Worcester Bosch Highflow 400 RSF - no hot water

Discussion in 'Plumbing and Central Heating' started by dgwarks, 10 Aug 2008.

  1. dgwarks

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    Hi everyone - I really hope someone will have an answer to this question as I am at my wits end!
    We have a Worcester Bosch Highflow 400 RSF boiler and last week it stopped supplying hot water. We only have the hot water on at the moment and the heating and radiators are switched to off.
    My father in law is an ex heating engineer so he stripped it down, cleaned everything including the inside of the heat exchanger and gave the boiler a service - still no luck. He then put a new fan assembly in as it seemed to be running slow but it still wouldn't supply more than a few seconds of hot water. He then replaced the safety temperature limiter, a new pressure release valve and a new auto air vent. We fired the boiler up and wunderbar - it all seemed great! We had hot water all afternoon, evening and all the next day. Then the next morning we were back to square one - a few seconds of hottish water then cold. Any ideas??? My father in law has many years of experience but even he is flumuxed. Here's hoping you have the answer...
     
  2. nickso

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    probably a dodgy diverter or sludge in the boiler, both common failings on these turds.

    if he stripped it down i would have expected him to find oodles of sludge.
     
  3. dgwarks

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    Thanks Nick. He did flush the tank at the bottom of the boiler out and used a acid type cleaner in the heat exchanger that did fetch a lot of gunge out. Forgot to say, the diverter was replaced. We have one of those magnetic canisters on the water pipe that takes out metallic gunge too - he stripped and flushed that out, so I can't see what else we can do... Why it should work perfectly for a day and a half and then go back to tripping out is beyond me. Already spent the thick end of £200 in parts already, so not sure where to go from here...
     
  4. nickso

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    did he clean out the really thin tube on the diverter assembly? common for blockages causing all sorts of mayhem.
     
  5. dgwarks

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    I'll ask him - thanks for the advice - hopefully it might be the problem.
     
  6. ollski

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    Flow switch?
     

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