Worcester 24i Junior Problems....

[mbga9pgf]

Hi all,

after just fixing my worcester 280 which suffered an expansion vessel failure and pressure relief valve failure, I am aghast to have discovered I have similar issues with my worcester 24i LPG. this is the non greenstar variant (standard boiler, non-condensing). I will give a run down of what happened.

Firstly, someone (previous owner) had, for some reason, switched the bosch system pump onto its lowest setting. Unfortunately, this wasnt enough for the boiler CH loop. It required setting III.

The boiler lit, as normal, and as this was the first time it was lit, I kept an eye on it for a minute or two. Unfortunately, the pressure starting climbing. When it hit 3 bar, I thought, enough is enough. unfortunately, I was too late.

I heard a hissing sound, which I originally thought was steam outgassing via the PRV. unfortunately, it was the expansion chamber rubber going, and the pressure vessel pressure leaking out of the back of the pump inlet.

I had switched off the demand as soon as I realised what was happening (about 2 seconds later). The system cooled and I went to take a look. The concerning thing was this. even though the system was pressurised to 2 bar, operating the PRV knob didnt dump the pressure. Not even a little bit. Which is a bit of a worry.

Problems I now have, the pump is dripping very slightly at the inlet. I am hoping this is simply a blown O ring (is this likely, or will it be more serious?), rather than anything more serious with the pump. I know the expansion vessel is gone, so will need replacing.

As to the PRV, I am unsure as to whether the PRV is at fault or whether there is a blockage in the pipework. Until I get it off and get to test the PRV and the pipework downstream of the PRV I wont know.

Does anyone know how easy it is to get to the expansion vessel on these? at first glance, it appears to be a complete and utter ballache, hidden behind the boiler casing. Any top tips as to how to get to it? The 280 was an absolute dream to fix, obviously worcester clocked that it was too easy, when they designed the 24i .

 

[Gasguru]

At the time these boilers were launched Worcester were advising the pump could be turned down but at some stage they appeared to change that advice. The bypass was too small and system noise was often a problem with the 6m pump.

There is a major design fault on these boilers...the flexible hose leading from the pump to the PRV and vessel can become blocked. As you havce found the pressure rockets until something gives.

Get a new hose...AFAIR it comes with a new plastic manifold for the vessel/PRV connections. Re-charge the vessel..it may be fine. Change the auto air vent and prv whilst you're at it. St the cold system pressure to 1 Bar. The last time I did this the pump had to come out and it was a pig to remove the hose retaining clip....yet more design faults.

 

[nickso]

the retaining clip is hit or miss on these, some fall out, others are a cow to get out. there's enough room to do it with the pump in as long as you don't have shovels for hands. i find the best way to take out the stuck ones is to just use brute force. the worst that happens (so far) is the clip deforms and you just bend it back.

as GG says the junior is a bit of a bomb waiting to happen. if the expansion vessel is burst i would add an external one with it's own prv.

 

[mbga9pgf]

At the time these boilers were launched Worcester were advising the pump could be turned down but at some stage they appeared to change that advice. The bypass was too small and system noise was often a problem with the 6m pump.

There is a major design fault on these boilers...the flexible hose leading from the pump to the PRV and vessel can become blocked. As you havce found the pressure rockets until something gives.

Get a new hose...AFAIR it comes with a new plastic manifold for the vessel/PRV connections. Re-charge the vessel..it may be fine. Change the auto air vent and prv whilst you're at it. St the cold system pressure to 1 Bar. The last time I did this the pump had to come out and it was a pig to remove the hose retaining clip....yet more design faults.

Awesome. THank you both so much. I think I know the problem now. Although when I was trying to pressurise the Pressure vessel using a bike pump, it didnt seem to be retaining much pressure.

As long as the pump hasnt gone, hopefully it wont be too much of an embuggerance to fix. Thanks for the gen regarding the blocked pipe.

Regards.

 

[nickso]

remember to de-pressurise both sides of the hose. if it's blocked you could have 1-3bar of pressure in either side. de-pressurising the expansion vessel is a good idea too as it generally means less water escaping all over you.

also remove and check the guage tube, if the hose is blocked that won't be far behind.

 

[mbga9pgf]

remember to de-pressurise both sides of the hose. if it's blocked you could have 1-3bar of pressure in either side. de-pressurising the expansion vessel is a good idea too as it generally means less water escaping all over you.

also remove and check the guage tube, if the hose is blocked that won't be far behind.

Unfortunately, the expansion vessel has blown. I used my bike pump on it and air is getting across the barrier and into the leak.

What does the Auto Air vent do by the way? I notice this is part of the circulation pump. It looks as if an inlet or outlet is leaking on the circulation pump, will this be the AAV, o ring seal or could it be the actual pump?

Thanks in advance guys. Love the fact the more modern boilers dont have nuts and they have gone for the more user friendly quick fit style... makes things that little bit easier to fix.

Bit of a shocker on the braided hose. Did Worcester recognise this snag and did they ever do a free programme of upgrades/repairs for boilers this affected?

 

[Gasguru]

The auto air vent helps to purge air from the boiler...as it appears the hose is blocked with crud the aav will be in a poor state.

Given the vessel has gone it would appear your system could be pretty corroded. As Nickso says replace the gauge too.

Worcester have some really second rate "engineers". They try and join the plastic pump to a brass/copper part with a fibre washer and expect it to seal...it doesn't...perhaps this is their backup prv given the hose fiasco. You'll find a "rubber" top hat washer on one pump union and a fibre on the other. Suggest you replace both.

Modern boilers are carp...they use O rings and clips since they can use a de-skilled workforce and plastic parts are cheap. Clips and O rings do not make the jobs easier...just breathe on some and they leak. Long term it's all rubbish.

A manufacturer owning up to a design fault...no chance. Worcester make some of the worst boilers for maintenance but the flashy ads don't tell you that

 

[mbga9pgf]

Cheers Gasguru. Thats all top Gen. Can you buy the washers as single items or are you expected to buy an overpriced set for a single part? Goiod news then as I am expecting it to be the washer thats blown.

Having had second thoughts on the EV, it could be that the blown washer is causing air to vent from the drained system when I pump the EV up. Although I think we both know that wont be the case!

How do you rate Valent over Worcester? Or would you use another brand?

 

[nickso]

vaillant are also ****e IMO. i have no idea why some to seem to rave about them.

to be fair i don't think there is a single boiler currently available that i like, i've not seen some of the rarer fodder though.


on the expansion vessel. if you pump one bar of pressure into it with the prv clear and open and it loses it within a few days it's officially goosed.

single washers are available but the pump washers can be a bitch to fit. the top hat washer nut has to be removed from above and can be a real pig to get out.....if the boiler is old enough i have seen the old worcester classic where the threads come out with the nut. it really is the new 28 cdi.

 

[mbga9pgf]

vaillant are also s***te IMO. i have no idea why some to seem to rave about them.

to be fair i don't think there is a single boiler currently available that i like, i've not seen some of the rarer fodder though.


on the expansion vessel. if you pump one bar of pressure into it with the prv clear and open and it loses it within a few days it's officially goosed.

single washers are available but the pump washers can be a **** to fit. the top hat washer nut has to be removed from above and can be a real pig to get out.....if the boiler is old enough i have seen the old worcester classic where the threads come out with the nut. it really is the new 28 cdi.

Any top tips on removing U clips and putting joints back together? I am planning to use silicone grease on the o rings and am going to take my time... Is it about technique or pure brute force with these things?