Gary68

Agree with John sounds like its plumbed incorrectly and its not getting hot as its just pumping the return water from zone 1 that is already cool. If you ramp up the flow temp to 45C and the ufh start to get warm then that would confirm it.

Mine does that too, I think its just the app. Do you have a mitsubishi preplumbed cylinder, if it was for 2 zones there should be 4 pumps in total, 1 for the primary circuit, 1 for each zone and 1 for dhw. If you turn both stats on to call for heat you should have 2 pumps lit up with lights if they are the std grundfos pumps that are usually on the cylinder

Are you saying that you can only heat zone 1 or zone 2 at once, or is just that you haven't got the thermostats calling for heat at the same time? If its the former then something have been wired up incorrectly. I have UFH downstairs and rads upstairs they are on separate stats and both can call for heat independently or together they just have different pumps for each circuit.

If you unscrew all of the actuators I believe that should open all the circuits as the actuators hold them closed so if the actuators aren't wired in correctly or they fail, then they will just stay closed.

Just another point for reference, we have a not very well built or insulated 190sqm house from 2003, heat loss was calculated at 7kw and have an 8.5kw Ecodan and it was fine at -6C last winter.

What is calling for 'heat', you may find that you need to increase the temperatures on your thermostats to call for heat which will tell the heat pump to turn on and then cold water will circulate round the system. That's how it works with my air to water heat pump.

Its an Ecodan, flick DIP switch SW2-4 to on, reboot system, cooling now available in heating menu select flow temp and away to go.

Mine is set to 48C and I can just about hold my hand under it continuously, so it sounds like you are a lot lower than that if the bath is just warm enough, at 50C you get burnt in 5 mins. Also depends where the temperature sensor is in your tank if its not towards the bottom a lot of the tank won't be at 52C

The Melcloud app is easy to program, just choose your unit, go to timer, I add in the start of the off peak time and till it to run at a fixed flow during the winter. The flow temp can only be set from the main controller not the app. Then at the end of off peak I tell it to run change back to WC. In spring and autumn, I still run it at night but only in WC mode so 32C rather than 45C in winter. At this time of year it probably won't come on till the next off peak period, so no peak use.

Agree with Johnmo I have an ecodan I had an extra ufh pump fitted and a wiring centre with actuators and zoned thermostats. 5 years later it’s all redundant never needed in the first place all the actuators are disconnected all zones open all the time ufh pump is turned off water flows round quite happily when the heatpump is on. Probably £500 of waste if it was designed correctly in tne first place

£200-£300 is typical in southern England

3kw is exactly what most immersions pull that would my first check if you have one. The switch for ours is in the understairs cupboard and my in-laws turned ours by accident had me puzzled for a while.

For a rough estimates divide by 2900 so yours would be 6.3kw so your looking for a 7 or 8kw heat pump

If you have the MELCloud app you could do it. There is a timer function and you can set it to heat or cool at any time or day.

Post a screenshot of the front screen of your controller and your heat curve sounds like either the heat curve is wrong or you are running at a set temp and not weather comp