Vaillant boiler safety switch pops out after about an hour?

I sorted mine by changibnf the back electronics board. it is working fine since

surj
November 2007

Hi unfortunately I do not have an answer, but I have EXACTLY the same problem., I have had at least 10 visits by an engineer who has replaced numerous parts but it still keeps happening. Sometimes it can go for a week working fine then it can pop out numerous times in 1 day.
Have you noticed a pattern with your switch popping out? Mines seems to be when the heating comes on rather than the water that may just be coincidence.
The company (who I'll not name) to which I'm paying a £17 p/month fee, are now starting to suggest that I may need a power flush because 'they have replaced most the parts' so it could be because my water in the system isn't clean?
Don't know if this is true or not but I'm reluctant to shell out a few hundred punds on a flush when I'm paying them £17 on a monthly contract which means they should be fixing any problems with my boiler. If they said it was DEFINITELY the water causing the problem then I'd do it, but I'm not convinced considering almost 10 visits later and it's still not working!

Belg
November 2007