What is most efficient way to run heating for my Mitsubishi Ecodan Air Source Heat Pump?

It sounds like there may be an opportunity to turn down your flow temperature if you feel your flat is getting too warm if you need to override the thermostat.

Do you use a ‘weather compensation’ setting that adjusts the water flow temperature based on the outside temperature? You may be able to reduce the settings so that the pump is only having to heat the water to a lower temperature. This may mean the flat takes slightly longer to warm but should be more efficient. I try to stop my heat pump having to cycle on and off by doing this. The aim being so that it only just manages to reach my desired room temperature  - the room thermostat being used as an override to stop it getting too hot.

you may want to look on YouTube at the range of consumer focused vids by Heat Geek. They will teach you how to refine your system to be most efficient and comfortable - I have done this and it has made a difference.

As others have said, low and slow using weather compensation is the way forward with heat pumps.

what temperature is your hot water set to ? It doesn’t need to be more that about 45degC (but needs a 60degC heat up once a week to avoid legionella).

I have an ecodan and would agree with the above posters’ comments. I have found that about ¼ of my electricity is for hot water, and ¾ for heating. So getting the heating right will save you the most money.

For hot water I changed 2 settings: the temperature that the system heats my water to is set to 49C, also i turned off the automatic heating so it just heats the tank up very early morning and evening.

For heating you probably want the thermostat set to the temperature you find comfortable (eg 20C) and leave it at that (or maybe switch down just a bit overnight eg to 18C). It takes a long time for heatpumps to change the temperature in your home, so its actually better to keep it at the same temp all the time. You want the heat pump set to weather compensation mode. This means that your radiators will get warmer when its very cold outside, and just slightly warm when it is mild outside. 

Changing these settings on the ecodan control panel isn’t very obvious so best to google it and watch a video of someone doing it