Drayton wiser to electromax boiler

JoeBowtell · Nov 11, 2022

Hi.
We are looking at installing a Wiser smart heating system inc. trvs
We are currently electric only, with normal rads and a Heatrae sadia electromax combi boiler doing hot water and central heating duties.
Control is via a danfoss tp5000 battery programmable thermostat. This is only a two wire unit. No industry standard back plate so I know I need to wire a backplate for the wiser.
Looking at the wiring diagrams for the boiler and wiser system I believe I need to run a live and neutral from the boiler to the wiser. Is this 240… seems excessive if so, but where best to pick it up, 24 hour on (on boiler) perhaps. Then feeds to HW on and CH on on the wiser backplate. Are these simply reusing the room stat L and room stat R feeds that are currently used for the switching by the tp5000?
Thanks for any thoughts in advance!

davesparks · Nov 11, 2022

A combi boiler doesn't require any hot water signal from the wiser controls as it operates on-demand.

davesparks · Nov 11, 2022

It looks like you need the single channel version of the wiser control, this will need a permanent mains supply and its switched output connected to the heating L and R of the boiler.

JoeBowtell · Nov 11, 2022

Ah interesting. Assuming then that the hot water heats as required solely on the off peak feed unless the boost button is pressed then on 24 hour. Think I was confused by the diagram for the room stat L and R as one appears to go to the CH switch one to the HW switch

JoeBowtell · Nov 11, 2022

So second look without being an idiot… on the single zone wiser backplate terminal N and L to boiler N and L (pick up from main boiler supply or 24 Hour N and L?) terminal 1 to Room stat L on boiler and Terminal 3 to Room stat R on boiler? Then hopefully job jobbed?
Thanks

UNG · Nov 11, 2022

JoeBowtell said:
So second look without being an idiot… on the single zone wiser backplate terminal N and L to boiler N and L (pick up from main boiler supply or 24 Hour N and L?) terminal 1 to Room stat L on boiler and Terminal 3 to Room stat R on boiler? Then hopefully job jobbed?
Thanks

Yes that is the way to do it

JoeBowtell · Nov 11, 2022

Perfect thanks for reminding me I wasn’t paying attention!
Any preference on where to pick up the N and L? The 24 Hour terminals on the boiler are easier from a wiring perspective than the main boiler L and N being in the same block as the room stat terminals