Hi Donald, welcome to the forum!
I haven’t participated in this topic before, but I can give some insights to you as I have this same unit.
A key thing to know is that heat pumps do not have direct control of the flow temperature. They can only put heat into the system and adjust the amount of heat to reach the desired target. The compressor can modulate down to a minimum output level, which is around 5-6 kW for this unit. This is still a considerable amount of power going into the heating system, which needs to be dissipated by the radiators and other emitters. For this reason it’s advised to have all TRVs open to provide as large an emission surface as possible. Having multiple zones or mixing valves reduces the output of the circuit.
When the heat pump is running at it’s lowest output, but the flow temperature is still rising, that means not enough of that heat is being emitted into the house and returning back to the heat pump. The only option the heat pump then has is to turn off the compressor for a short time, resulting in cycling. This is quite a common state for any heat pump in mild weather, and 2-3 cycles per hour is perfectly acceptable.
The ideal state for a heat pump is to run continuously, producing exactly the right amount of heat to match the heat loss of the property for whatever the outdoor temperature is. This is what the weather compensation curve is meant to do. However, many installers will overestimate the heat loss, fitting a heat pump that is way larger than necessary and that cannot modulate low enough. My own property needs only 5-6 kW at -3°C, so the 11.2 kW unit I have is way oversized.
The Ecodan is pretty bad for cycling in weather compensation mode. Anecdotally, many users find they get much better performance when using auto adapt mode with the remote room controller.
Some other topics that may be useful:
- How to reduce cycling?
- Heat pump demand cycling vs compressor load cycling?
- My heat pump is too big, what should I do?
- Weather Compensation FTC5
- Calculating the optimal weather compensation curve
If you’d like advice about your own heatpump, I suggest starting a new topic describing the setup of your system (rads, ufh, zones, buffers, etc) and hopefully you’ll get some useful answers there.
The first step to understanding your heat pump is good monitoring; MelCloud interface is awful for that, so I provide a service that pulls that data into Emoncms - message me if your interested.
Hope that helps.