Old thermostat wiring.

[Aaron perry]

Hi. Sorry for the the noddy question but I’m hoping someone will take pity on me! I’ve recently got a combi boiler so the thermostat for my old conventional boiler is no longer needed. I wanted to take it off the wall - will the wires still be live and if they are what should I do to disconnect them? Thanks very much in advance

 

[kerching]

So, how does the boiler know to turn off when at temperature?

or has it got a wireless/hive/nest control?

depends what the pipe wrangler did with the old wiring when he fitted the boiler. The stat may  be live/might be dead, it would be prudent to treat it as live

just saying

 

[Aaron perry]

Thanks very much we have Got a wireless thermostat now, so I don’t know if the one on the wall is live or not as wanna take the box of the wall as it not on there for any purpose now but don’t know if it’s live or not as connected to the old boiler as we have got new now. 

 

[kerching]

Try checking with whoever installed it

it may not be being used BUT they may have left in in situ and just shorted the wires out behind it so it is still , in effect, in use.

get it wrong and it hurts and can kill you very quickly, and it will hurt all the time it is doing it

 

[Aaron perry]

Thanks will have to phone the bloke who done it then see what’s what with it, need to take it off the wall as putting a television in the place where it is now. 

 

[Geoff1946]

To be honest, even if a plumber told me it was dead I would short the conductors to the earth before getting hold of them.

(OK, I 'm  a suspicious old B* but I'm still alive)

 

[SPECIAL LOCATION]

Two essential rules to remember are..

1/ Electricity can kill a healthy adult in less than half a second..

2/ Assume EVERYTHING is still live unless you have proved it is dead!

A lot of "boiler installers" don't actually have much of a clue about wiring proper reliable hard-wired controls, (thermostats / timers etc..)

Which is why "wireless" is an easy option for lesser-skilled installers to fit..

and why they sometimes leave unnecessary live cables still connected! 

 

[boltonsparky]

Seeing some heating wiring delights in the past you could test it dead and then under certain conditions it could become live. The only way to ensure it is dead is finding the other end and disconnecting it. 

It's a relatively simple job but one that is worth getting someone qualified in to do. It wouldn't be the first time that someone has been told/assumed that a cable is dead and just cut off and left in the wall for the cable/wall at a later date to be found to be live. Or worst case you mount your tv on the wall clipping the cable with a screw and the bracket then becomes live.  

 

[SPECIAL LOCATION]

Boltonspark has raised a very important point to remember..

A traditional thermostat is normally supplied from a timer clock which means the thermostat wiring only becomes live when the time clock was set to turn the heating on..

So at other times of the day the wiring could appear dead as the timer is currently off!

Finding the other-end of the wiring is the only guaranteed way to conform it is no longer connected to any form of permanent or timed live supply.