got vaillant 828 turbo plus 3y old.hot water slow to cut in sometimes takes 20 mins sometimes 10 secs,have fitted new secondary heat exchanger and diverter valve also power flushed system and fitted a magna filter but boiler still slow to react to hot water demand.heating works fine water and gas pressures also fine if anyone has any ideas they would be most welcome

john, January 2006

ive been trying to email you all day but it wont send so well have to do this the hard way first of all to the right hand side of the boiler there is a brass fitting if you look in your manual this is the aqua sensor when you ask the boiler for hot water the green warm start light should start flashing on the front of the boiler if not on the aqua sensor there are three wires there should be 2volts dc across the red and green wires if not you need to isolate the water supply and remove the aqua sensor split the aqua sensor and clean the propellors inside reassemble turn water back on and test if the green light starts to flash now and the boiler works it is advised that you renew the whole sensor if the light still doesnt flash this is usually the circuit board at fault ( these instructions are are all guied at the fact that ther are no problems with the diverter valve so ensure the new diverter valve is installed correctly and is operating the microswitches on it ) email and let me know how you get on

mike, February 2006

hi john its mike again does the green warm start light flash on the front of your boiler when there is a hot water demand ( when the boiler is in fail ) if not you need a multi meter to test the next sequence of fault ( i think this could possibly be the aqua sensor had a very similar problem today email me at michaelhalliday4@hotmail.com with your answer

mike, February 2006