Swap two wire thermostat for two wire programable version

[levelhead]

Hi, I have a new thermostat, the old one is a Honeywell t4360b, looking for some advice please.

I have posted some pics of my old stat, i guess I'm asking does the live on the old (red wire ) honeywell go into 'com' on the new stat and the (black) wire into n/c ? pic still shows honeywell in situ. The new stat with wiring layout and manual are enclosed.

Thank you, any help greatly appreciated.

 

[EFLImpudence]

The red wire to Com and
Black wire to N/O - Normally Open which for some reason they have also called ON.

 

[levelhead]

Hi EFLImpudence

Wow, thank you for such a speedy reply. yep the last part 'on' was confusing me hence i thought i would ask before wiring.
Have a great day and best wishes.

 

[EFLImpudence]

On the instructions they have also drawn the terminal block the wrong way round.

Go by the diagram on the cover.

 

[levelhead]

Thank you, will do

 

[levelhead]

Well I have wired up the stat today but it won't fire up the boiler? I have wired the red to 'com' and the black wire to 'n/o' checked the boiler has correct psi and it does, both wires have power to them.
The stat has a click you can hear when it reaches temp so i believe that it's working. The old honeywell only had two wires so bit of a loss really. Made sure all power disconnected between checking for proper connection at the stat. Any thoughts?

Thanks

 

[ban-all-sheds]

N/C and N/O can each be regarded as either OFF or ON, depending on the application....

 

[EFLImpudence]

It is ambiguous, but would still work at some point on the dial.

 

[EFLImpudence]

....

 

[EFLImpudence]

Is programmer calling for heat?

 

[levelhead]

Hi, yes, it comes up with the symbol for heat as per manual as well as an audible click from unit.

 

[EFLImpudence]

You could try both wires in same terminal just to see if it works

but even if it is wired wrongly it should work in the opposite direction, i.e. when you turn the thermostat down.

 

[levelhead]

I may have to just test both wires together to make sure it fires boiler. Will try this tomorrow, at least that will eliminate a prob at boiler side of things. I agree if black wire was reversed it should call for heat when boiler should be off etc. I did try the N/C terminal with black wire but still nothing. Had to wrap up for tonight.
Thank you again for taking time out to respond.

 

[EFLImpudence]

Many an hour wasted over a faulty NEW product.

 

[levelhead]

Hi, started over again today took out stat and put a link in to check wiring. Turns out there was a small break at the 'live' end of the cable, was just allowing enough juice to light up the electrical screwdriver but not enough to link up boiler. Stripped back and rewired and now stat working as expected. Thank you for all your time to help solve this.
All the best.