In article . com,
Daljit writes:
Hi there

My Vokera 24e Maxin combi developed this problem a couple of weeks
ago: when HW is continuously demanded, the burner switches itself on/
off, every 30 seconds or so. It means having to step in and out the
shower, waiting to catch the next stream of warm water, etc.

It's an old boiler that came with the house - we've been here 3
years. I haven't tested to see if the same problem occurs when
running the CH.

Can be caused by a furred up plate exchanger (in which case it
won't happen when running the CH). The scale in the plate exchanger
reduces the heat it can transfer to the HW, so the primary circuit
gets hotter than expected and the boiler cuts out.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]