ᐅ From what point does it become worthwhile to install a heat pump in an older building?

Hello,

In an older building, there is currently an oil heating system that is planned to be replaced with a new heating system. The question is whether a heat pump is worthwhile, as it is subsidized at 45%, correct?

Therefore, the question is whether it makes sense to invest in it. Here are the details of the house:

• Solid construction from 1970
• Basement: fully cellar, ceiling height 201 cm (79 inches), exterior insulating coating, 11.5 cm (4.5 inches) solid sand-lime brick 1.8/250
• Ground floor/attic: 11.5 cm (4.5 inches) solid sand-lime brick 1.8/250, 2 cm (0.8 inches) expanded polystyrene, 17 cm (7 inches) sand-lime brick 1.4/150
• Roof: collar beam roof with concrete tiles, insulation also present

Of course, we plan to install underfloor heating. Given the information above, does a heat pump make sense at all? Or would it be better to opt for a gas heating system?

bestaik schrieb:

Of course, we would install underfloor heating here. But does a heat pump even make sense with the data mentioned above? Or would it be better to go for a gas boiler?

What has your heating demand / consumption been so far? What further measures are you planning? What does the engineering firm say about the room-by-room heat load calculation or heating system design?

I can tell you that this winter, in my (still) uninsulated mid-1960s building with new underfloor heating, mostly new windows, and basement ceiling insulation, I didn’t exceed a flow temperature of 30°C (86°F) for an indoor temperature of 21.2–22°C (70–72°F). The energy cost is about half of my previous oil consumption (which has shifted even more strongly in favor of the heat pump over the past few weeks).

Benutzer200 schrieb:

What have your heat demand / consumption been so far? What additional measures do you have planned? What does the engineering firm say about the room-specific heating load calculation and heating system design?

I can tell you that this winter, in my still uninsulated mid-1960s building with a new underfloor heating system and mostly new windows plus basement ceiling insulation, I didn’t need to exceed a 30°C (86°F) supply temperature to achieve an indoor temperature of 21.2–22°C (70.2–71.6°F). The energy cost is about half of the previous oil consumption, which has shifted even further in favor of the heat pump in recent weeks.

We just bought the house and therefore can’t say much yet. I thought there might be some general guidelines, for example whether a house requires insulation level X or not.

Anyway, the heating system needs to be replaced regardless. The question is whether it will be a heat pump or a gas boiler with solar thermal, both of which are technically feasible.

In general, it should be possible to install a heat pump, right?

bestaik schrieb:

So, is it generally possible to install a heat pump as well, right?

Correct. If you switch entirely to underfloor heating, a heat pump would be a good alternative. Possibly combined with a photovoltaic system. 😉

The search for a gas provider will probably give you the answer. ;-)

In general, every house can be operated with a heat pump. It just varies in complexity. Underfloor heating is already a great advantage. An insulated roof as well. Then make sure there are no drafts anywhere and insulate the basement floor from below as a DIY project. After that, use various forums to properly size the heat pump, omit the buffer tank, and you will heat cost-effectively and in an environmentally friendly way.

It would actually be helpful if you could get some data from the previous owner, such as oil consumption and room temperatures. This way, you can make initial rough estimates of how well or poorly the house is insulated.

Deliverer schrieb:

The search for a gas provider should already give you the answer. ;-)

In general, any house can be operated with a heat pump. It’s just a matter of how much effort is required. Underfloor heating is definitely a great prerequisite. An insulated roof as well. Also make sure there are no drafts and insulate the basement from underneath with your own work. Then, with the help of various forums, properly size the heat pump, leave out the buffer tank, and you’ll be heating cheaply and environmentally friendly.

In fact, it would be helpful if you could get some data from the previous owner, such as oil consumption and room temperatures. Then you can make initial rough estimates of how well or poorly the house is insulated.

OK, thanks a lot. The oil consumption is easy to answer, but temperature? Hmm, hard to say, it’s an older lady. The heating was set to 2–3 and it was definitely warm at single-digit temperatures outside. Radiators with fins are installed there.

Of course, I would also replace the windows here; these are double-glazed windows, so there is more to be done.