how to replace water pressure switch on worcester 24i junior

[redrob7]

hi have problem with worcester 24i junior combi boiler after reading lots about problems with these boilers i'm guessing i need to replace the water pressure switch whitch i can buy but carn't find any info on where it is or how to replace it.... problem i have is red light flashing 4 x a second checked fan and air pressure switch pipes problem only happens now and again more so if i open hot tap fully if i open slowly no problem any advice welcome thanks redrob7

 

[Rob]

Just read the fault finding section and it doesn't mention the low water pressure switch.

 

[Paul Barker]

sat on top of heat exchanger right hand side front pipe.

GC no. H49-603 Manufacturers part 8-716-105-111-0

Might only need hole raking out. bridge it temporarily to prove it. OH stat is also in series with it as an interuptor need to prove that also.

If both working expect to bell out orange wires on ST16 of board, but I prefer to prove components negatively during actual working conditions by attaching clip leed across them momentarily. Beacuse it is one thing to pass a beep test from your continuity tester when at rest and something entirely different to pass the necessary current to satisfy the pcb during working conditions.

 

[redrob7]

thanks for replys guys was thinking it was water pressure switch because problem happens more often if i run taps open wide quick rather than only open taps a bit. will look again at reader info and try cleaning w p switch out will post my findings here

 

[Paul Barker]

You are barking up the wrong tree. system water pressure is totally unrelated to tap water.

You are describing an APS lockout 4 x per sec. water pressure or oh stat lockout is once per second..

just because it locked out at aps testing doesn't mean it is the aps, nor does it mean it isn't.

 

[Malauton]

Paul Barker have a reply that interested me but I dont know if he still uses the forum--

I am a retired Corgi fitter (Knees gave out) My son has a Worcester 281 and I have located the fault to no continuity across the water pressure switch

Paul indicated it can be cleaned out--anyone have any more info on that !!!

Thanks

Mal

 

[ChrisR]

more info on that

There's little so say, you poke and wiggle , avoiding the rubber membrane.

 

[Malauton]

Thanks for the reply
I cleaned the gunk out yesterday and refitted it.
With wiring disconnected
-Test for continuity acros switch terminals = OC
-start to repressurise system at 0.5 bar = switch closes
-depressurise system below 0.5 bar = switch opens = OC

reconnect wiring
system presssure = 0.2 bar
switch on
open DHW tap Boiler goes int fault--one blink/sec
reset and run heating --system runs
drive system to overheat --overheat stat operates cuts gas to burner, keeps pump and fan running

What I cant understand is how the system will fire and run with the pressure too low to operate the pressure switch? The overheat stat and pressure switch are in series if either is OC this should prevent fire up?

Rechecked the pressure switch operation (and rechecked) as above and all ok

reffitted everything , filled purged and vented stystem ang all working ok
Any Ideas