ᐅ Solar system, wood-burning stove with water heat integration, passive house, heating costs in winter

Hello!

We are currently planning our house construction. It will be a passive house without a basement, with about 260m2 (2800 sq ft) of living space and an open floor plan combining living room, dining area, and kitchen. The south and west sides around the living area will have large windows to let in plenty of natural light. Right now, we are considering the heating concept. Since one of our main wishes is to have a cozy tile stove in the living room, the idea of a hydronic system naturally comes up.

At the moment, we are leaning towards heating the whole house with solar thermal collectors and this hydronic stove (underfloor heating). Since we definitely want the stove anyway and have access to firewood ourselves, we think this could be a relatively cost-effective system.

We are now wondering how much and how often you actually need to heat with such a system during winter and how well these systems work in practice...

I would really appreciate any thoughts or suggestions. We are still quite early in the planning stage...

BauRat schrieb:
.... The plan is for a passive house without a basement, with about 260m2 (2,800 sq ft) of living space ......Since one of our main wishes is a cozy tiled stove in the living room, the idea of a water-based heating system arises.

Without precise sizing, this can be problematic. It is not uncommon for the rooms housing the stove to become overheated. How is the heat supposed to be distributed?

BauRat schrieb:
.... We are now wondering how much/how often we will actually need to use it for heating in winter and how well these systems work...

These questions are partly answered through the initial assessment => actual demand (capacity, energy) for heating and hot water.

BauRat schrieb:
....
At the moment we are still quite early in the planning phase...

That is a big advantage since time pressure is one of the worst advisors when it comes to building.

Best regards

[QUOTE=€uro]Without precise sizing, this can become problematic. It is not uncommon for the installation rooms to overheat in such cases. How is the heat supposed to be distributed?[/QUOTE]

The heat distribution is intended to be via underfloor heating. The stove will be located in the open living/dining/kitchen area, so it will be in the largest room of the house, allowing the direct heat generated to spread effectively.

It would be interesting to know how well these water-bearing (hydronic) systems perform and what distribution of heat output and input is possible.

BauRat schrieb:
...It should be done via underfloor heating.

I would reconsider that. Underfloor heating is slow to respond and doesn’t really suit the sometimes quicker processes of solar and internal gains.

BauRat schrieb:
...The stove is supposed to be located in the open living/dining/kitchen area,...

Then it should be placed centrally, for example as a room divider, and not “crammed” into a corner. The direct heat output should not be significantly higher than the calculated heating load of the room.
The cozy factor of the traditional tiled stove, like those from grandma’s times, largely depends on radiant heat. The intensity of radiation depends on the surface temperature.
Passive houses at suitable locations and with proper planning rely on air heating only, so no water-based heat distribution.
In less favorable locations, water-based heat distribution makes more sense, though it involves more effort.
There are situations where heating is not needed, but hot water must be produced and solar coverage is currently insufficient. In such cases, direct heat release in the room where the stove is located cannot be avoided.
Also, with a water-based stove, the storage tank might be charged due to hot water demand. Depending on the state of charge, any surplus solar energy later available cannot be used or is only used inefficiently. The economic efficiency of the solar thermal system can deteriorate significantly depending on user behavior.

In my opinion, tiled stoves, solar thermal systems, and passive houses don’t really fit well together. I would rather favor a heat pump and, if applicable, photovoltaic panels. With the right conditions, heating and hot water can then be provided almost at “zero cost” annually without any manual effort. If needed, a small wood stove can be installed in the large main room for occasional enjoyment of a fire.

Precise statements can only be made once the actual demand (power, energy) for heating and hot water as well as regional climate data are known.

Best regards

[QUOTE=€uro]I would reconsider this. Underfloor heating is slow to respond and doesn’t really match the sometimes faster dynamics of solar and internal gains.[/QUOTE]
Yes, I’ve read the same in a technical book… it recommended wall heating (is that the correct term?) for this situation. Somehow, though, I find the idea of underfloor heating more appealing… for things like hammering nails, hanging shelves, etc. But this will definitely be discussed further. Maybe I’ll have to let go of some “traditional” views to find the best solution.

--> The stove would really be placed centrally between the living room and dining room as a room divider, so it could also be used as a cozy spot for watching TV or reading.
A friend of mine heats with geothermal energy (ground collectors) and is quite enthusiastic about it – but I’m not so keen on the idea… all those pipes in the garden and the heat pump running on electricity.

I get my firewood from my own forest, so a log wood stove seems future-proof and cost-effective to me. Initially, a wood gasifier was the first choice, but as we move more toward a passive house standard, that now seems oversized. And as I said -> The tiled stove is a “must have” for us, so a hydronic stove seems quite attractive. I also work a lot from home, so heating in winter wouldn’t be a big issue.

I would be very interested if anyone has experience with this setup and how satisfied they are with it….

Thanks in advance for the food for thought.

The best option is surface heating systems, either wall or ceiling heating using a capillary tube system. A wall heating system is not simply an inverted floor heating system, as many believe. This approach is not only ideal for passive houses but also suitable for any other building type. The capillary tube system alone saves a significant amount of energy, and it also allows for cooling the building in summer by utilizing the ground temperature of 14–16°C (near-surface use).

Energiefuxx