Baxi 105e main flow switch not operating

[FromMyWay]

Gurus,
Have a baxi 105e which has been switch off etc for last number of months. When started does not provide CH or DHW. Pump operates and DHW diverter M/S operates when hot tap turned on, but, main flow(ch) M/S does not operate, if I operate this manually the boiler fires up and heat hot water etc. How the diverter operate this microswitch, ie what differential pressure is caused to make the diapham plunger move. Have an internal time and external thermostat room, have not tried shorting pins 1 and 2 at this stage to illiminate. Can I do some to test the pressure movement process of valve.
Any help would be appricated.

 

[RoryD]

Blow pressure off, mains off and take side panel off for access. Remove the microswitch from the top and unscrew 4 screws. note how the innards are arranged and remove all. There's a little hole in the middle of the bottom of the housing which blocks up. Get a little electicians screw driver and 'pop' it in, it'll be sludge. Reassemble and get warm

 

[FromMyWay]

RoryD, Thank you very much for the prompt reply, could you just verify a few points in your thread. You said Blow pressure off, do you operate pressure release then turn off flow and return of CH circuit. I am not sure if the side panel of my boiler comes off but think I can get at the bits anyway. Will there not be water there? Thanks once again for your help

 

[oldplumber]

drain pressure off via a drain off cock do not use the prv in the boiler or youll need to replace that as well!

 

[RoryD]

RoryD, Thank you very much for the prompt reply, could you just verify a few points in your thread. You said Blow pressure off, do you operate pressure release then turn off flow and return of CH circuit. I am not sure if the side panel of my boiler comes off but think I can get at the bits anyway. Will there not be water there? Thanks once again for your help

Don't touch the isolation valves mate, you'll have a real bad day!!!But yup release the pressure and if poss leave it open 'on the cam', and close off the auto air vent cap...it helps. Hoping you're gas safe m8,the screws are up the LH side and when the inner cover removed they are set at the back down the side. When undone you have to hit the bottom of panel as it slides upwards...you'll see. Isolate the cold mains to the house (just in case!!). Bowl underneath as there will be some water but don't panic it will stop (remember that!!).

 

[Billy Bob Bob]

Don't touch the isolation valves mate, you'll have a real bad day!!!But yup release the pressure and if poss leave it open 'on the cam', and close off the auto air vent cap...it helps. Hoping you're gas safe m8,the screws are up the LH side and when the inner cover removed they are set at the back down the side. When undone you have to hit the bottom of panel as it slides upwards...you'll see. Isolate the cold mains to the house (just in case!!). Bowl underneath as there will be some water but don't panic it will stop (remember that!!).

and dont let it run into the pcb

 

[RoryD]

not just me...U've done it as well?? lol!

 

[Billy Bob Bob]

yes and the ridge on a baxi makes a ideal gutter to collect in front of the pcb when the doors down thank god for hair dryers LOL

 

[FromMyWay]

Gurus,
Thank you all very much for your help, I removed the diaphragm at sure it was all gunked up. Cleaned all items with clean water etc. replaced and boiler worked perfectly. Once again thanks very much for all your help it was most appreciated.