Updated on 04/03/25 by Ben_OVO
My system is a Daikin so I don’t have experience on Ecodan controls, but here’s a couple of things to check:
All your radiator valves should be open fully to ensure the water flows unimpeded, similarly the underfloor (though I have no experience with those either !).
I don’t know if there a ‘quiet mode’ on the Ecodan. It might be worth trying the upstairs a degree cooler and then not doing the setback, but setting it to quiet at bedtime. Having a setback means it’s got to work hard to restart everything in the coldest part of the night to get it all going for the morning. I have my heating on all night now which took some getting used to, but the bedroom radiator is sized to keep the room at 18 degrees and we have the window open so it is cool enough in there!
When it does the water heating the outdoor unit will be noisiest, as it’s working hardest then. If you can do that in the warmer part of the day it should use less energy. Do you need to heat it twice a day ? Do you find you run out of hot water if it’s only heated once ?
For comparison I have a 3 bed bungalow with 8 radiators and the heating at 22 degrees (soft southerner). Our cylinder is 210 litres, 2 showers per day, water heated to 49. On 10th Jan when outside temp was around -0.5 deg it used 38 kWh. Last week on a day around 3.0 deg it used 27 kWh.
@M.isterW knows all about the ecodan’s auto control !!
It looks like you've got third part controls (i.e. not Mitsubishi's own controls) and that's not a good thing. If you've set the system to weather compensation, on the Mitsubishi FTC controller, then it should run without a third party thermostat turning it on and off.
Can I suggest you find the Mitsubishi Ecodan group on Facebook and ask them for help. There are people far more knowledgeable than me in the group. They will want to see pictures of all of your controls (FTC, thermostats etc).
https://m.facebook.com/groups/674120483503581/
