How to bypass / remove EPH 2-zone controller

Waesfjord

Looking for some help as my EPH R27 Series 2-zone controller is faulty. I no longer use its timer functionality as have already upgraded a couple of years ago to Nest controllers and thermostats. So EPH controller left always on (i.e. bypassed), which has worked fine till recently.

Issue on one zone only, where the heating has failed to come on. I've ruled out the motorised valve, Nest devices by trial and error.

I've cycled power to controller, hit master reset (does nothing, though manual states I should have to reset date etc), also noted the dimming of buttons as I toggle the zone on to off etc, so guessing the circuit board is intermittently faulty.

Attached is the wiring schematic from EPH datasheet, also a matching photo of the house wiring behind controller.

Million dollar question - is there a simple way to reorient the live and neutral wiring on terminal block so that the wiring loop is always closed on zones wired on terminals 3 and 4, leaving Nest thermostat only to control zonal heating? I can then leave the controller attached to the wall (unpowered) to cover the terminal block for safety reasons only.

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bucurb

I'm in the same boat. Based on the wiring diagram I'd guess all you have to do is move the wire from 3 to 1 and from 4 to 2, so the circuits are always closed. But have not tried that yet, maybe get an electrician to chime in.

Wearb

I didn't answer the op because I didn't have a good handle on his total wiring setup and didn't want to make a suggestion that could damage their equipment.

What you suggested is probably correct, but it's an odd way to switch to a smart system. When installing a smart thermostat and leaving the original programmer in place, I'd wire it so that the programmer is normally off and only used if there was some failure with the smart system.