worcester bosch 24i faulty fan or air pressure switch??

[tom10]

please help,
recently my fan popped so had a new one fitted, all good, but then when the central heating as timed off, if i come to either strart it again or run hot water nothing happens, but if i disconect the red hose from air pressure switch then pop it back on the boiler fires up, but again if i let the timer run or turn the heating off, then try relight, nothing happens, i have to again take off the hose pop it on, it fires up, now a new fan was installed and i`ve tried a new pressure switch and still the same, is there anything else before i have to break with the yorkshireman rule and get in a pro. all was fine up until geting the new fan. cheers

 

[Aquaheat]

Sounds as if the APS is sticking in the NC position.

This would prevent the boiler from re-firing after it has shut down.

When you remove the red pipe do you hear the APS click?

There could be a blockage in one of the tubes.

 

[tom10]

Yes you can definately hear a click when you remove the red pipe. Could this be that the pipe isnt long enough and it is getting jammed in something when the case is going back on. There are no blockages in either pipe and i have tested the boiler with a new APS switch as I though the old one was sticking but it does the same as the new one. The only other factor is a change of fan, operation was fine until i changed the fan

 

[tryitandsee]

Did you replace the fan or did a heating engineer, if latter, get them back.

If you, make sure that the tubes have not been kinked/bent/trapped or whatever and have been put back the right way on the right bits.

Make sure the venturi is not blocked with debris and tubes clear.

 

[clf-gas]

Swap the tubes round on the fan.

 

[tryitandsee]

........ and check your wiring again on the fan spade connectors are as they were.

 

[tom10]

Swapped tubes around, wiring on fan is definately right as it limits it to where you can connect things because of the fittings?

 

[mickyg]

........ and check your wiring again on the fan spade connectors are as they were.

because......?

 

[tom10]

the wires only fit on certain connectors, so you cant get them mixed up

 

[tryitandsee]

Are there three wires to the fan, black to terminal 1, red to terminal 3 white to terminal 4, if not, I've got the wrong wiring diagram

Red (+) and clear (-) sensing tubes.

 

[tryitandsee]

Amateur suggestions I'm giving, but when the front drop down panel is accessed the wiring connections to the PCB can be disturbed, make sure they are all pushed back into place, especially the air pressure switch ones.

 

[tom10]

Amateur suggestions I'm giving, but when the front drop down panel is accessed the wiring connections to the PCB can be disturbed, make sure they are all pushed back into place, especially the air pressure switch ones.

i think this is it, when undo the plastic casing the boiler works cock on, ive just tested it for the past hour turnin water on and off then heating, and no probs, then when i attach the housing back to the boiler unit and all the case back on, its doing the same thing,not going to touch owt else though, don`t want to bugger the boarrd up but at least i have an incling before i part with more cash, cheers all.

 

[tryitandsee]

With all the movement on the drop down panel, the multi pin connections can be a problem, in that one or other hasn't made a connection.

It would be good to hear what the end result is, let us know when eventually sussed.

 

[Aquaheat]

Just a thought but most of y'all have got bogged down with the connection issue!

The fact that the APS drops out when a pipe is removed seems to be a minor issue??!!

So why is it doing that then?

You can lead a horse to water but...

 

[Aquaheat]

i think this is it, when undo the plastic casing the boiler works cock on

If that really is the case then i would suspect a pcb fault on these.

Just out of interest does it start if you give the "plastic panel" a couple of taps??