OK, This is a new boiler and the electrician has gone missing so I have to sort the job out.
The set up consists of a boiler in the kitchen with the programmer, pump and wiring junction box in the airing cupboard some distance away. The boiler should power the pump and allow pump overrun. However, that cable is missing and the boiler and the pump come on together as they are connected in the wiring centre. This is causing the boiler to banging when it turns off.
This is not a new electrical installation. The electrician has used the existing cables from the old system when the boiler was changed to try to make the system work. Adding a new cable would mean ripping up the bathroom floor tiles that are on top of chipboard flooring, ripping up chipboard flooring or taking ceilings down.
I think I have a solution that will save this damage. All I need is a pipe stat and a 230V relay (hopefully).
My solution is to split the boiler call and pump connections in the wiring centre so that the boiler is still called for by the programmer/room stat and cylinder stat and then use a SPDT 230V relay that is activated by the boiler call wire and connect the NO terminal to boiler call wire, the NC terminal to a pipe stat (fed from a permanent live in the wiring centre and mounted to the pipework just below the mid position valve) and then connect the common terminal of the relay to the pump.
Does anyone know if it will work?
Any 230V SPDT relay recommendations are welcome.
Thanks
Adam