boiler appears to be stuck on hot water even though central heating his selected and time clock and thermostate are made repair man has changed both diagphrams on diveter valve as he thought that this was the problem as soon as the top dhw micro switch is removed brieflythe boiler changes over to central heating the central heating led comes on and the boiler fires up and runs ok untill an hot water tap is turned on sometimes it changes back but most of the time it stays on hot water
their are no fault s showing on leds the plunger on the micro switch is free and not sticking the diverter valve operating head appears to work ok sometimes if you switch the main supply off and on then the system works ok for awhile again until an hot tap is turned on then the fault returns

sharon laker, May 2008

system repaired hoora ! diveter valve faulty due weak return spring, notsold as aseperate item ,engineer fitted new valve working ok now

sharon, June 2008

I would be changing the pcb at this stage, sometimes they can really give you the run around like this

T, May 2008

think we need a bit more sequence of operation to try work out whats messed up.

ie dhw demand typical

open hot tap
front pin comes out makes switch (tap led on)
top pin rises makes switch proving pump is running
sequence continues through fan, aps, ignition.

hot water demand, both micro switches are made.
ch demand, only top micro switch is made

talk through sequence

iain, May 2008

are the micro switches mixed up? top microswitch is pump proven switch. the one that faces you is hot water switch. from memory wiring to water green, to pump proven red?? not 100% on colours tho

iain, May 2008