Cylinder Themostat Wiring?

[DIYBlues]

Hi

I've just changed my copper hot water cylinder and purchased a new themostat. (Honeywell L641A Cylinder Thermostat). The original one was a Switchmaster which had 4 wires Black, Blue. Brown and Green/Yellow

On installing the new themostat it only has C, 1 and 2 but dosn't need an earth. The instructions say terminal 2 is used when used on Honeywell Y-plan systems???

Unfortunatley I didn't think to note down the old wiring locations but looking at photos online for the same unit Black is in 1, Blue is in 2, Brown is in the middle (i'm guessing this is C) and Earth is Earth.

Can anyone give me some advice for connecting up the new thermostat is it the same as the old Switchmaster inc 2 (the y-plan system) excluding the earth wire?

Thanks in advance DIYBlues

 

[Guest123]

So, is it a y plan system you are working on??

 

[sedgy34]

try
c= brown
1=black
put blue in a crimp/connector as it may become live (depends where other end is connected)

 

[Edd]

Drop the cover off the joint box, find the 3 port valve wiring, "if its a Y plan" then two of the stat conections will go to the valve. that in your case will be 1 and 2.
1 will go to orange, 2 will go to grey,, the third will come from the programmer and go into common..

 

[sedgy34]

So, is it a y plan system you are working on??

Lenny hes DIY he probably wont know that

 

[Megavolt]

Hi

I've just changed my copper hot water cylinder and purchased a new themostat. (Honeywell L641A Cylinder Thermostat). The original one was a Switchmaster which had 4 wires Black, Blue. Brown and Green/Yellow

On installing the new themostat it only has C, 1 and 2 but dosn't need an earth. The instructions say terminal 2 is used when used on Honeywell Y-plan systems???

Unfortunatley I didn't think to note down the old wiring locations but looking at photos online for the same unit Black is in 1, Blue is in 2, Brown is in the middle (i'm guessing this is C) and Earth is Earth.

Can anyone give me some advice for connecting up the new thermostat is it the same as the old Switchmaster inc 2 (the y-plan system) excluding the earth wire?

Thanks in advance DIYBlues

Call a sparky as it really needs testing to confirm which wire is which and the redundant ones need terminating properly

 

[DIYBlues]

Thanks guys

The electic plate/outlet for the therostat is installed behind the moterised valve (WHY)!!
If I have to take the valve off to see the wiring I guess thats what I'll have to do, FYI the motorised valve is also connected to this outlet?

I don't know if its a Y-plan system

I have crimps do you mean just crimp the loose end to terminate it? (sorry)

Thanks again.

 

[Geordie Spark]

Thanks guys

The electic plate/outlet for the therostat is installed behind the moterised valve (WHY)!!
If I have to take the valve off to see the wiring I guess thats what I'll have to do, FYI the motorised valve is also connected to this outlet?

I don't know if its a Y-plan system

I have crimps do you mean just crimp the loose end to terminate it? (sorry)

Thanks again.

Y-Plan explained here: Honeywell Y-Plan Explanation

 

[Edd]

Y-Plan explained here: Honeywell Y-Plan Explanation

I like that.. will have to show my plumber friends that, may save me time talking them through it on the phone

 

[robsparky1975]

How many motorised valves are there?if only 1 this could be a 3 port(when i say port i mean how many pipes go into it,if its 3 then you most likely have a y plan,in which case the old 4 core wire would of had a common,HW ON,HW OFF,which all can become live dependant on if the cylinder has reached temperature,so when its hot, hw off is at 230v,if you are not sure a call to a local electrician would be a good option and not expensive.