"xena" wrote in message
...
Hi there

I would really appreciate help with this.

The thermostat for the downstairs heating in our house has never worked,
so I took a look at it today. There are 3 wires going to it:
green/yellow, blue and brown.

The thermostat is a Drayton RTS1, which has 4 terminals: Neutral, Live, 3
(Call for heat) and Earth.

Currently, the wiring goes: Brown to Live, Blue to Neutral, and
Green/Yellow to Earth.

This leaves nothing going to the 3 (Call for heat), which I guess is why
the thermostat isn't working!

I'm guessing that one of the following is the case:
1) the green/yellow wire may actually be the 3 (Call for heat)
2) the green/yellow is actually neutral, and the blue is the 3 (call for
heat)
but I need to know how to check this without fusing the system! Also this
would leave no earth - is this likely?

I've got a digi multimeter, and there's 230 Volts coming down the brown
(when checked against either the blue or the green/yellow), so that's in
right, but how do I find out how to rewire the other two?

Ok, a bit more information. I've found the cable that goes from the
thermostat downstairs to the heating system upstairs, and posted a pic he
http://www.ukosborne.co.uk/images/wiring.jpg
with the relevant bits labelled up.

Many people have said that if, as suspected, my green/yellow is not actually
an earth, then the system should be rewired. I'd rather not do that if
poss, although now I've found the cable, I wouldn't rule it out. The
spaghetti in the above pic shows what a nightmare it would be wiring it in
though. Also, personally, I'm not too concerned about the lack of earth as
the thermostat explicitly states that it is double insulated and no earth is
required.

Other suggestions are that I use a two-wire thermostat. That doesn't help
me at the moment as I don't know which wires are which!! I don't know if my
green/yellow is actually earth, or maybe a neutral in which case the
thermostat I have is fine.

What I really want to do now, is to explicitly establish what my blue and
green/yellow wires are.
Possibilities for the blue:
1) It's a neutral
2) It's a switched live (call for heat)

Possibilities for the green/yellow:
1) It's an earth
2) It's a neutral
3) It's a switched live (call for heat)

I have a multimeter if that helps?!

The fact that the heating won't come on if the thermostat faceplate isn't
attached may give a clue as to which wire is which, but I can't decipher it!

I've found a PDF of the RTS1 here with a diagram that shows that it is
normally open.
http://www.climate-eu.invensys.com/i... &CAT3=CATIT55
or
http://makeashorterlink.com/?V2D8258C9

I'm looking at the latest release on that page, 11/02. My thermostat is Fig
1, RTS1.
Just to recap, currently, my green/yellow is going to the optional earthing
point on the stat, my brown to live, my blue to neutral, and nothing to 3
(call for heat), hence why the stat doesn't work, and my heating is on all
the time!

Thanks to everyone for their continuing help, hopefully we're almost there
now.

Cheers
xena