Is a multisplit air conditioner suitable for heating?

There is a reason why this type of heat pump heating has not become established (not to mention the poorer performance in winter).

Poor performance in winter, yes, you get that with an air heat pump. However, it does not matter how you distribute the heat in the house as long as you do not have to heat radiators to 50 degrees...

That's right, it's always about warming up the room air so that the living beings feel warm.
Air is — as you pointed out except in the case of infrared — what is ultimately warmed up.

An air conditioner is perceived as unpleasant because of the "draft." Underfloor heating is classified as comfortable due to the good distribution without hotspots.
Radiators and stoves simply warm up one corner because the air is not stirred.

You are quite clever :)

Hi, please don't take this the wrong way, but I have been active in forums for some time to discuss this question. Unfortunately, you get about 10% reasonable answers, the rest is ignorance, prejudices, silly comments, and sarcasm, all very helpful when you ask a serious question.
The statement "You are quite clever" can only serve as provocation. Why do people do that? Is it necessary? Does it give a better feeling?

So I accept the draft issue, but the ineffectiveness compared to air-water-air heat pumps doesn’t make sense to me. In principle, the outdoor units are the same, only the indoor unit either heats the air directly or heats water (and then the air via radiators). From gut feeling, I would say the former is more effective since you don’t have to first heat water to about 40 degrees to warm the air, but do it directly. But usually reality is different.
There are now devices that are very, very quiet and have intelligent control, almost sensing when people are nearby and adjusting the airflow accordingly (at least that’s what I have read).

The statement that you'd then have many devices outside that would need servicing is also not correct. I would only need two devices. One air conditioner is already on the roof and will stay there anyway. For all other rooms, a multisplit device would suffice. This would be similar to an air-water-air heat pump. The advantage for me would only be that I can position the air conditioning unit better than the device for the basement.

I accept the draught argument, but I don’t understand the ineffectiveness compared to air-to-water-to-air heat pumps.

Maybe we should simply list the disadvantages and advantages of an air conditioning system (high-quality split system) used as heating compared to heat pumps/floor heating:

Pros:
- High efficiency
- Can cool in summer
- Costs
- Ideal for smaller rooms
- Fast response time

Cons
- Not designed for very cold winter temperatures
- Due to technology, increased draught with classic indoor unit setup (system has to blow more to get the warm air from the ceiling to the floor)
- Noise (not high, but still loud compared to classic floor heating)
- No domestic hot water, so additional costs arise
- One indoor unit is usually not enough for larger rooms
- Different heat than floor heating (always cold floors and draught, see above) – floor heating is generally perceived as much more comfortable
- Higher heating temperature required (unlike floor heating, where the screed serves as a buffer/storage)

To what extent the air conditioner automatically works well controlled by outdoor temperature, I cannot say due to lack of experience.

Maybe we should simply list the disadvantages and advantages of an air conditioner (high-quality split system) as heating compared to heat pump/floor heating: Contra - Not designed for low winter temperatures - Different warmth than floor heating (always cold floor and draft, see above) - Usually a higher heating temperature is necessary (as opposed to floor heating, where the screed acts as a buffer/storage)

As far as I know, there are also air conditioners that can handle -15 or even -20 degrees. This is not different for air-water heat pumps to my knowledge (correct me if I’m wrong). Of course, floor heating is always better due to the surface area, but unfortunately not an option for me.

Okay, that helps me. I will now compare the things. Fortunately, I still have a functioning heating system. When it gets cold, I will try lowering the flow temperature to 40 degrees and see if the place warms up. Since I have an air conditioner in the attic, I will disconnect the heating there as a test and try heating with the air conditioner. Then I hopefully will have the offers for the air-water heat pump and the photovoltaic systems and will see from there.

The statements "You are quite clever" can only serve provocation. Why do people do that? Is it necessary? Is there a better feeling?

Your answer is great, but the assumption that this was provocation is misinterpreted. I really wanted to express that he is clever, so a compliment.

I'm curious how the heating in our single-family house will work with the split air conditioning. It didn't bother me in the office.

At -15 degrees I will turn on the gas heating :) because the split air conditioning is only designed for an operating temperature from -15 degrees to +46 degrees.

Your answer is great, but the assumption that this was a provocation is misinterpreted. I really wanted to express that he is clever, so a compliment.

Then thanks for the compliment. I will then no longer have a gas heating system, so if at all, the air conditioning must also run at low temperatures. I am still considering a stove for this case, but my household government is hesitating a bit :-)