On 9 Oct 2020 at 13:48:52 BST, "Roland Perry" wrote:

In message , at 12:28:01 on Fri, 9 Oct
2020, Roger Hayter remarked:
On 9 Oct 2020 at 11:19:40 BST, "Roland Perry" wrote:

In message , at 08:39:55 on Fri, 9 Oct
2020, Roger Hayter remarked:

PS. An important point about modern room thermostats. 98% of easily
available ones have a tiny heater to reduce hysteresis and need a mains
neutral and live connection, and *must* be connected the right way round, it
matters which is the mains supply side and which is the switched side. (It
actually doesn't matter which is neutral and which live.) If you are not
sure if your controller is mains or SELV from the boiler you need to find a
so-called two wire room thermostat which does not need a neutral connection
or
240v for a heater.

Thanks for that. So I've ordered a 2-wire one from Screwfix.

Sufficiently unusual that none of the local branches have it in stock;
will arrive in a couple of days.

Depending on the precise design of the thermostat, if your wiring is run on
the surface of the wall you may need a surface fitting back box to run the
wires into, especially if you have to cut both wires and need somewhere to
put
a chocblock or wago connector for one of them. 16mm will do.

The wiring in the thermostat location is through the wall, poking out at
right angles. If I need to also chisel a box into the wall, that's not a
problem.

Sounds a good idea.



--
Roger Hayter