On 26/04/2019 21:43, Tim+ wrote:
Okay, Ive got some more details about my daughters boiler. Its a WB 28i
Junior That according to WB is 15 years old.

Currently itll only make HW when the thermostat is calling for CH and
often not even then. Frequently of start-up you can hear the boiler kettle
get and the locking out (almost certainly due to over-heat). I witnessed it
do this and couldnt detect any vibration from the pump whist this was
happening so I suspect that sometimes the pump isnt starting.

Also the HW temperature is hard to control swinging between too hot and too
cold.

To me it sounds like a dodgy pump and maybe a dodgy flow switch too but I
dont really have any first hand experience of combis. Given its age, is
it worth a piece by price repair or should we cut our losses and just go
for a new boiler? (Not a Baxi).

There *does* seem to be some sort of magnetic filter in the system so
whilst slugging might be a factor, Im not sure its a major factor.

I would always repair if possible. If it is the pump then often you can
change just the pump body.

You can often get parts on eBay as so often boilers are scrapped when
fully working, or with a known fault.