ᐅ Which heating system? Requesting recommendations

Have a heat load calculation done and get advice from someone knowledgeable. In the long term, an air-to-water heat pump is rarely the best choice.

If a gas condensing boiler without extras can be approved, that would certainly not be a bad option, but then it might also be worth considering an air-to-air heat pump...

We have a Nibe750 exhaust air heat pump with decentralized ventilation (+ underfloor heating). I don’t understand why this type of heating system is often criticized so much (especially by people who haven’t installed it themselves but just spread hearsay).

We live in a solid construction house with 160 sqm (1,722 sq ft), and a heating load calculation was carried out. The system was configured on-site during a 4-hour training session directly by Nibe.

Even in winter at -10°C (14°F), the electric backup heater has never switched on.

I cannot confirm the claim that it’s an electricity guzzler. There is always fresh air inside the house, no lingering odors, and a pleasantly consistent temperature. I wouldn’t want to be without it 🙂

Previously, we lived in a semi-detached house with a gas condensing boiler, and for us it was immediately clear that we did not want that for our own home.

If you ask 10 people, you will probably get 10 different opinions 🙂

rockalilly schrieb:
We have a Nibe 750 exhaust air heat pump with decentralized ventilation (+ underfloor heating). I don’t understand why this type of heating system is always spoken badly of (especially by people who haven’t installed the system themselves but just spread hearsay).

We live in a solid construction house with 160 sqm (1,722 sq ft), and a heating load calculation was carried out. The system was set up on-site during a 4-hour training directly by Nibe.

Even this winter, with temperatures as low as -10°C (14°F), the electric backup heater didn’t turn on once.

I cannot confirm the claim that it consumes a lot of electricity. There is always fresh air in the house, no odors linger, and the temperature is pleasantly even. I wouldn’t want to miss it anymore 🙂

Before, we lived in a semi-detached house with a gas condensing boiler, and it was immediately clear to us that we didn’t want that for our own home.

If you ask 10 people, you’ll probably get 10 different opinions 🙂

What insulation standard do you have? Approximately where do you live? (The recent winters here, in North Rhine-Westphalia, have been quite mild). So you have an exhaust air heat pump that uses the energy from the exhaust air to heat the underfloor heating system? So not an air-to-air heat pump, but an air-to-water heat pump? Does decentralized ventilation mean that cold air flows in in the same quantity as the exhaust air pump extracts?

What was your exact electricity consumption for the system over the last 365 days?

So, the 750 model is definitely a great device, no question about it. And there is a lot of nonsense written about it in forums, especially by people who have no experience with it. The main issue we face in Germany is the Energy Saving Ordinance. Thanks to many options and adjustments, it’s possible to turn a slow horse into a racehorse. Comparisons have been made between different heat pump systems plenty of times. But in Germany, no equivalent houses were compared; it was just a stamp of approval for xyz and then the comparison. If I really compare equivalent houses now, I find a difference, for example, between the 750 and the 1225 (as a ground source heat pump) of about 8 kWh/m²/year. For around 140 m² (1500 ft²), roughly 1100, I’m not in the mood to do the math, about 250 bucks per year.

Now let’s look at the investment costs. The 750 is about a grand more expensive than the ground source heat pump. But then you have to consider the heat source, plus a controlled residential ventilation system (admittedly, that’s the downside), but the difference is around 10,000.

Now you can calculate for yourself when the extra effort is worth it...

And that heat pump salespeople have completely crazy prices is something you don’t even need to argue about 😀

However, the many disadvantages of Nibe / exhaust air heat pumps should also be mentioned; there are many negative reports from people who actually have one! Your calculation is very much an estimate... If the insulation is too poor and the heating load is already 6 kW at -10°C (14°F) in a cold region (frequent and long-lasting), how can an exhaust air heat pump heat effectively? It has to extract 6 kW of power from the indoor air (extreme air volumes!), while cold air flows back through the inlets, which then also needs to be heated (requiring even more energy). This can only work reasonably well if the house is very, very well insulated. One of my neighbors has better insulation than I do, but with the same floor area, much higher costs and is unhappy with the drafts. This is based on actual experience.
Therefore, when recommending exhaust air heat pumps, it is extremely important to consider how and where the building will be constructed. As a general rule, I would rather advise against them.

This is how it looks... it’s simple physics, so you don’t necessarily need experience with the system... an air heating system works great in Spain, but here with us it requires additional measures.