New room thermostat wiring problem

[akaydnc]

Everything working well until I removed existing Honeywell rotary room thermostat and Installed digital Heatmiser programmable room thermostat.

Existing wiring is 3-core mains supply to manual rotary timer. From rotary timer there is 5 core wiring leading to Boiler. And from rotary timer, there is 3-core cable to room thermostat. (I would assume that 3-core to room thermo is live, neutral and switched live.)

Upon completion there is no power at new programmable thermostat.
I have tried combination of different wiring at room thermo but nothing. Any help would be greatly appreciated.

 

[martinxxxxxx]

When you brought this did you look at the specifications and have you taken a look at the instructions at all. If it is the model I have just googled then it is a TBase10 connection that you need,.

Martin

 

[akaydnc]

I had checked with the manufacturers, before purchase and they said I would need Live , Neutral and switched live.
There are 3 wires at the thermostat, however I will have to confirm whether they are L, N and SL.

Also presumably the existing rotary dial thermostat must have worked with similar wiring L,N and SL. I will have to check the Honeywell wiring.

 

[AndyPRK]

did you take any pics of the old stat and the wiring ?

 

[matt1e]

did you take any pics of the old stat and the wiring ?

would be a good start

(I would assume that 3-core to room thermo is live, neutral and switched live.)

never assume anything mate especially with heating controls, did you measure the voltage on the origonal stat?
it may be that the boiler is using "volt free" conections for external controls

as well as pics as stated above, make, model or even better GC number of boiler would also help

 

[ccam108]

When you say "3-core" do you mean brown, blue and green/yellow, or brown, grey, black and earth? If the former, you need a thermostat that doesn't need a neutral, as the three cores are live, switched live and earth. DO NOT try wiring your new thermostat up if this is the case, as you could give someone a nasty shock!

Colin C

 

[akaydnc]

New Heatmiser thermostat has four terminals, and according to their helpdesk, wiring as follows. Existing is 3-core(brown, blue and green/yellow)

L = Brown
N = Blue
A1 = connect a small piece brown wire between L and A1 to form a bridge
A2 = green/yellow (switched live)

Didnt work for me, however is this bridging common in electrical circuits.

 

[mfarrow]

It sounds like you have a volt-free thermostat connection. What's the model of the timer?

Green/yellow is *never* switched live, always earth, unless someone's been naughty with the wiring.

How do you know that the g/y is a switched live in this case? The helpdesk certainly didn't tell you that, did they?

 

[ban-all-sheds]

A2 = green/yellow (switched live).

 

[akaydnc]

Had removed the offending thermostat on Wednesday and fitted back rotary Honeywell thermostat. My OH is happy with heating back on.
But on a serious note, I will have to check the existing wiring L, N, E, SL etc etc. Would not be upgrading to digital until further knowledge is acquired.