ᐅ New heating system with domestic hot water production?!

Good morning,

After a long search, we have found a house. It has a gas heating system installed (1997) that is only used for heating. For hot water, a tankless water heater is installed.
Of course, the energy certificate is not very impressive. The house was fully renovated in 2013 and has about 145m² (1560 sq ft) of living space.
Suggestions on the energy certificate:

• new gas heating system with a condensing boiler
• for hot water: solar combined with gas heating system with a condensing boiler

I have already consulted two heating companies here. They are not convinced about solar solutions. Their suggestion was just to install a storage tank (60 L (16 gallons)) and that’s it.

Do you have any other suggestions or ideas for hot water preparation?

Thanks in advance

Best regards

Steven

I would also avoid solar thermal systems. The money would be better spent elsewhere. An ecological alternative could be a domestic hot water heat pump. Keep in mind that hot water production only requires a small portion of the energy compared to heating, so complex systems usually don’t pay off. Gas or, for a small number of occupants, an electric instantaneous water heater are more economical.

If gas heating is already decided, I would also use it for hot water, plus install as much photovoltaic (PV) solar panels on the roof as space allows.

Photovoltaics are cost-effective thanks to subsidies, regardless of the heating system, and the electricity generated can be used for much more than just producing hot water from solar energy. For example, a domestic hot water heat pump can be powered mostly by self-generated electricity throughout the year. Still, I would probably stick with gas for hot water.

Since the house has one room with underfloor heating (bathroom) and the rest with regular radiators, will it be difficult to use an air-to-water heat pump or not?

There is also a fireplace in the living room.

Okay, then I will take a look there! Or rather, stay there.

Thanks =)

Unfortunately, this approach doesn’t work with a heat pump. The efficiency is determined by the "worst" room. For example, a living room with small radiators and large windows means a high flow temperature. Low-temperature radiators with active fans might be an option, but I have no idea about the cost. With a heat pump, planning needs to be very precise, calculating every room individually.

In an unrenovated older building, an air-to-water heat pump for both heating and hot water is almost completely impractical. A heat pump dedicated only to hot water combined with photovoltaic electricity could be operated economically, but this heavily depends on the specific conditions. A professional needs to assess and calculate this carefully.

However, if your boiler needs to be replaced soon or should be, and your entire remaining infrastructure is already designed for gas, it would be unwise not to use it. Gas isn’t that bad; modern condensing boilers are very efficient and economical. So why not take advantage of that?

If there are still old cast iron radiators somewhere, it makes sense both energetically and aesthetically to replace them with modern radiators. Investing money there is more worthwhile than installing an air-to-water heat pump.

From an economic standpoint, it is probably most practical to leave everything as it is.
Condensing technology was likely already installed in 1997. If the heating system basically works, replacing it just for the hot water doesn’t make sense.
In addition, pipes would need to be installed, which means opening up walls and possibly floors.
Are those going to be done anyway?