I've got a similar problem with my Baxi 105e. I've had several plumbers look at it and I'll describe what they've done (to no good effect). The fault is that once the preheated water is gone, the hot water tap runs cold. If you turn the boiler off, then hold the reset nob for a few seconds, the boiler will then function correctly, to fill a bath for instance. Once the bath is full and the hot tap is turned off, further attempts to get hot water will fail until the boiler is again reset. Confronted with these symptoms, the first plumber noted that pressure was a little low and replaced the pressure relief valve. Not suprisingly this made no difference at all. The second plumber replaced "the sensors". He also pumped some air in via a valve at the back of the boiler to check that something else was working OK, and he said it was. He said if this did not cure the problem, then it would probably be the heat exchanger, which could be clogged up. He explained that an old heat exchanger could be cleaned out by a professional company, and reused once it was cleaned. He suggested that changing the heat exchanger was a big job and hinted that it probably wouldn't be covered by my boiler cover with Southern Electric. Hope this info helps rule out a few red herrings. I'm still deciding what my next move should be. Good luck
Paul, March 2008
