Worcester 28CDI Intermittent Air Pressure Fault

[Agile]

You can eliminate the LP water switch by bridging it out temporarily!

Later models did not fit them !!! The replacement part is now a brass plug.

It seems very rarely remembered that the LP switch gives the same indication as an APS, its not mentioned in the book and so the book readers at Worcester dont know about it! They are not boiler repair engineers!

There is more to fail with an APS than just the switch itself! I was fooled by one on an Ariston which tested OK but in use did not return reliably to the rest position.

Tony

 

[clf-gas]

The LP switch on the W/B acts in a simmular way to a HL stat.
If its blocked or sensing Low water then the boiler locks out.

Fairly sure of this Tony.

APS is the more likely cause, seen this even on my installs within months of installation.

 

[Gilly10]

Hi - thanks for the advice - Had a look round last night and found the sensing tube at the top had a hair line crack (where it had over time gone hard) I've replaced this with some generic tubing - boiler is now working fine

However;

Have spoken with Worcester and others - can't seem to get the fan that cools the motor without replacing the whole fan assembly - doesn't seem critical? Any pointers appreciated. (Plumbcentre want £98 for the part - I'd then want it fitted professionally)

 

[corgiman]

I would not worry about the cooling fan too much

 

[lee1976]

you say it only happens when you are in the shower is it a thermostatic mixer valve??????

 

[CorgiIOW]

Had a quick look at the replys, 28 CDis have duel speed fan , unlike the 24 CDis, and yes the plastic tubes perish, also because its a duel speed fan, sometimes the higher speed , does not reach momentum, hence the aps does not react ,,,, hence lock out !

If in doubt, yes change the aps, ( because its cheeper ) then look at the fan, but more importantly, the venturi , within .

Dave.

 

[Plumberfromhell]

Hi I have a Worcester 28i RSF and also when I have a shower it goes cold. I have replaced the H/W sensor but unsuccessful and when I press near the mechanical timer or pcb connection it makes a few buzzing sounds and cuts in/out.
I would just buy a new pcb but am not 100% sure it is the problem. Could the connection block be u/s and can you buy wiring kits/bits?

I am getting lots of stick from my wife so any help gratefully received.

(I have called a plumber out before but he couldn't find fault as intermittent. Not sure Worcester would be any better?)

 

[ChrisR]

Careful - showers go cold for all sorts of reasons to do with water flow - nothing to do with aps/pcb. Engineer needs to monitor temperatures, pressures etc.

 

[CorgiIOW]

Hi I have a Worcester 28i RSF and also when I have a shower it goes cold. I have replaced the H/W sensor but unsuccessful and when I press near the mechanical timer or pcb connection it makes a few buzzing sounds and cuts in/out.
I would just buy a new pcb but am not 100% sure it is the problem. Could the connection block be u/s and can you buy wiring kits/bits?

I am getting lots of stick from my wife so any help gratefully received.

(I have called a plumber out before but he couldn't find fault as intermittent. Not sure Worcester would be any better?)

Sorry for no responding to your post earlier, you may well have solved the problem by now.

As said, it may not be your boiler that is at fault, do you get intermittent hot water from all of your taps ??? Or just the shower.!!