Modulating heat pumps / spread / too many starts

A modulating heat pump can adjust its kW output to the demand.

With my modulating heat pump, you can set the spread, i.e., the difference between the flow temperature and the return temperature.

Is that the parameter by which the power is controlled? That is, adjusting the kW output so that a certain value is reached for the spread?

What changes if I change the set value from 5° to 2.5° or to 8°?

If I have the problem that the heating turns off too quickly and causes too many starts – even though all the individual room thermostats are open and the heating curve has been minimized – can I positively influence the situation by adjusting the value DTheizen (spread)?

The main problem is likely that the system was oversized, 3-12 kW modulating with a 6.3 kW heating demand.

Other points should also be checked or tried:
- Check and, if necessary, clean the dirt trap in the heating circuit/brine circuit
- Check the temperature sensors (flow/return)
- Check the bypass valve (possibly open too far?)
- Optimize the hydraulic balancing (significantly less heat reaches the upper floor than the ground floor when all individual room controllers are open)
- Limit the heat pump output to 3-6 kW or 3-9 kW

A modulating heat pump can adjust its kW number to the demand.

Does the flow rate also adjust automatically? A small temperature difference can lead to a high flow rate (because the heat pump simply cannot get rid of the heat - or it cycles). A large temperature difference leads to a low flow rate.

I currently understand it like this:

If I increase the target differential, the kW number is reduced so that the flow through the underfloor heating is slower, the heating water cools down more, and a larger differential results.

That would be an advantage in my case because the problem is that the heating produces too many kW of heat, which the house cannot absorb that quickly. I can force the heating to run at lower kW numbers.

Right?

Does the flow rate also adjust automatically? Small temperature difference can lead to high flow rate (because the heat pump simply cannot get rid of the heat - or it cycles). Large temperature difference leads to low flow rate.

Unfortunately, I don't know that. My guess was that the flow rate is controlled so that the desired temperature difference is achieved. But that is just a guess.

Is the flow rate proportional to the kW rating, or does it operate independently?

Is the flow rate proportional to the kW rating or does that run independently?

I actually can’t tell you that. I simply don’t know. Probably different from pump to pump – mine regulates the interaction completely automatically.