Baxi105e number of problems, bit stuck.

[dazpara]

Hi guys appreciate if anyone could help, first post here. Here goes, my mother in-laws baxi 105e DHW problem has gradually got worse. If she hasnt used the hot water for a period of time she has to run the kitchen mixer tap FULL BORE for about 3 mins to get the boiler to start its sequence and fire up, it wont fire up unless at FULL BORE, then if you use the hot water a short time later it fires up fine each time but again it has to be full bore. The flow rate is fine and ive taken the front off the boiler and on inspection i can see that when the boiler does go through its sequence on DHW the diaghram rod on the 3 port valve is making contact with the microswitch and firing up fine, but also on DHW the rod on the Heating is also making contact with its microswitch and the Heating flow is warming up.
My question here really is why is the Heating microswitch operating as well as the DHW when im only calling for DHW. Also why does the tap have to be full bore to get the boiler to go through sequence and why initially is it taking such a long time for the sequence to start when the demand has been set. Im scratching my head as ive read many posts with SIMILAR problems but not quite the same, some say diaghram problem others microswitch. Any ideas would be really appreciated, i did my Safety, boilers and analyser in june and cookers and fires today so am not hugely experienced as i do mostly installation but am keen to get as much knowledge as possible. Phewww!!!

 

[solman]

baxi diverter valves are well known to let by also dhw assembly and plate heat exchangers are also problematic a simple tip get insurance give it a month and claim as it could be a pricey fix

 

[picasso]

The dhw diaphragm is worn, the second microswitch is a pump proving switch.

 

[dazpara]

Thanks guys, have ordered the diaphragm kit and will change in the week, cheers.

 

[bellairaphon]

1 2 or 3?