Firstly, Melcloud isn't great at controlling the Ecodan.

I don't know where the -39 comes from but you can set where the room temperature is monitored from the initial settings menu on the main FTC control panel.The source of the temperature is the main wired control, a remote thermistor wired into the FTC or the Mitsubishi wireless controller.  It will not show the temperature from a third party thermostat.

When curve is activated, you are right it won't respond to a change in room temp because you are not in room temp mode. The only way I've found to control the heating via the app is when you are in room temp mode. 

Where is your main FTC controller?  Is it in your living space?

As I said, the app isn't that good. 

You can change the flow temp and target room temp via the app, but not the WC curve or the offset. A bit frustrating for me as my installer put the FTC in the boiler cupboard, meaning it is useless as a thermostat/temp sensor for Room Temp targetting. My only option therefore if I want to control the indoor temp remotely is to not use WC and instead manually adjust the flow temperature.

Thanks for your valuable input regarding WC. That’s unfortunate.

Kev M, thanks for the tip regarding initial settings. I changed sensor to Main RC and now it’s +29C. It’s probably what it is inside the controller panel. Let’s see how useful of a reference number that will be. I guess there’s no way to move that sensor outside?

On another note, I’ve noticed once before and just saw again that the black flash icon was on, meaning the electric heater is activated. I wonder why it does that? It’s +2 outside and DHW is 50 degrees. House heating is on. It is quite windy outside but it looks a bit odd it would use electric heater now and did fine when it was -15 outside a few weeks ago.

Posted by: @marth

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Thanks for your valuable input regarding WC. That’s unfortunate.

Kev M, thanks for the tip regarding initial settings. I changed sensor to Main RC and now it’s +29C. It’s probably what it is inside the controller panel. Let’s see how useful of a reference number that will be. I guess there’s no way to move that sensor outside?

On another note, I’ve noticed once before and just saw again that the black flash icon was on, meaning the electric heater is activated. I wonder why it does that? It’s +2 outside and DHW is 50 degrees. House heating is on. It is quite windy outside but it looks a bit odd it would use electric heater now and did fine when it was -15 outside a few weeks ago.

 

The temp sensor is inside the main FTC control panel (the one you use to change settings).  You can move that panel depending on how long the cable is.  Alternatively you can attach a remote thermistor pac-se41ts-e to the main FTC box.  It comes with a very long cable.  You can get them for about £20 on ebay. That's what I use and it works well. Once it's attached another option appears in the initial settings menus you've already used. 

I don't know why the electric heater is on. Maybe a legionella purge?

@scrchngwsl I am on the weather compensation setting but I can’t understand why Melcloud does not give me any flow temperatures.  Temperature reports include a flow temperature feature but this I’d greyed out

@dotty9943 tap on the greyed out flow temp.  What happens?

Posted by: @dotty9943

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@scrchngwsl I am on the weather compensation setting but I can’t understand why Melcloud does not give me any flow temperatures.  Temperature reports include a flow temperature feature but this I’d greyed out

I assume you have tried tapping on the greyed out options?  If they are available, doing this un-greys them.

-39C means that the software running the FTC is a buggy version that needs to be updated. There is a firmware check in the MelCloud app, I presume this is the software that needs to be updated (mine was changed during an engineer visit), there's only one way to find out! When you switch to room mode the FTC will be using this incorrect temperature as a gauge of how much energy it needs to put in, this will be massively wrong, which is what might be triggering the back-up heaters to come on . You don't want to be in room mode until you have an accurate temperature showing.

@kev-m you are a star!  I have been struggling with this for days.  With your tip I have got it to work at last

Oh @kev-m you star you 😘🤣

@dotty9943 I’m glad you’re on the up 👍

@kev-m Now that you have solved the problem of temperature readings, this has enabled me to move on to the next stage of my attempts to find out why my heat pump is achieving such poor COP scores (They are about 2.3 when the predicted score is 3.2 and better.  We have done the following without much progress

a. On the basis of the Ecodan recommendations following a heat loss study, we have up graded all our radiators

b. We have replaced doors and windows so that all our doors and windows are now double glazed

c. We have put new thicker insulation in our loft

c. We have put throttles in our chimneys

d. Our radiators were rebalanced last week

e. We have set weather compensation so that flow temperature is at the recommended level

f. The heat loss study confirmed that our 14 kw is big enough to heat our. House and compensate for the heat loss

G. The system was serviced in December, when the filters were cleaned.

My web researches don’t suggest any other explanation for poor efficiency so can any one come up with new ideas?  Failing that I don’t know what to do short of taking our heat pump out and starting again with an efficient combi boiler