CM927 wiring to BRAND NEW Vailliant ecotec plus 831

[Pooly89]

Hi guys

I know this topic has been covered before but I just want to be 100% sure before I attempt wiring the stat to the boiler.

one of my customer has existing Honeywell CM927 wireless stat wired into his current boiler but I have quoted to install a new one which is going to be a new ecotec plus 831. I have seen people saying that you can simply remove the link from the 24v connector on the boiler and wire the 2 wires from the stat into there. is this correct? I am asking as I do not want to risk damaging the new boiler's electrics and both manuals are pretty obscure.

cheers

Pooly

 

[Ermintrude]

Opentherm switching is much better through the 24v terminal as it reduces wear on relays and lower voltage spikes. I always use 24v. Call valliant and they will say the same.

 

[southcoastboile]

If you are using 240v switching then do not connect to the 24v link as you can blow the pcb. I always use a delta dore l and n into the mains in and then use the 24v connection for 24v switching.

 

[stevetheplumber]

831s have no power out like the old ones so you only bring a switch live back to the 240 plug and remove the 24v link if using a 240v stat