When I turn on a hot water tap the boiler does not fire up, but if I turn on the central heating the boiler fires up and I get warm radiators and hot water from the tapes?????????

Brian Dore, January 2007

When I switch the hot water on I cannot hear a click, also the micro switch is in a black plastic housing, I cannot see a cir clip and aslo there are 8 screws on the diaph houising.

The boiler is in a cupboard up against a wall, you cannot get are the back side of the valve (4 screws).

Could you advise how I would go about replacing the diaph, as this seems to be the problem with me not hearing the microswitch click, cheers.

Brian, February 2007

this boiler has a diverter vavle this vavle diaph moves a 1/8 diameter spindel at the end of the diaph housing and operates a micro switch this happens when you open the hot tap which creates a difference in pressure between the c/heating and the d/water this then starts up the hot water system, to check this you can get some one to turn on the tap and you should be able to just here the switch operate click you will need to remove the front cover first, if it does not click then the diaph will need to be replaced.this is another storey re ask the question after you have checked the diaph operation the diverter vavle is the brass vavle with a 3" dia housing with 6 screws round the end face the micro switch is in front of it in a plastic cover held in by a cir clip on the brass vavle body. keep your hands away as this is mains open contacts on the switch turn off the power and turn off the gas if you are to work on the diverter vavle a new diaph is £20 .00 a new vavle is£120 .00 bobby rob

bobby rob, January 2007