Boiler Heating when Programmer Switched OFF

[richarta]

What happens now if you turn up the boiler stat?

Is the boiler stat the dial on the boiler that turns its heat up?

 

[ollski]

yes

 

[richarta]

yes

NOt sure whether it was turning that up/down (was already set to 3) or whether it was this afternoons taking of the time controller apart and cleaning all contacts in sight with meths, but the pump and boiler have now turned off when I pressed the override button to switch the boiler off.

This has happened before, though.. I think it is fixed, and a few weeks later the pump runs on forever again.

Thanks for all the help so far - very much appreciated

Tim

 

[weargas]

fast muchly,

firstly, i'm taking it from your explanation that the boiler only does ch so there's no involvement from diverter or zone valves. if this isn't the case don't take any notice of the test as it would be different if the boiler does dhw as well

there's one way you need to test the boiler and you need to do this test when the boiler is "doing the fault" so to speak.
so the boiler is firing but the timer is switched to ch off. you need to do this test with possible live electricity so caution is needed. take the front case off the boiler and locate the control box. it's the large box above the thermostat knob with 2 screws (top and bottom) in it. remove the 2 screws and remove the cover of the box. at the bottom of the box is the terminal strip. the only terminals you need to be concerned with are S/L(left) and N(3rd from left). test across these terminals when the boiler is firing but should be off. if you're getting 240v then your timer is the problem, if you aren't getting any voltage but the boiler is firing the gas valve on the boiler will be knackered. it's more likely to be the timer because if it was firing with no voltage then the chances are the pump won't be running and the boiler would boil which would make quite a racket.

 

[Fast_Muchly]

Hi
I replaced the timer which was a Siemens rwb9 with a centaurplus c27 and the fault still occurs plus there is no rattle from the boiler at all.We do have a frost thermostat to the boiler as its in the garage could this be the problem as i read in earlier post as it can overide everyting ????.

 

[Fast_Muchly]

Hi
Also as to the test the boiler does the CH and HW for the house sorry for being so long in getting back to this thread as its summer havent been using the boiler as much and been puttting up with the fault ,but need to get it fixed before winter returns .