hi pam i'm no plumber or heating engineer but my vokera 28 did the same. i had a burst pipe in my central heating which lost all the pressure and eventual cut out. At 1st the heat exchanger was suspected. we pressurised my system then searched for leaks and found it by hearing it. You would know if it was upstairs cos you would see it by now. I would search 1st before blaming heat exchanger...then get plumber or boiler guy in. good luck...
gerry
December 2010
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