No heat :( hot water is ok, programmer or zone valve fault?

[thompo]

Hi guys,

Gf's house has just lost the heating. Its rented and the plumber cant get out until monday evening.

Had a look at it myself,
Programmer is an analog Switchmaster SM850, it has options for hot water on/off/timer and heat on/off/timer.

Hot water on/timer fires the boiler and switches on the pump via the horizontal valve in the picture, pump sounds like its running.

Untitled

• thompo
• 12 Jan 2013
• 1

When heat is switched on or timer set, nothing happens. Boiler does not attempt to fire and there is no power going to the vertical valve in the picture. When i manually operate the valve, pump activates, boiler fires for a few seconds before the valve re-sets its self and the pump/boiler stops.

Both valves (Drayton) have an orange wire going to the live of the pump.
The neutral of the hotwater valve goes to a red wire disappearing down conduit (presumably prog. HW output)
like wise the Live of the heating valve goes to a Yellow wire that also disappears.

Can try and get a shot of the wiring or ill try and do a quick schematic of what i can make out its any help?

Anyone able to diagnose? Is it ok to put power to the valve in question to see if it operates and narrow it down to the controller?

Honestly dont know much about plumbing/heating is this a H/Y/C plan???

Thanks for any help

Neil

 

[ianmcd]

the system is an S plan move the manual by pass control lever on the motorised valves across and lock the levers in the manually open position and see if it runs like that

 

[thompo]

Thats great thanks,

Yep, the pump runs and boiler fires up with the valve locked open.

Reckon it's a straight forward fix?

Thanks

 

[AdrianUK]

Room thermostat?

 

[thompo]

Yep, looks like the room stat is gone.

Programmer gives out 230v to the stat when CH is switched on.

However the switch output (yellow) from the stat does not go live. Tried turning the stat still nothing. Got the heat going by keeping the valve open.

Plumber coming tomorrow so hopefully get it sorted.
Is fitting a stat a plumber or spark job?

Thanks

 

[stem]

Is the thermostat battery operated? I've seen this happen when the battery is discharged but the display is still active and the replace battery indicator hasn't come on.