Switchmaster Mid Position Valve Manual
Switchmaster Mid Position Valve Manual
This could be an electrician question, but as its central heating hear goes I Have a switchmaster 400 to replace with a horstmann c21,the system is fully pumped with mid pos valve.The switchmaster 400 uses term 1 ch on, term 3 hw on, and term 4 ch off.Without tracing the wireing as its been wired using unmarked all the same coluor wires.I would expect hw off to be used but there is not one on the 400.Has anyone seen this configuration used before?Has term 4 just been used to park an unused wire? Or where would it go?The boiler has pump over run wired.Any help appreciated. Yes it definately is a mid pos valve with tank stat and room stat.There is no HW off contact only CH off,CH on and HW on. I agree the contact to use should be HW off if full controll required.I have not come across this set up and think that someone has just used the CH off to terminate an unused wire.To find out the only way may be to trace all the wireing which I was trying to avoid.I thought it might be to do with boiler over run but after a think it cannot be as the programmer would be off and no live feed available for the pump.