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Pair Mitsubishi Ecodan with Heatmiser Neostat

  • October 14, 2025
  • 3 replies
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I’m hoping somebody can help me as I feel like I’ve tried everything!

 

I recently moved into a house with a Mitsubishi Ecodan Heatpump and heatmiser neostat thermostats. Downstairs there is underfloor heating which is working perfectly with the thermostats. However, there are radiators upstairs which are also supposed to be controlled by a single neostat, but this seems to have lost connection to the Ecodan. Does anybody know how I go about re-pairing the neostat to the ecodan so that it can control the radiators? It looks like there is 2 zones on the ecodan system - one for upstairs and one for downstairs.

 

Any help would be very much appreciated!

Best answer by M.isterW

I can't help with pairing the neostat to your FTC but I can tell you that Ecodans don't play nicely with third party controllers. You're better off using Mitsubishi remote controllers. They will allow you to run the system in auto Adapt mode which will improve your efficiency... and save you money.

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juliamc
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  • juliamcCarbon Catcher***
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  • October 14, 2025

​@M.isterW ​@Ecodanwarrior ?

Chris_OVO
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M.isterW
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  • M.isterWCarbon Catcher***
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  • October 14, 2025

I can't help with pairing the neostat to your FTC but I can tell you that Ecodans don't play nicely with third party controllers. You're better off using Mitsubishi remote controllers. They will allow you to run the system in auto Adapt mode which will improve your efficiency... and save you money.

1992 4 bed detached house. Solar PV + battery, Zappi EV charger, Mitsubishi Ecodan ASHP and i-life2 fan assisted radiators.... No gas 😊
juliamc
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  • Ben_OVO
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  • October 15, 2025

​@Nelertron1906 good morning and welcome to the OVO Forum. I’ve added the Heat Pump badge to your account so that other members can recognise you.

 

Apologies, but I’m not sure myself on this one. Thanks for your help here as always ​@juliamc and ​@M.isterW.

 

​@Nelertron1906 I’ve been having a look at some other Forums and can see people reporting similar issues, for example:

 

I installed the same Heatmiser UH8 UFH system in my current property but used a specialist supplier to install the Mitsubishi Ecodan ASHP under the government grant scheme.  I soon started getting L9 (insufficient flow) errors on the Ecodan and on checking, the ASHP engineer had completely ignored the Heatmiser controller - nothing was connected to the heat call terminal block.  So, if one of the UFH zones called for heat, nothing would happen unless the Ecodan was also calling for heat, and if the other way around, ie. the Ecodan called for heat but no UFH zones were calling for heat, the Ecodan would shut down with an L9 error.  When questioned, the ASHP company told me that was the only way that they could install it and the Heatmiser controller was my problem! I now run the system with the Ecodan remote adjacent to the hall UFH thermostat and keep those set at the same temperature, but I also keep another UFH zone (the coldest zone in the house) permanently open (by leaving that zone's actuator off the valve).  This has been okay as a workaround.

 

The full thread, and answers on the buildhub forum can be found here: https://forum.buildhub.org.uk/topic/24544-mitsubishi-ecodanftc5-and-heatmiser-uh8-ufh-control/

 

If it’s a rental property I’d recommend speaking to the Landlord about this, as it needs to be sorted before the winter. 

 

Let us know how you get on!

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