Quick sanity check before I wire in a thermostat..

[pauldoubleyou]

New home owner here.

I have quite an old boiler, it is an Alpha CB24x. It has no thermostat, instead having a Drayton basic control box. It has no timer settings, simply a 'twice' function that isnt working out that useful.

Anyway, I bought a combined control unit and thermostat that works by RF, here:

https://www.amazon.co.uk/Salus-RT300RF-Radio-Frequency-Thermostat/dp/B003EQ8FMC

I'm happy wiring it in by the wiring diagrams, and am also happy that it has 230v switching. However should this unit completely replace the old Drayton unit?

Or do i leave the old Drayton unit in place, in the 'on' function, and wire the new RF one in as a simple thermostat to the external control terminals on the boiler?

Thanks in advance for any replies.

 

[omega015]

The Salus should replace the Drayton completely, so there's no need for it to be connected.

 

[pauldoubleyou]

Thanks for the reply. I dont want to use the location of the Drayton for the Salus as its not ideal for a thermostat (near the oven) so that works out well. Just need to make sense of the wiring coming from the drayton - are those wires 240v too? There seems to be four wires going to it.

 

[omega015]

Looking at the boiler wiring diagram there's live, neutral and then 2 wires for heating, they go into COM + NO and may be at mains voltage too. This was the manual I was looking at (make sure its for your boiler though) http://www.alpha-innovation.co.uk/custom/upload/instructions/Old models/CB24 28 Installation and Servicing Inst.pdf
Also note that taking off some boiler covers is not allowed by non gas safe registered persons, but your boiler looks like you can get to the electrical connections without accessing the sealed chamber.

 

[pauldoubleyou]

I think ill simply unwire the drayton completely and fit the Salus to the recommended T1+T2 in the installation guidelines (that basically look like the usual thermostat connections). The timer and controls on the Salus will then just activate the thermostat I presume.

Is there any detriment to the boiler being controlled solely through the thermostat 'external control' terminals all the time? It would be using 230v switching to turn the heating off and on all the time instead of however the drayton is wired in. With the age of it im worried it will knacker the PCB.

You are correct - the electrical side is behind the clock / controls cover and can be accessed by flipping the panel down.

 

[pauldoubleyou]

Looks like i totally got confused as to the wiring of the thermostat / control unit.

I'm going to replace the Drayton with the receiver from the Salus and go from there. Thanks for the info.

 

[pauldoubleyou]

Done, fitted, works perfectly. Thanks for the advice.