@boycey If I remember correctly, when the engineer fitted the replacement thermostat, the cable wasn't very long.

Yes, my thermostat is in the same position as yours; on the back, top right from the front.

As Mitsubishi are going to send an engineer, I don't think I should try repositioning at this stage.

Thinking about this a bit more, the excess reading is when it's sunny but the thermostat, being behind the pump, is not necessarily in the sun. It is for a while though when the sun is low at this time of year.

My original thought was that it was reflected heat from the house brickwork behind the pump. You can really feel the heat from the brickwork in the summer.

It's currently 39cm from the back wall so well within the 30cm that mitsubishi specify.

Posted by: @richard24738

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As Mitsubishi are going to send an engineer, I don't think I should try repositioning at this stage.

Thats good news

Posted by: @richard24738

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My original thought was that it was reflected heat from the house brickwork behind the pump. You can really feel the heat from the brickwork in the summer.

It's currently 39cm from the back wall so well within the 30cm that mitsubishi specify.

Hopefully your obs today will clarify whats going on so you can tell the Mitsi engineer! 

The reflected heat from my south facing white wall has definitely not subsided 30cm from the wall.  

Silly design, which obviously they know as they modified it for the R290

@jamespa Extending the cable is not something I would like to attempt especially as Mitsi have agreed to send an engineer. Perhaps he will do it.

It's quite sunny now but cold. If the temperature rises, I'll try shading the unit.

13:51 - Pump is "idle"

Temperature in the shade at the side of the house 14c.

Outdoor temperature reading of the heat pump 21c.

The top of the pump is shaded with an umbrella.

I have placed a normal thermometer on the back of the heat pump at the top and it reads 21c so that means the Mitsi outdoor thermostat is reading correctly.

Placing my thermostat near the bottom of the heat pump close to the cooler side of the house reads 18c.

Unfortunately, it looks like a sun and shade issue.

@jamespa: you mention a change on the R290. I can't find any documentation. Do they now do wifi remote or is it simply a positional change?

Posted by: @richard24738

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@jamespa: you mention a change on the R290. I can't find any documentation. Do they now do wifi remote or is it simply a positional change?

It wasnt me that mentioned this, was someone else, I was only repeating what appeared to be a very plausible statement.

Posted by: @richard24738

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Unfortunately, it looks like a sun and shade issue.

Yup.  Well at least you can tell the Mitsubishi engineer what problem he has to fix.  He may of course simply turn up with a sensor on a longer wire.

@jamespa Well, I am not alone. Someone on the "Heat Geeks Heating Help For Home Owners" Facebook forum has posted exactly the same problem.

Sounds like a thermostat and a long wire will be the solution. Shame they don't do a wifi solution. It would make positioning so much easier.

@richard24738 just add a length of wire to exsistng one? Would that work, I think it's just transferring the signal from the end sensor. Might be worth a try, can always reconnect without the extra bit of wire if it doesn't work. Until you get another longer one

@boycey Think I'll wait to see what Misti come up with.
It would be nice to hear from someone who has relocated the Ecodan thermostat. Hopefully someone will see this.

Posted by: @richard24738

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@boycey Think I'll wait to see what Misti come up with.
It would be nice to hear from someone who has relocated the Ecodan thermostat. Hopefully someone will see this.

Hi @richard24738 

we weren’t happy with our FTC Controller being installed in our cylinder cupboard.

The ftc controller is supplied with a single 10 metre cable. I just asked my installer that, since they normally fit short cables they must have loads of full length cables left over from all the installations. So they gave me an unused stock length. 
I routed the 2 core cable to where I wanted it and the installer came back and made the connections. Just 2 bare cable connections at each end. No plugs. Presumably a longer cable could be fitted but we were able to use the supplied cable length.

hope that helps.

By getting the installer to make the connections it ensured there wasn’t any issue with warranty.