Wirng troubles!!

[fishnchips]

Just seeing if anyone can shead any light on a problem I encountered today whilst fitting a pump.

The system has an old Honeywell 2 channel programmer (the one where you slide for heating, hot water and to select day/time)
With the heating and hot water selector both off, the boiler still continues to fire (old Ideal Concord CX)

With the clock removed leaving just the terminal strip fixed to wall it still fires
I've gone through the wiring and the only way i can get the boiler to not fire is to disconnect the grey wire from 2 port valve
I disconnected the frost stat to eliminate that. There is no roomstat. I think the 2 port opens and closes via the heating demand from the clock.

So before I tell them they need a new clock, 2 port valve, room stat etc can anyone make any sense of what is going on?

Cheers folks!!

 

[Whn1]

Micro switch on two port could be stuck. Turn all controls so there's no demand and chek the orange on the two port, should be dead.

 

[mfgs]

Agreed, most likely cause will be the zone valve.

 

[fishnchips]

Nice one, I'll check on monday, will let you know how i get on, thanks

 

[DustyM]

It'll be the zone valve micro switch (aux); I've had a few of these over the last few weeks - although it was getting me suspicious that I kept coming across failed ones. Usually the pump is running all the time which gives the game away.

 

[SafeGasInstall]

that is a Fish & chips voucher for Whn1 on the post on monday I take it

 

[SafeGasInstall]

op and book your self on honeywell training

 

[cr0ft]

+1 for the zone valve. Can't see what else it could be in that scenario to be honest.