Sequence of Operation - Air pressure switch 

Thanks the best explanation of testing air pressure switches I've come across. Cheers, mate. Please keep the quality content coming 👊

Good video, common sense to simplify the problem, it amazing how many people just throw parts at a boiler until it starts to work.

Hopefully I'll fix my boiler now this man has spoken.

Keep the videos coming John.Regards,Rob,RW Gas Services

This guy is awesome keep the vids coming great content very clear

Top man, clearly explained as per usual 😁

I've seen this video over and over brilliant 👏

Great video

These guy is the best, I would love to meet him

I like this guy ... straight to the point

Excellent videos

Liking these videos.

Perfect for me being a gas plumber apprentice excellent

Thank you sir !!! Concise !!!

Excellent stuff John. I had this recently Continuity on C -NC but no power (zero) to the fan from PCB I bridged the main to feed the fan and boiler powered up.. told them needs a new PCB. Gave price they never called back so no idea if it was or not, could it have been anything else. Pump was ok and continuity on flow switch Baxi 105e combi.

Finest British education like + sub

Hi John, your explanation on Air Pressure Switch is excellent. I understand that the C (240v) will switch to NO from NC when the fan is running at correct speed (which creates a negative pressure). My question is: what will happen where there is fault and the C is connection to BOTH NC and NO? Once C-NO connection is created, the gas valve will be opened, spark fires, ...

Hi John Does the PCB of a boiler having 3 wires APS also perform the test in a sequence at APS C to N OPEN just before sending 230volts to Fan in order to prove 'no air' signal back to PCB by sending 230v? Then if open, PCB sends 230 volts to Fan which creates differential pressure which is ACTUALLY Common to NC At APS Thanks for this video.

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Controversial. But I like it. I think PCBs mostly have to be replaced due to Power Supply quality. In Ireland... disaster.

Well strange as it may seem, the Ferroli Domina F24 E pressure switch has continuity between C and NO. Thank the Lord... :)

NC no wire to it，confusing why NC designed，just for test air pressure switch？

PCB are not bullet proof. Had many boards go with different manufactures. Enjoy your videos though John

I'm no expert on this stuff (hence why I'm watching for my own information and education). I have a Potterton Suprima boiler (about 15 years old) and the number one common fault with them is the PCB failing - I believe to with poor quality dry solder joints. So I cant quite buy the 'PCBs are pretty much bullet- proof for all manufacturers' comment. Just saying.