Flue Seal Failure on Worcester Bosch Greenstar 18ri

FLAPJACK

I have the same boiler..same age too...so far so good for me.

Sorry about the rather dense question, but what is the indication that a flue seal has failed? Does the boiler fail to fire up?

Cheers

macman

No, water drips out out it. The boiler continues to function, but we were told not to use it until the problem was sorted.

FLAPJACK

Thanks for that..something to look out for.

Hope you get sorted soon.

macman

There's no evidence that it's a common fault on the Greenstar, and the flue assembly is presumably common to many WB boilers of that age.

Mr_Ted

I'm afraid this looks like a case of bad design and poor installation and installation requirements are very important with condensing boilers.

The theory being that any water produced within the boiler or from water vapour condensing in the flue outlet should be able to flow back into the boiler as it is acidic and be disposed of via the condense drain.
Therefore it is important that the flue is out of level with the high point being at the termination, ie run up to the outside.

It is also relevent that the flue inlet should also be water tight to for the same reasons of allowing any condensation being produced by temperature diffentials in the inlet meeting a warm outlet may cause the dew point to be reached and produce condensation, or ingress of water from the elements runnning into the boiler as it is required to be out of level, and all water running back into the boiler.

From the pictures supplied, or at least one, and i know they are not from the OP, the leaking water seems to have come from the inlet pipe.

To me this looks like poor flue connection design, but that will be hard to prove, so best to just grin and bear it but make sure maybe a lubricant is used to assemble the flue to prevent seal damage.

It is theory that the condensation running back into condensing boilers is supposed to assist in keeping the heat exchanger of the boiler clean, but I cant see that acidic condensation is going to prevent increased corrosion in some parts???

unclebulgaria

None of this sounds right to me.
The boiler flue is so designed that any water running back into the boiler, either condense or sometimes small amounts of rain water, can't leak past the seal as the inner tube is pushed past the seal by at least 10mm or more. Now, either the installer didn't cut the flue to length correctly or he damaged it being heavy handed or you're getting water ingress from the air side of the flue (the outer tube) and its running back into the boiler and flooding the combustion chamber.
This is possible when the flue is badly sited under leaking gutters or where rain water dripping off the flue tube is blown back in.

Either way its not a common fault and I've checked with the Worcester engineers I know. Poor assembly seems to be the cause here.

Johnkak

I've had massive problems with flue seals on my Greenstar 30SI with condendfit telescopic flue that i bought 5 years ago. The boiler shut down and water was dripping out the bottom after 2 years. Had a repair done by WB under repair contract, engineer told me it was a copper deficiency in pipe that spared water over the guts meaning the whole lot was replaced. 3 years since passed and the boiler started playing up. got WB out who said the same problem again a leaking flue seal, this time its uneconomical repair and walked away! i asked for the reports from the 2 visits and a flue seal wasn't issued on the original repair! I questioned WB management about this who told me flue seals arn't covered in repair contract! is this true?

Today had the boiler replaced and thought i'd dismantle the flue to check the seal and found the seal inside the bend missing! this is the internal seal that comes pre built, not the end seal or by the telescopic part.

i'm not a happy chappy!

macman

I'm awaiting the bill and will update you at that point. I did request a call from one of the managers on the final day-still waiting!

macman

Update: just received a copy of the bill as follows:
Replaced flue seals and flue: parts £59.13 +VAT= £70.96.
Labour 5 hours @ £38.50+VAT=£231.00
Total incl VAT: £301.96.

My first thought is that the parts charge is reasonable, but that 5 hours labour is not-she's been charged for the repeat visits caused by their failure to diagnose the site of the leak on the first two visits.
What would be a reasonable length of time for a flue and seal change-2 hours?
This of course assumes that it's acceptable for the seals to fail within 3 years...

PS: I've attempted to contact WB tech support several times to clarify which parts are covered under the warranty (and more importantly, which are not). They refused to tell me (how can TS not know this)?and said I'd have to speak to 'the Warranty dept'. That just puts me in a seemingly endless call centre queue for Customer Services.
Does anyone know what is covered under the standard warranty?
Edit: finally got through to WB CS today, who confirmed that none of the flue assembly is covered under the warranty at all-not even for the initial two years. So it looks like I'm back to relying on SOGA to make a claim against the installer-which in the absence of the old flue as evidence, is going to be tricky. Will probably have to agree some compromise on the charge made.

burt68

I have seen loads like this some have not been cut properly and some that have, both have seals that perish,new seals are different to old ones, now the rubber is stiffer feels more heavy duty, by the way vaillant and bosch seals are the same, both i have seen perished.I can see why flues are not covered under guaranty as there is so much potential for incorrect or bad workmanship