Heating 2 bathrooms each 3.5 m² - General heating question

Hello,

we are currently finalizing the purchase of a house and are still completely undecided about the heating question. The old oil heating system, 50 years old, must be removed along with all the pipes and radiators.

So far, we have been considering the idea of a heat pump in combination with a wood stove with a water jacket.

For that, we would have to or want to retrofit underfloor heating on about 65m2 on the ground floor.
The whole thing would then cost around €80,000 in total.

Now the idea has come up to heat with climate split units and to use a normal wood stove in the large room on the ground floor for the atmosphere and cold days.
This would save us a lot of money on the installation of the entire heating system, but we encounter a problem.

How should we then heat the two small bathrooms? They are each 3.5m2 and are supposed to be the warmest rooms in the house at 22 degrees.

Do you have any ideas on how something reasonable could be realized there?

Many thanks and best regards

Many people use these electric towel warmers for that.

Or you simply do without and leave the door to the bathroom open. That’s how I knew it from my youth and that’s how we currently handle it as well. Quickly dry off and get dressed after the shower, then everything works out.

Thank you,

both bathrooms border hallways that will be heated very little. So no heat would get in there.

You can’t install an indoor unit of a split system in the bathroom, right? Sure, a draft is totally counterproductive, but the unit doesn’t have to run while showering, rather to heat around showering. Or is that not possible because of the humidity?

A conventional electric heater would certainly be very expensive if it had to keep the bathrooms constantly at 22 degrees.

Best regards

The towel heaters are used more as an addition. With underfloor heating, there is also the problem that you have very little space in the bathroom but possibly want the highest temperatures. And 3.5 sqm is not much. Probably half an hour of preheating with a proper fan heater is enough. One idea for the morning showers would be to connect it to a timer shortly before the alarm clock. I can't say much about the split air conditioner.

A conventional electric heater would certainly be very expensive if it had to keep the bathrooms constantly at 22 degrees.

You only run electric heaters when you use the bathroom. Take a look at infrared heaters. They are suitable for something like that. There are even mirrors that heat.

for that we would have to or want to retrofit underfloor heating on about 65m2 in the ground floor.
The whole thing would then be around €80,000 in total.

Now the idea came up to heat with climate split units and to still use a normal wood stove in the large room on the ground floor for the atmosphere and cold days.

Overall, you can do it that way. How big is the house? How many rooms and m²?
The house is probably at least 50 years old, or even older? What is the general energetic condition?

There are multi-split units with up to 4 indoor units and by now also inconspicuous indoor units in picture-frame form, maybe that would be a solution for the bathrooms. They have about 60 cm edge length square. Alternatively, indoor units for ceiling installation, if it’s suspended anyway or will be. Certainly still endlessly oversized for 3.5 m², but somehow it has to get warm.
I would not heat the bathroom only "indirectly" through the other rooms. 1. Uncomfortable, then better the other way around and 2. problematic in terms of moisture. The most humid room is the coldest ... not a good idea.

The lower the energy demand, i.e. the better insulated, the easier it is to maintain and also install infrared panels there.
With the energetic standard from 1970, I would still improve (roof insulation, possibly from the inside, and at least interior insulation in the bathroom area if there is no complete facade insulation).

If you roughly calculate: bathroom with 3.5 m² and 150 kWh per m² in an uninsulated old building results in about 500 kWh heating demand per year.
Direct heating with infrared: 500 kWh electricity
Via split unit with SCOP = 4: 125 kWh electricity
The 375 kWh is €100 in 2022 and €150 - 200 savings in the coming years. I would rather hang a small indoor unit there.

Direct heating with electricity is only feasible without high follow-up costs if the energy demand per m² is low.
The approach via climate split units (+ domestic hot water heat pump) is sensible though.
If you compare €80,000 with the cost for 2 multi-split units each with 4 indoor units (2*€10,000) and domestic hot water heat pump (€4,000), and at the same time need less electricity (SCOP of multi-split units is significantly better than heat pump in existing buildings with high flow temperature), the question basically doesn’t arise. For comfortable radiant heat in the living area a wood stove (then without water jacket, but with solid mass or even as a tiled stove) and that’s it.

I myself also considered doing that with a planned renovation, but the purchase did not work out ... but the seller also has had no success with his price expectations and the price trend for old properties is currently rather going down.