Heatmiser UH4 with 2 Tado wired thermostats always calling for heat

Recently we had (wet) UFH installed. This is a retrofit along side the original radiators which are mostly controlled via Tado TRVs, these work great.

A new Heatmiser wiring centre (UH4) was installed to control the 2 UFH zones, which is wired into the Tado Wireless Extension Kit.

We have two Tado smart thermostats that are wired back to the wiring centre using just the “COM” and “NO” ports these go to the “L” and “SL” respectively in the wiring centre.

The problem I have is that if the Tado thermostats are attached to their wall plate they will call for heat, no matter if the thermostat is set to “off” or “25”. If I pull the Tado thermostats off of their wall plate, therefore breaking the connections back to the wiring centre, it stops calling for heat and the boiler shuts down.

This leads me to think the wiring centre is wired correctly, and the Tado’s are not switching their relays off/on properly. As the wiring centre is able to call for heat and stop calling for heat.

Also worth noting, I’m using the battery power on the Tado thermostats, not the 230v that COULD I suppose be supplied from the Heatmiser wiring centre.