ᐅ Insulated Older Building from 1921: Converting from Gas Heating

Hello dear forum members,

We have been thinking for a while about what to do with our heating system in the long term. Of course, I have already read a lot, but we still don’t have a clear decision.

- The house is a well-insulated old building from 1921, a single-family semi-detached house. Currently, it is heated exclusively with gas; the boiler dates from 2010, is serviced annually, and is working perfectly.
- There is a two-flue chimney; one flue is connected to the gas heating system, the other is free.
- We currently use just under 11,000 kWh of heating energy per year; electricity consumption is about 2,200 kWh/year.
- The roof is a hipped roof, facing east, south, and west, with no shading at all. To put it plainly, it gets full sun all day long.
- The house is fully basemented, and we have quite a lot of space in the cellar, which has a floor area of approximately 40 m² (430 ft²). It is a vaulted cellar with enough headroom to stand comfortably. Slightly damp, consistent with the building’s age.
- We do not have any underfloor heating anywhere. The radiators are modern, some installed as recently as 2017. The house has a timber frame construction, masonry walls, the roof is very well insulated (2017), the facade was well insulated in 1993, and the wooden beam ceilings are filled with slag. The windows are almost all well insulated from 2017, with only three still having double glazing from 1993.

We would like to avoid heating with fossil fuels. At the moment, I’m leaning toward a pellet boiler combined with solar thermal.

Does anyone have other ideas?

Winniefred schrieb:

Does anyone have any ideas?

Have a room-by-room heating load calculation done as the first step. Only then will you really know if the old building is well insulated. After that, consider the heating system.

Winniefred schrieb:

We would like to heat without fossil fuels. At the moment, I am leaning towards a pellet heating system plus solar thermal.

No fossil fuels, but burning wood? How does that fit together?
Solar thermal makes no financial sense. Hot water in summer that you don’t need, and it doesn’t work properly in winter.

Winniefred schrieb:

Of course, I have already read a lot, but we are still not completely convinced.

Then heat pumps plus photovoltaics should have come up in your research 😉

This is a heat pump versus pellet topic where I would prefer the heat pump. Less maintenance, no chimney sweep required. First, however, the feasibility needs to be considered: Does your heating system allow you to read the flow temperature and volume flow? Are the new radiators type 33?

Benutzer200 schrieb:

Have a room-by-room heating load calculation done as the first step. Only then will you really know if the old building is well insulated. After that, you can consider the heating system.

No fossil fuels, but burning wood? How does that fit together?
Solar thermal is financially unreasonable. Hot water in summer that you don’t need, no function in winter.

Then heat pumps plus photovoltaics should have come across your mind 😉

Thanks for your answer.

So, wood is not a fossil fuel but biomass; it is renewable and sourced locally.

Friends of ours have had solar thermal (with gas backup) for 5 years, and during the warm half of the year their gas heating is completely off because solar thermal covers everything. Of course, it’s only a supplement. I can certainly ask about a heating load calculation, but from experience, it’s almost impossible to find tradespeople, especially for such “vague” jobs. The fact that the house is well insulated is already indicated by our gas consumption, which is well below average for a four-person household—but of course, the calculation is necessary, I agree with you on that.

CC35BS38 schrieb:

This is a heat pump versus pellet topic where I would prefer the heat pump. Less maintenance, no chimney sweep required. But first, you need to consider feasibility: Does your heating system allow you to read the supply temperature and the flow rate? Are the new radiators type 33?

These are questions I can’t answer off the top of my head. We basically do everything in the house ourselves, but heating is one area we don’t handle. I will look into it. I also need to check what type of radiators they are; type 33 doesn’t mean anything to me.

I hadn’t read much about heat pumps yet. It is often mentioned that they work well in combination with underfloor heating and are generally difficult to retrofit in older buildings. A complete renovation of the house (renewing all the floors) is rather not an option.