hi.i have a glowworm combi boiler swiftflow 80.i was having problems with getting hot water.was told it was flowswitch problem,as central heating was working fine.boiler sometimes would not fire up when hot water turned on.i had f/switch replaced-seem to work fine for a few hours-then no hot water again.i would wait 10/15 mins and it works.keeps on doing this now and again,any ideas. thanks.mark