Combination unit ventilation / heat pump or separate units

It should be an air heat pump.

We will definitely stick more to what the heating engineer says. It only unsettles you when you get different advice. He just said that he doesn't particularly like the company Stiebel, but he generally didn’t say anything against combined units.

Thanks for your tips, tomorrow we will meet with the heating engineer.

Is there a real advantage between separate devices and a combined unit?

With the combined unit, we already have concerns about the space requirement because the air heat pump is also located in the basement. The air pump was planned in front of the house.

Best regards

You do realize that the heating engineer is ultimately a salesperson?

Have a heating load calculation + heat demand calculation done.

With that, you can calculate for yourself whether such an air heat pump together with controlled residential ventilation even fits or if in winter the electric heating element runs continuously.

First, you have to know what heating capacity is required in winter at the design temperature (-x degrees depending on location). Then you calculate your heat demand based on the desired room temperatures.

With that, you can then compare the power consumption of the systems.

Simple example. Heat demand 12,000 kWh including hot water. Air heat pump with real annual performance factor of 3: 12,000 ÷ 3 = 4,000 kWh power consumption.

Ground source heat pump with real annual performance factor of 5: 12,000 ÷ 5 = 2,400 kWh power consumption.

1,600 kWh electricity saved at €0.25/kWh results in savings of almost €400 per year.

If you now build an honest KfW40 or passive house, the calculation naturally looks different. The saving potential becomes very, very small there.

By the way, you currently get very good subsidies for geothermal energy! (€4,000–5,000) Please take this into account! There are also very, very good alternatives to geothermal energy (drilling), such as geothermal baskets or trench collectors. Trench collectors can be made for just under €1,000. Or arranged through one of the providers (ask in the forum) as well....

P.S. The heating load calculation also includes a pipe network calculation for the underfloor heating.....