Boiler flue failure

[Twanky]

Hello All,

I had a Potterton ProMax 24HE combi boiler installed about 6 years ago which recently developed a fault. An engineer visited and diagnosed that, among other things, the flue had failed - he thought probably the seals between the different sections of the concentric flue had failed.

When the engineer dismantled the flue he found that the inner tube of the concentric flue had split (please see photos) - which meant that combustion gasses were mixing with the intake air causing incomplete (and unsafe) combustion. The engineer said he had not seen anything like it before.
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Inner tube of concentric flue 1

• Twanky
• 7 Mar 2014
• 1

Inner tube of concentric flue 1

Inner tube of concentric flue 2

• Twanky
• 7 Mar 2014
• 1

Inner tube of concentric flue 2

I was surprised that the flue material was plastic but further reading has shown that this is quite normal. The flue has now been repaired but does anyone have any idea what could have caused this damage?

I'm not expecting to gather information which will enable me to raise a claim on the original installers. This is more curiosity and, I guess, something of an alert for others.

TIA
Mike Twanky

 

[ScottishGasMan]

Cant help you much, but I used to work on Promax combis all the time at the gas board and never seen that either (Im talking from hundreds ive serviced/repaired)

If i were you Id be inclined to send those photos to potterton and ask them, of course its well out of warranty, but chances are its the same flues the still use now on most their boilers so they may be interested, as I can olny assume that its a defect thats been in the flue, These boilers if i remember have a saftey limiter sensor in the heat exchanger, so if a boiler fault had caused excessive temperature to be ducted through the flue the boielr would have shut off completley to avoid damage.

and yes plastic is correct, metal would rot away in no time with the condensation that is produced.

 

[gigz]

+1. Never seen this before and worked with hundreds of them (and baxi, multifit etc) Its deffo worth letting them know as it could turn into a problem for them (and they might give you a refund )

 

[Gasescape]

One of my neebs had the exact same with a promax the other week ( vertical flue )
Previous guy had replaced gas valve etc....stripped the flue & found a large split in the inner flue ..

 

[hedsa]

Had the same on a 7 year old baxi 105 he last week . 3 sections of the vertical flue all split .

 

[Twanky]

Thanks everyone for the replies.

Gasescape, what was the approximate age of the installation you saw this on? I wonder if there's been a bad batch of flue tubing from somewhere a few years back? I'd bet that Potterton and others source from the same manufacturers.

Quick update:

My installation has a mostly vertical flue with a (near) right angle dog-leg after the first section above the boiler. Boiler in airing cupboard and flue runs through loft space and through roof. Total length about 3m.

I've written to Potterton and referred to this thread and will update this thread with a synopsis of their reply.

 

[Twanky]

Hello all,

I received a very courteous reply from Heateam's Customer Relations (no need to give the person's name).

The reply had three main points, I believe:
1) They are aware of 'a very small number of similar failures of this component'.
2) They were willing to provide a replacement component FoC if it had not already been replaced.
3) They suggest that 'there is no indication that there is a safety issue'.

I have replied thanking them and taking issue with the third point - given that their engineer described the system as 'Immediately Dangerous' and disconnected the gas supply.

I guess this may be useful if other engineers are aware that such flue tube failure can and do occur and that at least one supplier is aware and may be willing to provide the replacement part.

If I get any further info I'll add an update.

Again, many thanks to everyone for the replies and advice.
Mike (Twanky)

 

[ianmcd]

3) They suggest that 'there is no indication that there is a safety issue'.

Read more: //www.diynot.com/forums/plumbing/boiler-flue-failure.395858/#ixzz2vsMF1Il

Thanks for keeping us updated on this, well if it is not a safety issue I would like to know what they DO think it is.

 

[Paul Barker]

I'm not expecting to gather information which will enable me to raise a claim on the original installers. This is more curiosity and, I guess, something of an alert for others.

TIA
Mike Twanky

Why would you waste your money pointlessly doing that? The fault is in the components. The installer used manufacturers parts. the fault lies fair and square with the manufacturer.

The idea you even consider the installer at fault really bothers me. How can you sleep at night?

 

[FiremanT]

[/quote]

I'm not expecting to gather information which will enable me to raise a claim on the original installers. This is more curiosity and, I guess, something of an alert for others.

TIA
Mike Twanky

Why would you waste your money pointlessly doing that? The fault is in the components. The installer used manufacturers parts. the fault lies fair and square with the manufacturer.
The idea you even consider the installer at fault really bothers me. How can you sleep at night?

Paul, I had the same thought, but read again!! He says he is NOT ........ etc.

One thing though, Twanky, you refer to the ID as being instigated by the Baxi engineer, but your OP does not seem to indicate it was Baxi that spotted it?

 

[Twanky]

Thanks Paul Barker and FiremanT for your comments.

I guess that my OP could use a little additional explanation; I was just trying to keep it brief and to the point...

The fault that I called Heateam ('The Service Division of Baxi Group') for was a problem with the hot water heat exchanger. While on site the Heateam engineer tested the flue gasses (I'm not sure if he would do that as a matter of course or if he just didn't like the sound of it). He then told me that it was immediately dangerous and that my contract with Heateam did not cover it and that he could not touch it. I'm not sure if that was because he was not qualified for such work or just because of the constraints of the contract. Suffice to say HE thought it was ID and disconnected the gas - and I'm not going to quibble when someone is trying to save my life. He gave me the names of a couple of companies to try to get it fixed. He expressed a thought that the flue had originally been fitted with inadequate clamps and had possibly shifted in recent high winds thus dislodging the seals between the inner and outer flue. As a separate, much lower priority issue, he also suggested that I should have the system power-flushed.

When the repair engineer then arrived and dismantled the flue he found the split tube and passed the comment that 'he had never seen anything like it'. If he had not seen something like this before then just how rare is this? He also completed the power-flush and fitted additional clamps while he worked on the flue. I think the majority of the costs I incurred were for him attending site and doing the power-flush - so I'm not trying to pursue anyone for any compensation. I think I got value for money from that visit.

As I indicated in my OP and follow-up, I'm not trying to build a case against anyone. I'm trying to share information about a (so I believe) dangerous situation.

So the summary so far is that:
1) Some engineers have seen this sort of failure before and that it's rare.
2) Several engineers think such a failure is dangerous.
3) Baxi are aware of a few such failures.
4) Baxi may be willing to replace the component FoC under some circumstances (might be useful info for the next guy).
5) Baxi Customer Relations say that it's not a safety issue - personally I prefer to believe a Gas Safe engineer...
6) I sleep fine at night, thanks


Best regards,
Mike (Twanky).

 

[gas112]

i would say if baxi are prepared to supply the faulty part it could well be worth asking them if they would pay for the labour aspect also of this

 

[FiremanT]

i would say if baxi are prepared to supply the faulty part it could well be worth asking them if they would pay for the labour aspect also of this

Particularly as they had already had one of their engineers on site. He presumably was not aware that Baxi was aware of an issue?

 

[ianmcd]

Twanky you certainly are more reasonable than most, I would be sticking this to Baxi big time, their own employee failed to diagnose a known manufacturing fault and told you seek help elsewhere, when he should have replaced the faulty flue FOC, I would ask the company that carried out the remedial works to split their invoice and demand that Baxi pay for the flue repair

 

[Livesgas]

Ive noticed that the inner Baxi group flues have been changed to a white plastic recently? Even the flue elbows. Maybe they no something?