Worcester 24i RSF no heating

[sammathias]

Just a quick one guys. Went to a worcester 24i rsf the other day on a breakdown. Basically it has hot water but doesn't fire up on heating....
however if you run the hot tap prior to turning on heating then turn hot tap off. boiler stays fired up on heating. I gave it a good service as it hadnt been done in years. Also it seems to me the fan over run runs forever before turning off,like 2 minutes. is this normal on this boiler?
Got a feeling its the pcb but just wanted some feedback before throwing money at it. cheers

 

[ShaunCorbs]

pump run on heating or does it do anything?

 

[Last Plumber]

That boiler has a fan over run of 4 min. It also has PS proving before the pump runs.
Quite a few tests on these before you decide on a board !
Id post a link to manual but can't work out how you do it, sorry

 

[sammathias]

Pump runs on heating, case seals are all good. forgot to mention sometimes it will be a total breakdown but mainly it just doesnt work on heating until its warmed up drawing off hot water. Faulty gas valve harness spring to mind?

 

[Last Plumber]

You could test continuity through the harness, if only to rule it out.
Have you checked the heating the over heat stat hasn't tripped and check the heating sensor.
Both those will hold it off when calling for heat.

https://www.worcester-bosch.co.uk/support/document/download/release/8716145028/12831

 

[sammathias]

cheers for all the replys, harness and overheat stat all fine. ended up picking up a 2nd hand board and shes back in action! :rockon2: