Is natural stone heating in combination with a photovoltaic system reasonable?

Hello €uro,

Yes, provided they adhere to recognized technical rules (e.g. heating load calculation according to DIN 12831). Otherwise, I would have serious concerns

I think I can reassure you on this point; it was a reputable engineering office from Kassel.

If, as you have confirmed here, ventilation losses are indeed present but are not considered in the balance, a deficit arises. How is that compensated? The standard heating load (performance) is completely independent of heat generator and energy carrier!

You behave in this matter like the proverbial farmer in the Rhineland: "what he doesn’t know, he won’t eat." It does not need to be compensated because natural stone or radiant heating precisely does not need air as a heat carrier. What it does need instead is a massive masonry; preferably one that can offer 0.23 W/m[SUP]2[/SUP]K or better.

Then try building a partition wall made, for example, only from cardboard behind grandma’s tiled stove. The feeling of comfort will be gone.

That’s far-fetched because no one would do that; I assume you know that too...

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

That is one form of use; I was referring to the fact that in times of cheaply available photovoltaic power it is more than interesting to heat an entire house with this system.

Are you seriously calculating with falling electricity prices? Let’s stick to electric direct heating:

What I have or have not “calculated” is completely irrelevant, since these “calculations” found their end in a conversation with one of RWE’s board members!

So you can somewhat understand the “thinking” of the energy companies, here is an example. Around the temperature of the flow - half a year earlier - when I sold this heating system, a Swiss tinkerer developed a device that enabled him to convert the electricity in the air back into usable electrical energy. Well, he is bankrupt today because this electricity producer bought the patent and has kept it securely ever since. If I remember correctly, he called it “ion exchanger” and it would have seriously put the electricity companies in a tight spot; still today, because the mere existence of such a device would existentially threaten their investments – which end consumers ultimately finance – and profit margins.

With insufficient plant planning, significantly higher consumption is to be expected in some cases. Overall, a purely consumption-side consideration, which must be supplemented by investment or capital service in terms of economic efficiency.

Regardless of the fact that I cannot follow your calculation method, I had negotiated the heat pump tariff for this heating system with several municipal utilities; at that time it was 0.15 €/kWh with 2 to 3 switch-off periods of max. 2 hours each. These switch-off times lowered the room temperature by no more than 2°. Furthermore, it should also be considered with this system that a builder only has to consider one-time construction costs; maintenance or replacement costs are completely omitted.

I cannot see an absolute or blanket "pro" for natural stone heating.

I have never stated that at any point – I merely made the mistake of writing that, “for me” it is still the best heating system; especially in combination with photovoltaics. I have worked with it for a long time and lived with it – the feeling of comfort is roughly only comparable to controlled residential ventilation and I miss it...

We will thoroughly renovate our house, we have decided against selling. If subsequent insulation between the clinker and the inner masonry is affordable – we will certainly not accept interior insulation – then this system alone in combination with photovoltaics will definitely be used. I am tired of freezing after getting out of the shower, tired of “feeling” restricted in breathing due to the warm ambient air and definitely tired of paying the chimney sweep or the installer money year after year or even having to build reserves immediately after installing a new heating system for the future (in 15 years)!

Let us end the discussion on this topic here. I am technically inferior to you and you are not willing to let things be “as they are” – that is okay, I accept it. You in turn accept that I have expressed my subjective opinion without any claim to exclusivity.

Kind regards

How can you as an end user benefit from this? Do you get the electricity for free or a bonus if you consume it?

v.g.

As an end user, unfortunately, you don’t benefit from this at all currently. The additional margin remains with the large companies. And yes, they did receive a bonus at the aforementioned times for taking the energy (= negative electricity price).
The night storage heaters were only economical because there was high production and lower consumption at night. To get rid of the electricity, the utilities therefore lowered prices at night for such systems.
Now the problem of high supply with low demand is no longer at night, but during the day – ergo: sooner or later the night tariff will probably turn into a midday tariff...

Regards
Micha

...Now the problem of high supply with low demand is no longer at night, but during the day - ergo: sooner or later the night rate will probably turn into a midday rate...

Load-dependent tariffs are certainly conceivable. What they will look like is unknown today, so there is no reliable planning basis. Air heat pump owners already preferentially use the midday period today, for example for hot water preparation. So that would fit.

v.g.

Hello construction expert,

...Regardless of the fact that I cannot follow your calculation method, I negotiated the heat pump tariff for this heating with several municipal utilities; at that time it was 0.15 €/kWh....

The 0.19 €/kWh is a current mixed calculation from HT/NT. You can also use other prices for the respective energy carrier for the numbers mentioned.

For the building with 15,000 kWh heating energy demand, a photovoltaic system would have to be harvested for a heating system at "zero tariff" (system size):

Air heat pump: => 4286 kWh/a;
Brine heat pump: => 3333 kWh/a;
el Marble: 15000 kWh/a

Building 2500 kWh/a heating energy demand:

Air heat pump: => 714 kWh/a;
Brine heat pump: => 556 kWh/a;
el Marble: => 2500 kWh/a

The share for hot water would be added.

...
Let’s end the discussion on this topic here.

Good, everyone should do what they are convinced of (was).

best regards

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