Changing a Honeywell room thermostat

[gibbs6]

I am changing Honeywell T6360b for HOneywell DT200.
I currently have 4 wires:
white one - which wasn't being used at all
yellow & green one - earth I think
blue one
brown one

The DT200 seems to use only 2 terminals A and B as the C one is covered with a plastic tab.
I'm not sure which colours goes to A and B on the new one,

 

[sparkyspike]

The old thermostat would have had a neutral connection, which means you would have needed 2 live cables, 1 neutral, and 1 earth. The new thermostat doesn't need a neutral.

So, how did you have the old one wired up? Did you not use the neutral?

If this is the case, the brown wire goes to A and the blue wire goes to B.

 

[gibbs6]

We were using the blue neutral, the brown live and the yellow/green earth in the old one. The white one wasn't used at all and I can't seem to find out what a white one is.
The new one has a diagram which appears to use only the live and neutral on it. We have tried connecting it using the brown live in one of the terminals and the blue neutral in the other one. There doesn't appear to be anywhere to put the earth wire,
It seems to be working but I'm not sure it is right

 

[londonboy]

You need to double check what each of the cores does, the earth is probably (incorectly) a switchline or neutral. Can you remember the connections to the old thermostat? 1= Live, 2= Neutral, 3= switch line.

 

[gibbs6]

The old one had the live in 1, neutral in 3 and earth in the earth terminal(not numbered). 2 and 4 were not used.

 

[londonboy]

Yes as said above, brown to A, blue (should have brown sleeving on to indicate switchline) to B. Make the earth safe in a small connector block.

 

[gibbs6]

will do,
many thanks for the advice,

 

[Taylortwocities]

PLEASE do not assume that a conductor is a neutral because it is coloured blue. From your description your old stat probably only had a live (brown) and a switched live (blue).

Before doing anything else, you should find out where the end of that cable goes to and thier functions.

Also try Googling both Honeywell T6360b and HOneywell DT200 to see how the connections should be.