Main combi 30 he

[Hobo128]

Job tonight
Went to see said boiler that was not firing. I reset the boiler and pump runs micro switch makes but fan does not run and boiler doesn't fire. It flashes flame symbol and fan symbol. I have checked for 240 at fan which I'm not getting and 240v from pcb at fan harness but 0v . I have it down as fault on pcb. Anyone else worked on these boilers and am I on the right track.

 

[Last Plumber]

Have you checked fuses on PCB ?

 

[JAH HEATING]

Check your air pressure switch

 

[Hobo128]

Not checked fuses. I wouldn't have thought air pressure switch would need checking as the fan doesn't run. I thought air pressure comes after the fan in the sequence

 

[Billy Bob Bob]

Not checked fuses. I wouldn't have thought air pressure switch would need checking as the fan doesn't run. I thought air pressure comes after the fan in the sequence

not on this boiler ,its a 3 wire circuit try a aps,probably sort it ,had so many fail i keep 4 in he van

 

[kb76]

Without blowing down the tubes, how do you test a 3 wire APS. Would you measure the low voltage sent via the board. How exactly does it work?

 

[Last Plumber]

Check the NC Side of the switch ( closed )
Check voltage to AP switch from PCB

 

[Hobo128]

Ok to wrap this up. Been back tonight with an aps and a pcb. Checked the air pressure switch for continuity from common to nc and no. I did get continuity but if was abit scetchy. I changed thd aps but this however made no difference so I then changed the pcb which solved the problem. In other words it was the pcb after all. I wouldn't have minded putting the old aps back in to check but it was late.
Thanks everyone