uro schrieb:

With insufficient system design, significantly higher consumption can be expected in some cases. Overall, this is a purely consumption-based view, which must be complemented by investment or capital service considerations with regard to cost-effectiveness.

Setting aside that I cannot follow your calculations, I negotiated heat pump tariffs with several municipal utilities for this heating system; at the time, they were around 0.15 €/kWh with two or three shutdown periods of up to two hours each. These shutdown periods lowered room temperatures by no more than about 2°C (3.6°F). It should also be considered that for this system, the builder only has to bear upfront installation costs once; maintenance or replacement costs are completely excluded.

€uro schrieb:

I cannot see an absolute or generalized “pro” for stone heating.

I have never stated that in this way — I only made the mistake of saying that, for me, it remains the best heating system, especially combined with photovoltaic panels. I worked with it for a long time and lived with it — the comfort level is comparable only to that of a controlled ventilation system, and I miss it.

We will extensively renovate our house and have decided against selling it. If affordable external insulation between the brick facade and interior masonry becomes available — as we will not accept internal insulation — then this system combined with photovoltaic panels will definitely be installed. I am tired of being cold when I come out of the shower, fed up with feeling hindered in breathing by warm ambient air, and certainly tired of sending money to the chimney sweep or plumber every year or having to build reserves for a new heating system in 15 years right after installing a new one!

Let’s end the discussion on this topic here. I acknowledge that I am technically outmatched, and you are unwilling to let things slide; that’s perfectly fine, I accept it. You, in turn, accept that I have expressed my personal opinion without claiming exclusivity.

Best regards

€uro schrieb:
How can you as an end user benefit from this? Do you get the electricity for free or receive a bonus when you consume it?

Regards.

As an end user, unfortunately, there is currently no benefit. The additional margin remains with the large companies. And yes, they received a bonus during the times mentioned above for taking the electricity (= negative electricity price).
Night storage heaters were only economical because production was high and consumption was low at night. To get rid of the electricity, the utilities lowered prices for such devices at night.
Now, the problem of excess supply at low demand is no longer at night, but during the day – so sooner or later, the night tariff will likely become a midday tariff...

Regards
Micha

Micha&Dany schrieb:
...Now the problem of high supply with low demand is no longer at night, but during the day – therefore, sooner or later the night rate might turn into a midday rate...

Demand-based tariffs are certainly conceivable. How they will look is unknown today, so there is no reliable basis for planning.

Owners of air-source heat pumps already tend to use midday hours, for example, for hot water generation. So that would fit.

Best regards

Hello construction expert,

Bauexpert schrieb:
...Regardless of the fact that I cannot follow your calculation method, I negotiated the heat pump tariff with several utility companies for this heating system; at that time it was 0.15 €/kWh....

The 0.19 €/kWh is a current mixed calculation based on peak/off-peak rates. You can also apply different prices for the respective energy sources to the figures mentioned.

For a building with a heating energy demand of 15,000 kWh (15,000 kWh), the heating system would need to harvest energy at a “zero cost” using a photovoltaic system (system size):

Air-source heat pump: => 4,286 kWh/a (4,286 kWh/year);
Ground-source heat pump: => 3,333 kWh/a (3,333 kWh/year);
Electric marble heater: 15,000 kWh/a (15,000 kWh/year)

Building with 2,500 kWh (2,500 kWh) heating energy demand:

Air-source heat pump: => 714 kWh/a (714 kWh/year);
Ground-source heat pump: => 556 kWh/a (556 kWh/year);
Electric marble heater: => 2,500 kWh/a (2,500 kWh/year)

The share for domestic hot water would be added.

Bauexperte schrieb:
...
Let’s end the discussion on this topic here.

Fine, everyone should do what they are convinced of (became convinced of).

Best regards

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