I have a saunier duval sd 623 combi, I have no hot water or heating.
When I turn a tap on the second(main) heating flame does not kick in, so I presume the boiler is lacking some pressure change, can somebody tell me how to fix this problem?
I have read a few of the responses recently asked about these boilers, but still very confused, does anybody have a drawing diagram for one of these boilers?

Phil, March 2007

Possible vacuum switch or water pressure

alan, May 2007