Worcester 28 CDi pressure problems

[nickso]

The only fairly safe way to avoid them leaking is to take out all the pressure before you turn them....but I would never touch them, had a frigger the other month that leaked from the iso valve o ring after changing the expansion vessel.... was there 9 hours!!

forget the diverter, the vessel is the worst job on these turds. i only replace them if they are leaking, otherwise an external one gets fitted.

It was leaking but the trouble was I had the genuine part ordered...if it were me I would have cut the pipe and capped it then fitted an external!
Took 5 drain downs as it was moving parts which had never been moved before and needed another full strip and couple of new o rings every time.....never again.

thats why these turds take up so much time. only an alpha cbx would require more multiple draindowns to repair erroneous leaks after the initial repair.

 

[Phil29]

Hi guys,

It's taking a fair old while to finally get round to changing the heat exchanger & PRV over but i had some spare time tonight after work and decided to give it a go. After following all your advice, Everything went according to plan and apart from a few little fights trying to get some bits off that didn't want to move at first it was pretty straight forward! Apart from the homestretch.

Everything is fitted, system is pressurised to about 1.4 bar and nothing is leaking, however when i turned it on and tried to run the hot water the boiler started knocking after about 10 seconds and the pressure needle was jumping up and down about 0.3 bar. So turned it quickly off and tried to find what the problem was. It seems that i may have an airlock? does this sound right guys? If so, any advice on how to bleed it or will it just settle down as the water comes through?

Haven't tried the central heating yet due to this initial problem.

Any help would be appreciated guys as at the moment we now have no hot water or heating. Luckily it's not the middle of winter.

Many Thanks,

Phil.

 

[nickso]

run it without the gas to stop it overheating and that may clear the airlock.

is the auto air vent open?

 

[Phil29]

Thanks for the reply.

Yes i loosened the cap on the auto air vent as per manual instructions but no air seemed to come out of it. I'll try your method in the morning to see if it helps things, Thanks.

I've since had a go with the central heating out of a bit of frustration and it initially kicked in, Burners lit then after about 10 seconds the burners turned off but i could here what sounded like the pump spinning, so turned the boiler off, then on again and the CH light started flashing. Pressed the reset button and it kicked in again but then did the same as mentioned before.

Not a happy chappy! Especially since the job seemed to all go ok.

Thanks, Phil

 

[nickso]

try bleeding the pump if its especially noisy.

cant say ive had any major airlocks on these before.

 

[Phil29]

Do i bleed the pump from the big screw in the middle of it? Also do i bleed it with the system on or off and for how long?

Thanks again for your help.

Just hoping i haven't messed up anything else while changing parts, but i didn't really touch much else on the boiler.

Phil.

 

[nickso]

open the screw on the pump when the power is off, i doubt will get much out if anything.
then do it with the pump turning. make sure you open it just a little and have a rag to catch the water coming out, cdi's are specially designed to catch any stray water in the pcb compartment
you will probably see the water is heavily aerated when you open it. remember to keep topping up the pressure periodically.

 

[Phil29]

Thanks for your help nickso. Much appreciated

Have done as you've said and( Fingers crossed) all seems good !

Strangely though after bleeding the pump via the screw whilst the boiler was off then on, the same symptoms with the burners shutting down and the CH light flashing happened, the pump kept spinning( i could here the whirring noise), and whilst standing there scratching my head for about 3 minutes, the boiler reset itself and started up again??? I then heard the auto air vent make a noise and the boiler/pump started to quieten down a bit then everything started to work normally???

Do these boiler have some sort of self test mode built in to them?

Thanks again for the help as all seems to be running fine at the moment! Will keep checking over the next few days then let you know if it's all ok.

Many Thanks.

Phil.

 

[Veng]

Everything is fitted, system is pressurised to about 1.4 bar and nothing is leaking, however when i turned it on and tried to run the hot water the boiler started knocking after about 10 seconds and the pressure needle was jumping up and down about 0.3 bar. So turned it quickly off and tried to find what the problem was. It seems that i may have an airlock? does this sound right guys? If so, any advice on how to bleed it or will it just settle down as the water comes through?

I'm having this exact same problem and am not sure what to look for. I have bled the pump and followed other advice in this thread, but not replaced any components.

I shot a video of the issue: http://www.youtube.com/watch?v=PwkkzZ8LjOk

Am I looking at a replacement or service or parts replacement here??

Many thanks in advance!