help required on wiring thermostat

lapat

hi all

i have a problem with regarding a honeywell dt200 digital room thermostat

the problem being is that i want to change to this model from the old existing honeywell spin dial type of thermostat.when i have opened the old one up there is three wires red/blue/yellow the new dt200 digital thermostat only supports 2 x wires as it is battery powered rather than the old style mains wired.now im usually quite good with things like this as i come from an engineering background but i cannot make head nor tail of the wiring diagram and honeywell hung up when i said i wasnt an installer. now i dont mind payong someone to rewire this up but i dont really want to be defeated on this one......you men out there will know what i mean.
all help will be greatley appreciated as i know there is some plumbers electricians out there that may be able to help

thanks again
lapat

lapat

i know its late but someone must have an idea

YorkshireBoy

Although I'm an electrical engineer, I'm not familiar with this thermostat. However, I can explain how your 3-core cable *should* be wired...

Red - switch feed (will be live)
Yellow (with red tag) - switch wire (live only when 'stat calling for heat)
Blue - neutral (used for the 'acceleration' resistor on mechanical thermostats)

Your DT200 will *probably* have a pair of 'volt-free' contacts for the mains switching, since the controls appear to be battery operated. You should wire the red and yellow to these contacts and terminate the blue into a strip connector block as it sounds like it's not required.

Check the wiring diagram supplied to see which wire (red or yellow) goes to which terminal.

If you're still not sure, search me out an online wiring diagram for your DT200, post the link, and I'll take a look.

And before you start...SWITCH OFF AT THE MAIN SWITCH ON YOUR FUSEBOARD - DO NOT RELY ON JUST PULLING A FUSE/TRIPPING A CIRCUIT BREAKER.

YorkshireBoy

YorkshireBoy wrote:

If you're still not sure, search me out an online wiring diagram for your DT200, post the link, and I'll take a look.

If this is your wiring diagram...

http://content.honeywell.com/uk/homes/Technical/DT200/DT200Inst.pdf

...then it should be wired...

A - Red
B - Yellow
C - Not connected

Your blue wire is not used.

lapat

yes thats the one thanks for your help very much appreciated ill give it a try tommorrow and let you know if im still alive or if i have set fire to the house