Boiler stops firing up when we power cut. Have had British gas out, fault showing as F75. The last time the technician just turned it off and turned it on and it should reset! This is not doing this now. Why? No hot water

trevor, September 2008

i agree with andyo, its def switch related due to sh*te and a very popular problem with this boiler

ignore this one

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iain, September 2008

FROM TOTAL BUILD AND HEAT [1] you have .A. fault on pcb bord and you need to plug in.A. FAULT FAINDER IN TO CHACK F75 +MORE ?

andy, September 2008

f75 usually indicates you have a dirty system and the water pressure switch is dirty causing the boiler to lock out. vaillant have recently re designed this switch adding a small magnet causing any magnatite(small peices of metal in the water)to stick to the switch. you need to have your system power flushed.

andyo, September 2008

f75 is boiler not recognising pressure increase from pump starting. it has pressure sensor in bottom left of boiler (under plate exchanger)(orange if its the old problematic sensor) new ones are black,

this usually clears f75 fault

iain, September 2008