Air pressure switch

[GasmanxxxR1]

Why does a boiler with a longer trap such as a wb junior combi, not need an air pressure switch?

 

[buckley plumb]

most boilers don't use aps now they use hall sensor in the fan instead - I am sure the Worcester jnrs have an aps switch though as a safety device cant remember why as the cdi does not - they did say on the course but cant remember

 

[GasmanxxxR1]

they dont have them now as they have increased the size of the trap apparently, did the course on friday, very good, best course ive been on

 

[buckley plumb]

still a nightmare of a boiler to work on