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My Mitsubishi ASHP was installed last year, to run the existing radiator CH system.  An extension with UFH was about to be built and the installers left me with a separate pumped connection for the UFH.  That has duly been completed and connected and been running by connecting the UFH pump in parallel with the existing CH pump - ie I have one zone.

I now want to separate the CH and UFH into separate zones.  I have the contacts from the UFH wiring centre connected to IN6 (Room Thermostat 2 input) and the UFH Pump to OUT3 (Zone 2 space heating).

I have turned on DIP switches SW2-6 and SW2-7 but keep getting an L5 error (Indoor FTC temperature thermistor reading incorrect value, thermistor disconnected or wired into the wrong connection on the board, incorrect dip switch setting on the FTC board).  The manual tells me I don’t need an indoor thermistor if I’m using the remote wireless controller.  I have also tried changing SW3-1 and SW4-1 but still get an error code.

With SW2-6 and SW2-7 on, the controller shows 2 zones under the Heat Pump symbol but then goes into the error mode.

What am I doing wrong?  Any help much appreciated.

Updated on 07/10/24 by Shads_OVO

You could try asking this on Facebook’s Mitsubishi Ecodan Help group or on the https://renewableheatinghub.co.uk/forums/renewable-heating-air-source-heap-pumps-ashps

Those sites are visited by installers so I expect you’ll get a useful response.

Thanks for that response - I’ll try posting there.

Hi @BryanB,

 

It seems that @juliamc has given some really good advice advice here. If you get a response it would be helpful if you’re able to pop back to us, as your update could be helpful to other community members. I’ve also given you a heat pump badge on your profile as you’ve mentioned having one. 🙂

Hey @BryanB,

 

Did you get a response when you posted on Facebook?

I had some good advice from the renewableheating hub forum.  It seems there are lots of errors in the installation manual, especially regarding the DIP switch settings.

SW2-7 should be the only DIP switch I need to turn on, but with SW2-7 ON it gives me a flashing LL error at the top of the main controller, but it still appears to run normally. However it does not seem to set up a Zone 2.  The bottom left button on the controller is still marked "I" and I cannot set up Zone 2 room sensors.  If I turn on SW2-6 I don't get the LL error and can set up Zone 2 settings - left button on controller marked as "Z1 or Z2".  But then after several minutes the L5 error comes up and everything shuts down.

I guess if I turn on SW2-6, it's looking for a mixing tank(which I don't have) but presumably would have a thermistor which it can't find, hence the L5 error.  I have what I think is called a low loss header, but that's hardly a mixing tank, with no temp sensors.

So not a lot further on…..

Hi @BryanB,

 

I’m sorry to hear that you’ve been unable to resolve this.

 

It’s good to hear that you were still able to get some useful information from the renewableheating hub forum. I’m assuming you didn’t get anything of much use from the Facebook’s Mitsubishi Ecodan Help group?

 

I really hope you’re able to get this sorted soon. Please keep us updated.

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