Rewiring a new cylinder thermostat help needed.

Hi all, first time post here, sorry in advance if I do something wrong

On Christmas day hot water started pouring out of the F&E overflow. after some investigation and calls to some friends who used to be in the plumbing trade, I guessed that the thermostat on the cylinder had gone. It semed like a fairly simple DIY task to replace so I decided to get a new one.

My problem now is wiring. The old switchmaster thermostat (model unknown) has a earth connected to the case, then from top to bottom a red wire (2) a blue wire (3) and a brown wire (1).

my new thermostat also has numbered terminals, but I just need to know if these numbers are common across all makes of thermostats or if they are just arbitrary.

On the new thermostat - a Sunvic 'clamp-on' type SA, 1 is call for heat, 2 is satisfied, blue is common.

on the new stat I was going to wire brown to common(3) (assuming that it is live), red to call for heat (1) and blue to satisfied (2). I will then have the earth spare so I was just going to tape it off.

I don't want to kill myself so I thought I'd find some advice from the experts before I become a statistic

I appreciate any help in advance.

boiler is baxi solo, the system looks quite old.

The only info I have is for a switchmaster SCT 1 . On this 1 is common, 2 is demand, 3 is satisfied.

Mike

Excellent Mike thanks, that helps a lot. I don't know if you know what it looks like, mine has an aluminium case with a blue dial on top. The numbers you give me seem to make sense with brown as live. Thanks.

Grant

I've only ever seen one sort of switchmaster cylinder stat and yours is one of them.

Mike

That's great, I've been trying to find this info for hours, you've helped me loads.

I'm going to wire brown to common, blue to satisfied and red to call for heat (demand), is it safe just to tape the earth off, or do I need to find a home for it?

As long as it can't touch any live terminals it's okay.

Mike

Thanks Mike, My family and I can enjoy a warm house for the new year. impossible to get a plumber at the moment so we were in a tight spot.
I appreciate your help.

Nice 1 thanks,

I have this very same existing thermostat that i'm trying to wire up to my new Vaillant VR65 Control Center. (To enable me to use the eBus system on my exisitng EcoTech plus 415 boiler) The control center only has 2 ports for the CYL thermostat control...on and off. I think I may have connected the wrong ones having looked at your colour guides...

So I'm assuming I should connect it like the following?

wire 2 - red (demand)/on?
and
wire 3 - blue (satisfied)/off?
and the wire 1 - common becomes redundant?
the thermostat states it must have an earth, so i've connected up the earth to the earth on the VR65 unit

Any assistance would be much appreciated.

Thanks
Martin