My Ravenheat LS-100T (white star) combination boiler will not ignite to provide hot water unless the boiler is already operating the heating. There is no problem with water pressure or water supply & the summer/winter switch seems to work ok.
I have to turn the hot tap on, then turn the heating on, once ignited I can turn the heating off & the hot water will continue until I turn the tap off.

David Cullimore, May 2008

mines exactly the same hot tap only works when the heatings on not good in the middle of the summer!

jonny, June 2008