Sounds like it might be on room auto adapt mode. Could you take a pic of the FTC controller screen?

Posted by: @gfletcher

Hi All,

I have a Mitsubishi Ecodan, Mixergy and Tado set up but something isn't quite right with the heating. The Tado is calling for heat but the heatpump isn't providing. The FTC5 controller is in the same cupboard as the mixergy tank - so it is quite warm. I have managed to get the heatpump running by turning up the target temp on the FTC5 controller to 40degrees (instead of the 21degrees it was set to) because I wondered whether it was sensing a 'room' temp of higher than the target and therefore not coming on - but I am guessing! Any thoughts as to what might be happening? And then what I ought to do as a permanent fix?

Any help gratefully received.

Thanks,

Gavin

Hi Gavin,

Is yours a newly installed system and do you know if it has been configured for weather compensation control or with the addition of auto adaptation?

Have any changes been made recently?

@benseb

Thanks for the reply - here is a pic from the front screen. 

@derek-m 

Hi Derek, It is fairly new - but I only switched it on for heating the other day. It does use a compensation curve (I think) - the installer talked me through that bit. Auto adaptation - don't know.....

I did switch it off and back on again yesterday after the Mixergy had to have an update. But apart from that the heating has been off so not really been used in anger until the weather dipped recently. Not sure if that answers your questions.

@gfletcher so that pic shows you have it on a fixed flow temp. 40c is fairly high for this time of year so will be quite expensive. Sounds like you’ve turned that up?

you’ll probably be better on weather compensation mode. 

But either way that won’t be turning things off. The pause icon shows that either the heat pump is up to temp and doesn’t need to run, or the external room stat is not calling for heat. So it could be your Tado that’s causing the issue?

to be honest we had Tado and found it wasn’t very efficient.  We’ve removed ours now. It’s not great using third party on/off controllers. You’re better having a well tuned weather comp setup and leave it running all the time. 

@benseb 

Thanks for the reply. The problem was that the Tado was calling for heat and the controller was set at 21degrees. So I turned the controller up to 40degrees and the heatpump kicked in and was then responding to the Tado. I definitely want to be on weather compensation mode as I understand that means that the heatpump is working at a higher COP - but for some reason when the controller was set lower it wasn't responding to the Tado. 

Hold on. If it was set to 21 then it’s quite possible it turned off as the flow temp was met. 21 is very low (it’s not room temp) 

Look at YouTube on how to change it to weather comp. Personally I’d remove your Tado or set it to 25c so it’s always on. There’s a load of good videos in the Heat Geek YouTube channel on how to tune the weather comp. 

@benseb Thanks - I'll take a look. I was keen on the Tado system so I could change the temp of individual rooms. Even when I put the Tado onto 'boost all rooms' it was still not causing the heatpump to kick in.

So the heatpump controller was at 21degrees (not set by me, just what it was at when switched on) and weather comp curve is on the system. Maybe there is a setting that is wrong - I'll look through the Heatgeek videos and see if they shed any light,

Thanks

Gavin

Curve might be on the system but it isn't used in fixed flow temperature mode. Switch to curve mode. I'm not in front of my controller now, but I think it's menu, heating and then the left button cycles between fixed flow, curve and room modes. Or you can use melcloud if you have it. 

@mjr Thanks for that - I have now switched it over and the screen looks like this -

Do I need to do anything else e.g. with the +0degrees bit? Or is that just for if the heat output isn't enough.

The heating symbol is on pause - which is right because the Tado isn't calling for heat at the moment.

@gfletcher yes, I understand that just shifts the curve up and down, to help cope with those situations when you get more solar gain than usual or a cold wind whipping across.