I have checked back through previous forums but not found the answer I'm looking for......or don't understand the answers so please bare with me:)

I want to replace my old switchmaster thermostat and beyond replacing ceiling pendants and light switches I am a complete novice. The thermostat works but is very old and discoloured and I've just had walls re-plastered and painted so want to replace it.

The existing wire colours are confusing as there is a yellow, blue and red and a green/yellow. I know the green/yellow is earth and think the red is live but the blue and yellow are confusing me!

Also I've purchased the drayton RTS2 is this one ok as I can't find a like for like switchmaster?

Your patience and understanding and advice would be very welcome

A picture showing where the wires are would be really useful. Don't forget there's 240V under that there cover

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Red to l, blue to n yellow to 3 is the most likely solution, the earth terminal should be marked as such unless unt is double insulated then it won't need an earth. Has this stat got a red indicator on it, if so it definitely needs the neutral (probably blue) can't you look at the original stat and see what the blue is connected to (there is usually a little wiring diagram in the lid or somewhere on stat).

thanks. No unfortunately there is no diagram on lid and no instructions as it's been in place well over 20years before I moved in. After reading loads of hints I was sure that blue went to N and red to live but as nowhere seemed to say about yellow...mentioned white but not yellow I wasn't sure.

RTS2 is double insulated, so no earth required. Just make the earth wire safe.

Thanks. What is best way to make earth safe? I saw on instructions it doesn't need earth, can I just cut wire back so no wire exposed and tuck out of way?

unfortunately I can't upload a photo and haven't worked out how to copy a url of pic in yet. Think I've got the answer now though so will have a go!

Well after much reading and asking questions on here I today had a go at replacing the room thermostat to a Drayton RTS2..... Red to live, blue to neutral and yellow to switch and isolating the earth on turning it back on I had the red indicator light working I turned the dial and heard the click and got all excited.....however the heating has not kicked in:( Any suggestions folks please????

Did you connect yellow to terminal 3?.

Yeahhhhh!!!!! all sorted....silly me forgot to relight the boiler pilot after I turned electricity back on! Thanks so much for all the advice and don't worry I'm not going to start rewiring my house just yet

Great news!
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Occam's Razor
" The simplest explanation is usually the correct one."

Grrrrr! I spoke too soon. I went out and came back home to find heating not on. Light is on the stat and it clicks as though it's calling for heat but the boiler now shows an error message stating "error calling for heat from external source"!

I really don't want to give up and have to pay through the nose for someone to come out so as temporary fix I may need to put old one back.

Any suggestions gratefully received.

Here is a link to the manual, http://www.draytoncontrols.co.uk/sites/ ... I.%20Guide).pdf

Thanks Trickydickie I have the manual for the RTS2 the problem is with the old colour wiring. I wish I could upload a picture but it won't let me! The old stat had 4 wires, the earth is redundant and was easy to recognise by the earth sign on the old stat (it was also green/yellow). The 3 remaining wires were 1 = command (red) 2 = satisfied (yellow) and 3 = demand (blue). The trouble I was having was I assumed that blue was neutral, red was live (which it must be as light illuminated) and yellow is the call fro heat. Now i'm not sure if I've mixed up the yellow and the blue? If I swap them over and try it what will be the worst that can happen?

Also the rts2 says it needs 3amp where will fuse be located?

Why don't you have a look at the other end of the cable and see what is connected to what?

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