Worcester Junior 28i Won't shut down, pump runs all the time

[stewd]

Updated..Worcester Junior 28i Won't shut down, pump runs all the time

I have a Worcester Junior 28i, which has developed a problem today.
It is fitted with a mechanical timer for the heating.

The boiler continues to run all the time, even when the timer switch is set to off.
I can control the burners via the CH temperature guage on the front of the boiler, but when turned down the pump still runs.

Am I missing something really simple here ?
I have checked the Installation guide and it isn't very enlightening, it suggest to check the Control Board.

Any other suggestions out there and surely if the heating works fine apart from the timer is it not more likely to be the timer ?

 

[madmax2024]

Had a similar problem on a worster danesmore turned out to be the post purge board which lets boiler run on to clear out boiler unburned gasses from boiler combustion chamber this may or may not apply for you pump as this was the fan running but worth a look.

 

[stewd]

A slight correction to the first post......sorry......the pump doesn't continue to run and run, if the CH temp is turned down the pump does stop after a while...and starts up again when the CH temp dial is turned back up. The timer just has no effect on proceedings.??

 

[stewd]

If I totally remove the timer unit from the control board, the CH runs on the Temp dial ?
Is it possible that then timer unit is U/S ? is there a simple check I have carried out a continuity check over the switched terminals and it appears ok when switched by dip switches/cams?

 

[gasmarc]

the timer is stuffed if it is not coming on at a set time and the boiler sounds like it is doing its thing ok

 

[CMairiD]

If it's the Worcester Bosch MT10 mechanical clock, then we have about six failures over the last couple of months.

 

[stewd]

The timer appears to be unnamed to my untrained eye, it isn't an MT10 from what I've seen...?

 

[Billy Bob Bob]

The timer appears to be unnamed to my untrained eye, it isn't an MT10 from what I've seen...?
View attachment 1351

thats a grasslin clock baxi use the same one

 

[stewd]

thats a grasslin clock baxi use the same one

is there a suitable digital replacement available ??

 

[Billy Bob Bob]

there is but its dear,unreliable and complex dont know if they do one worth a shot
[DLMURL="http://www.abcotuk.co.uk/Subcategory.aspx?catid=C2-3"]Printed Circuit Board | Circulating Pumps | Diaphragms | Thermostats | Fuses[/DLMURL]

 

[stewd]

Well...the saga continues..
I replaced the timer switch with the Worcester Bosch supplied digital timer, symptoms remain the same.
I have had a further train of thought after consulting the installation manual, the boiler was resited during the summer months into my garage. The boiler has a Froststat mode that it falls into if the temperature is low, I have spoke to the Worcester Bosch help line team and they agree that it is probably running in this mode.

How do I stop it ?
Do I need to warm the boiler up (which sounds a bit strange to me ?)
Is there an adjustment somewhere?
The sensor for the Central Heating is a small temp sensor fitted to the return CH pipe.

Any more suggestions.

 

[stewd]

Bumped....