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Mitsu Wireless Controller and MelCloud

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Air Source Heat Pumps (ASHPs)

Last Post by DavidAlgarve 7 months ago

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DavidAlgarve

(@davidalgarve)

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Topic starter 12/08/2025 3:43 pm

I have just had a PAR-WT60R Wireless controller fitted to an Ecodan Hydrobox and I would like to compare notes with someone who has a similar setup.

Firstly, the heating is switched off until 1st October, but MelCloud is showing "House Heating" as "Idle", whereas previous to the installation I think it stated "Stopped" or similar. Surely, it should only show "Idle" when in operating mode and having reached temperature?

(DHW is also showing "Idle" outside the timed operating period and I thought this also, previously showed "Stopped" only outside a timed period).

Secondly, the MelCloud "House heating" is currently showing "Room temperature" as 32C whereas the Wireless controller is showing a room temperature as 26C. I suspect the 32C temperature is being picked up from the thermocouple in the Hydrobox FTC6 which is located in an outside Pump Room. I seem to recall that I can change over the selected thermouple in the FTC6 menu, and would appreciate comments.

I haven't got round to looking at the menu yet, mainly because our outside temperature is currently 41C!

342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW

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Morgan

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12/08/2025 3:48 pm

Similarly, my CH is currently turned off, and Melcloud shows this.

Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.

2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.

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DavidAlgarve

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Topic starter 12/08/2025 4:10 pm

@morgan

Yes, "Prohibit" was the word for when switched/ timed off.

So, apparently, my Melcloud is currently wrong for heating and possibly for DHW, but I am not sure if your DHW is currently switched on.

This post was modified 7 months ago by DavidAlgarve

342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW

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Morgan

(@morgan)

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Posts: 698

13/08/2025 6:48 am

@davidalgarve My DHW is switched on.

Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.

2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.

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DavidAlgarve

(@davidalgarve)

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Posts: 224

Topic starter 13/08/2025 7:26 am

It would seem that I have a problem (at least one!) in that both my heating and DHW are showing "Idle" when they are effectively timed off and the should be showing "Prohibit"

342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW

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Morgan

(@morgan)

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Posts: 698

13/08/2025 10:45 am

@davidalgarve

If they are 'off' because of a timed schedule, and this is their time to be 'off', it might be that it is actually in its 'idle' mode. I don't know that for sure, but in my post above, my CH is turned off in the main controller as opposed to a schedule, hence 'prohibit. The DHW is turned on but is showing 'idle' due to the temp still being above the reheat temp.

It will only show 'prohibit' if turned OFF. Not TIMED to be off. So far as I am aware.

I don't have schedules set. It's either on or off 24/7 or in Holiday Mode.

This post was modified 7 months ago by Morgan

Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.

2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.

ReplyQuote

DavidAlgarve

(@davidalgarve)

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Topic starter 13/08/2025 3:04 pm

@morgan I am finding it hard to accept that the display should read "Idle" when either the heating or DHW is "OFF", because I am reasonably sure that it showed "Prohibit" for this condition before the wireless control was added. It would also mean that no difference is recognised between "Up to temperature" and "Switched off"

I am still hoping for advice on the second point i.e. the fact that MelCloud (32C) is not reading the temperature of the Wireless Controller in the lounge (26C) and as such it cannot control - see photos.

I feel certain that Melcloud is still displaying the Hydrobox temperature 32C, but cannot recall where this selection takes place in the menu.

342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW

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Abernyte

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Posts: 258

13/08/2025 4:05 pm

On the FTC5 I think this requires the dip switch on the control board switched to on when you plug in the external receiver. SW1-8 from memory. It then allows the external room thermostat to control the system.

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DavidAlgarve

(@davidalgarve)

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Topic starter 18/08/2025 8:32 am

Well it has now become obvious that the installation of the Wireless Controller is a complete washout.

Almost certainly, Melcloud is still seeing the Hydrobox temperature rather than the room temperature from the wireless controller.

More seriously, the heat pump is running at random times (often during expensive daytime tariff), totally disassociated with the schedule times set on the FTC6. This is mostly heating DHW, but on occasion has been trying to heat the house (when we are experiencing record ambient temperatures!) through towel rail etc, which do not have thermostats.

So a most unwelcome fight to unfold just to get back to where we were before they carried out the work.

342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW

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DavidAlgarve

(@davidalgarve)

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Posts: 224

Topic starter 24/08/2025 9:01 pm

Update: I have found that the contractor had changed one of the options to "Forced DHW", and this was probably part of the problem. Having switched this off, I am back to logical operation with Weather Compensation and early morning scheduled DHW.

I have not had any offers of support, but I wonder if someone could confirm my thoughts on the correct selection of thermistor for use with the wireless controller.

Operating with Weather Compensation (without any room thermostat), under "Room sensor setting", I have "Room RC1" (single zone) set to "Main Remote Controller". This meant that MelCloud read the temperature in the FT6 but it did nothing.

With the wireless controller in place, am I correct in assuming that, Room RC1 should be changed to read "TH1" and will therefore read the thermocouple in the PAR-WT60 wireless controller?

342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW

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RobS

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Posts: 128

25/08/2025 4:50 pm

Hi David

We have an FTC7 but the settings seem to be similar to an FTC6. Our room sensor settings are:

Zone sensor selection sets zone 1 to RC1

Zone 1 programme sets programme 1 to RC1 from 00:00 (i.e. all day).

Looking at the FTC6 manual I'd guess Room RC zone select should be zone 1 and the Sensor setting for Zone 1 should be RC1 and a time of 00:00.

Hope that helps!

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DavidAlgarve

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Posts: 224

Topic starter 26/08/2025 9:17 am

@robs Hi Rob,

I really appreciate your information, and this appears to me to be much clearer than that which is given in the manual under: "4 Customising your Settings for Your Home".

It seems that I was on the wrong track in suggesting TH1 and now recall that this is the thyrister in the FT6

However, just to be absolutely sure, before I attempt a second installation of the wireless remote, I am attaching photos of the 3 steps in making the settings. (Incidentally, I have left the "Time Zone" setting as was and this seems to be the same as yours, but I don't understand the significance of this in relation to sensors)

I would be grateful for your comments.

342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW

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