The central heating pump has now been located down to the garage but the motorised valves (whose contacts will energise the pump when required) are located indoors upstairs. The garage is on its own circuit and the upstairs obviously has its own ring (all 17th edition).

So I'm wondering...the room thermostat will control the zone valve for the central heating...powered from the upstairs ring main. But the contacts on the motorised valve will have power fed from the garage (because the pump is there).  Is this OK ?

If I do it the other way and, say, power the motorised valve and room thermostat from the garage supply then this means mains in the landing area that is not on the upstairs ring.  Catch 22 ?

Or am I worrying unnecessarily ?

You need to run the pump from the same control supply as the valves.  Where the valves are, is there no perm 230v?

Lectrician wrote on Feb 24^th, 2018, 6:55am:


Funnily enough, I'd come to the same conclusion.  Yes, one can easily put in a perm 255v supply.   Yup, 255v is my incoming voltage...provided the hob's not on.  "Long extension cable" if you recall !