ᐅ Solar and hydronic heating insert

Hello everyone,

We are currently planning our new single-family home. We are building a solid masonry house (MZ7 brick) and expect to achieve an energy standard of around KfW55 / KfW40.
It will be a well-insulated house. We are a household of four people.

For heating, we plan to install a wood-burning stove with a water jacket on the ground floor. The stove will probably have an output of about 10 kW, with up to 70% of that output used for heating water.

On the roof, there will be a solar system (15–20 m² (160–215 sq ft)) intended for domestic hot water and to support the heating system. We want to use only one storage tank: a buffer tank with an integrated domestic hot water coil (spiral) at the top section.
The buffer tank will also include an electric heating element for emergency use, in case we have no sun and do not want to use the wood stove.

About 200 m² (2,150 sq ft) of living space needs to be heated. We have underfloor heating throughout the house.

The solar system will be installed on the southwest-facing roof. We have a total of 40 m² (430 sq ft) available there. The area not needed for the hot water system will be equipped with photovoltaic modules for electricity generation.

I wanted to ask if anyone has experience with this kind of heating concept and could share some advice.
Do you think the stove’s output will be sufficient?
How large should the solar area be?
What size buffer tank do you recommend?

Thank you very much for your help.

Best regards,
Michael

Hello,

Micha1893 schrieb:
... We are building a solid masonry house (MZ7 stone). In terms of standards, we will probably achieve KfW55 / KfW40... So it is a well-insulated house.

The actual standard depends not only on the building’s thermal envelope. 😉

Micha1893 schrieb:
... The solar system will be installed on the roof (southwest orientation). ... The rest, which is not needed for hot water, will be equipped with photovoltaic modules for electricity generation.

Has a professional performed a detailed energy balance, or are these just personal assumptions?

Micha1893 schrieb:
... What do you think, is the output of the stove sufficient?
How large should the solar collector area be?
How many liters should the buffer tank hold?

These questions should be clarified by the HVAC engineer. However, I am almost certain that a small heat pump combined with photovoltaics would probably be a better concept. 😉

Best regards

Micha1893 schrieb:
Do you think the stove’s capacity is enough?

You can’t say that without further information. A heating load calculation is necessary. This calculation shows the heating demand of the house with 4 occupants.

The following documents are needed for the heating load calculation:
- Thermal insulation calculations for the new building, including information about component areas and insulation values, ventilation technology, etc.
- Planning documents (floor plans, sections, site plan)
This calculation can be done by a plumbing, heating, and air conditioning (PHAC) specialist or a qualified engineer.

If an independent air wood stove is used, it is also advisable to contact the local chimney sweep to determine the requirements for any possible inspection or approval.

Micha1893 schrieb:
How large should the solar collector area be?

First, it must be clarified which type of system will be used. Domestic hot water solar thermal or solar thermal for heating support? Vacuum tube technology or flat plate collectors?

Micha1893 schrieb:
How many liters should the buffer tank hold?

This can only be answered after clarifying the above questions.

Best regards

T.H.