Wiser heating wiring.

[Apneajoe]

Hi all,
Just a quick sense check if I can. I have a Heatrae sadia electromax with a tp5000 two wired programmable room thermostat. Im looking at the potential of moving to a wiser smart system and specifically wiring the wiser hub.
Am I correct in thinking I need to run new wire to connect ‘room stat L’ on my boiler to terminal 4 on the wiser backplate, ‘room stat R’ to terminal 3 and also a wire to boiler neutral and boiler permanent live (N and L on the wiser backplate)?
Any suggestions as to which N and L on the boiler end?
Currently boiler works as expected and is wired matching the wiring diagram.
Wiring diagrams attached below.
Thanks in advance

 

[ericmark]

Much depends on how the system is already wired, I have never really worked out why anyone uses an electric boiler? I will guess in some way linked to off peak power, but with gas or oil to have a heater in each room would mean multiple flues, although I have seen this done, having one central boiler is often a cheaper install, even when one factors in the price of TRV heads, by-pass valves, and all the other equipment needed to allow individual room control.

Wiser wall thermostats come as three versions, with one to three zones, electric boilers will be simple on/off, but I have no idea of current involved, and if direct or using a zone valve which acts as a relay.

The main advantage of the Wiser system is the way the TRV's work, using algorithms to work out how long it takes to heat the room, so the user simply sets the time he wants the room to a set temperature and the system works out the rest, and the wall thermostat is more like a hub, collecting information from the TRV's.

However not sure how this will all work with an electric boiler? I just stayed in a Travel lodge and they simply had an electric heater with a digital control panel in each room. Only with a heat pump does a central heating device make sense with electric.

 

[Apneajoe]

Electric boiler as we have no gas mains in the village, and no space for tanks. System used to be on storage heaters but has long since been replaced with radiators. The system all works fine if more expensive than ideal. The wiser system will definitely work with the boiler etc and the trvs will allow us to manage the heating better. Currently we have issues with some rooms being too hot some too cold and aside from running round manually adjusting trvs to suit while heating is on have never found a happy medium.
Wiser helpfully/unhelpfully have confirmed the system will work on our boiler but won’t comment on specific wiring for my situation. Understandable of course.
Just hoping for someone to check my working on the wiring diagrams to confirm if what I think is correct is actually correct!

 

[oldbutnotdead]

You need permanent N and L to supply the Wiser hub so connect N to the 24 hr N- see later for L.
It appears (from diagram) that Room Stat L goes live when CH ON is selected on that box of tricks, and connecting Room Stat L to Room Stat R will call for heat. Be worth checking that theory out with your multimeter...provided above is true
I'd suggest that you connect Room Stat L to L on the Wiser hub and Room Stat R to CH ON on the Wiser hub. Then leave CH ON on your existing box & control with the Wiser.

 

[Apneajoe]

Thanks for that. Makes sense I’ll break out the multimeter and check ideally I’d like to remove and replace the existing box entirely it’s in the spot I want the hub, and it’s temperamental at the best of times. From my reading room stat L is the central heating switch and room stat R is the hot water so might have to be separated?

 

[oldbutnotdead]

Thanks for that. Makes sense I’ll break out the multimeter and check ideally I’d like to remove and replace the existing box entirely it’s in the spot I want the hub, and it’s temperamental at the best of times. From my reading room stat L is the central heating switch and room stat R is the hot water so might have to be separated?

DHW is completely separate on that wiring diagram. It would be unwise to assume that the dhw control circuit is 240v- it probably is but again measurement is key. Because the Wiser doesn't have volt free contacts I'd suggest using a relay if you do want app control of the dhw- you'll need to delve inside that box as well.
That box is (or should be) ensuring that you are using cheap (off-peak) energy when it's available, as well as a few other jobs so best hanging onto it.
Presumably that box has a front to it? Fix the hub to the front of it.

 

[Apneajoe]

The current box is a Drayton tp5000 simple two wire programmable timer/room thermostat it feeds back to room stat L and room stat R battery powered so definitely not 240. No standard back plate on it and no other boxes just direct back to boiler panel as per the boiler schematic

 

[oldbutnotdead]

Ah, misunderstanding. Yes you can ditch the tp5000. But be very clear here- just because the tp5000 is battery powered does not mean the the terminals it is connected to are not at 240v. In fact that circuit diagram clearly shows that Room Stat L is internally connected to 24hr Live
EDIT That circuit diagram- is that actually the boiler internals or is it an external controller linked to the boiler?