Ok - thanks all - kudos points to Nickso for accuracy and instructions, followed closely by gas4you.
Spent half today trying to get mixer valve off (13 years old - well seized), to have internal plastic bits shed all over floor....
Finally got through to Gledhill sales after 4pm, to get part...
Hi - Yes the pump is runnng at it's highest speed.
Which sensors? Boiler or Boilermate? I think the boiler overheat sensor is probably working as it should be - but am open to suggestions. The boiler runs for quite a while then shuts down even though the Boilermate demand neon is still on...
I have a Boilermate II, fed by Myson 80SI, which are both now 13 years old.
Replaced boiler-pump* (on Boilermate) approx 2 months ago after it became noisy following a drain-down & refill. Also added Fernox MB1 inhibitor.
Everything appeared ok for past 2 months, but 2 days ago hot water...