Honeywell thermostat keeps tripping my power

[Ritchard]

I have bought a new Honeywell dt90e room thermostat because it looked like it would be compatible with the wiring I had for my old thermostat. I have a live, neutral and earth.
When I connect the thermostat everything is fine until it tries to start my heating and then the system trips out. I have no idea what I'm doing wrong or how to fix it.

 

[buck51]

What makes you think, you have live negative and earth, in a thermostatic switch.
I think its time to phone a friend, or someone who understands electrics.

Sorry but if you don't know what your doing you are putting yourself and others in danger.

 

[Ritchard]

I have a blue, brown and green/yellow set of wires. That's why I thought I had live, neutral and earth.

 

[buck51]

That might be the fact if it was a 3 pin plug, but its not!
And I rest my case, you do not understand electrics and should not be touching them.

 

[jackthom]

That just means someone used 3-core mains flex to wire up the old one.

What type is the old thermostat and did you make a note of how it was connected ?

 

[Ritchard]

It was a really old honeywell one. I originally tried fitting a drayton rts8 combi stat but it didn't do anything so I thought it was my three position port unit. I replaced that but nothing changed. I've narrowed down my problems to the thermostat but now don't have the old one to put back on.

 

[Galoka]

Don't ever assume anything...... Sooner or later you assume the wrong thing for example, old mechanical have a little resistor in that applies a little heat to the mechanism - this requires a neutral, live and the switched return. Maye someone used the earth core for one of these? what are they connected to at the other end. Do you have a record of it's connections? photo?

what was the old stat? why did you replace it ? a problem or just to update?

It does have the symptoms of a wiring fault (earth fault causing the RCD to trip is my first thought), but it may be a coincidental fault with something else, or a faulty new stat

When you say it trips out, what is tripping? MCB for the circuit, an RCD?

I would double check the wiring - at the stat and in the wiring centre, or where ever the stat cable terminates. What did you do with the earth cable at the stat?

If that all checks out I would start by removing the stat faceplate connect the live and neutral together with a jumper (turn off first of course) and see if the system works ok

 

[twgas]

I would agree with buck, you need help from a pro!

 

[buck51]

Galoka, He does not have a live & negative, he has a red and a blue and a green /yellow wire,and he does not know whats what he is just guessing.

A LITTLE KNOWLEDGE IS A DANGEROUS THING

 

[Ritchard]

Thanks guys, was afraid of that.

Appreciate the help, time and effort.

 

[Galoka]

Galoka, He does not have a live & negative, he has a red and a blue and a green /yellow wire,and he does not know whats what he is just guessing.

Sorry, yes, slack writing on my part, I was really meaning the terminals on the stat backplate After he had identified what each of the wires is and and that they are connected correctly

Though I wouldn't necessarily agree that this isn't something that the OP can't sort out, if they take the time to understand the wiring that they have.