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Baxi 105e Fan and Flue Pressure Switch

Postby thelicencee » Sat Nov 04, 2017 10:25 am

Hi All,
our daughters Baxi 105e was showing the classic flashing fan fault, I removed the main fan complete with its housing, to find that there was a small black plastic fan blade above the main 'winding' and one of the 5 blades had snapped off. I searched the web and noticed that there were a number of 'different fans' recommended as replacements, some had the same small fan blades, some had a much larger round 'impeller' type blade, but quite a lot did NOT have the small blade at all. I contacted a 'seller' that was advertising a fan without the small blade fan and he advised that this 'blade' had no real function other than to move the air above the main fan around a bit quicker but a fan without the 'blade' would do the job just as good. I also asked the same question to a seller that was selling a fan WITH the same type of blade and he said the same and that the small fan was just an 'add on' to later fans. I cleaned the fan and replaced, the fan activates and spins and will go up to full speed but the boiler still fails to light and after a short while the flashing fan fault indicator relights, however the flue pressure switch is continually 'clicking' is this supposed to happen or is this 'switch' faulty?
I have also checked that the 'flue venturi' is not blocked in any way, I assume that the + and - tubes are just straight through openings as is the main body and none of these tubes have diaphragms or filters on them. I have also connected the 'pipes' the 'other way' round, this stops the 'clicking' and the fan gets up to full speed but the boiler still wont ignite. I did 'separate' the 'tubes' but I caught the tubes while refitting the fan and they both just hung from the pressure switch, however one of the tubes had a small - line on it in blue ink so I guessed this was the tube that went to the -side of the venturi, again I then assumed that the original pipe connections were 'left pressure switch tube to the - side of the venturi and the right side tube of the pressure switch to the + side of the venturi', please advise if this is NOT correct, but the few pictures I have seen on the web seem to have the tubes connected this way round, also are the pressure switches 'adjustable' using the centre 'dial' on the switch so as to regulate the air flow to allow the switch to let the boiler ignite, OR could there be another PROBLEM/FAULT that is causing the 'flue pressure switch' to continually 'click', as some of the related answers on the 'web' also say it could be a PCB board fault, and some actually show which specific 'relay' you can change to hopefully 'rectify the issue'.
Hopefully there will be someone who reads this request that is able to HELP as our daughter is slightly disabled and suffers from the cold so relies on the central heating and obviously the hot water to be able to take a bath.
If possible would any of the kind members that reply please try and keep any instructions as simple as possible so I can understand and implement them. Many many thanks in advance for any and all replies, help and advice. Paul
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