Extending a boiler flue

[naffer]

Having just built a lean-to against my house side wall and thereby enclosed a flue from my Ideal Mini C28 boiler, I need to re-route its existing flue thu' 90deg and up thru' the roof of the new structure.

(Yes, it's a bit of a b*****r to have my new shed full of damp poisonous fumes :-) I plan to fix it quickly so please don't use the silly "CORGI" comment, I have University qualifications in relevant subjects and I ain't daft.)

The present flue pipework is the bog-standard 100mm flue 90deg off the boiler and straight out thru' the wall. I would like to put a 90deg bend upwards onto the existing pipe (after removing the terminal fittings) where it leaves the external wall of the house and extend up thru' the new roof with appropriate fittings.

The literature from Ideal seems to apply that vertical flues are 125mm while the horizontal flues are 100mm.

No problem, as such, but this means that I will have to replace the existing flue all the way right back to the boiler.

So: why are some flues 100mm and others 125mm on the same boiler? Logically, vertical pipes should vent more easily than horizontal ones but the diameters are the wrong way round. Is it about the physical strength of the pipework?

Any bright ideas?

naffer

[Ed Sirett]

That makes two of us :-).

1) I take it that this boiler is sufficiently young enough to obtain the correct flue parts, extensions and accessories. 2) You have the installation instructions. I have them and they are pretty clear. You'll need a vertical flue kit. It's got to be 600mm clear of the house wall.

I'd reckon that you'll need. A) Extra 90 elbow. (you should be able to reuse the one currently on the boiler.). B) 1m flue extension - this should be enough to go through the wall from elbow to elbow AND get you 600mm clear of the wall of the house. Unless you have a house that has walls over 400mm thick. C) A vertical terminal.

You wont be able to reuse the horizontal flue, which you'll probably destroy getting it out of the wall.

You might also need to support the flue from the roof of the lean-to.

[YAPH]

You mean comment that what you've done is illegal, and perhaps suggest that it might have been better if the horse had preceded the cart? ;-)

The illegality is a matter of law, not dictated by CORGI (or Gas Safe

I have University qualifications in relevant subjects ...

A University qualification in Gas Safety would seem to be the relevant subject. I got mine from Thames Valley University[1]: which University did you get yours from?

[1] Formerly Reading College, at which the Gas training is still proper Old School, although like some other post-1992 "Universities" TVU has succumbed to peddling the sort of courses where a PHD could best be described as a Patrick Holford Degree :-(

[naffer]

My I apologise; My intention was in saying " no CORGI" was to prevent unthinking responses which say "you can't do that 'cos u aint CORGI".

Because I can if I can demonstrate that I know what I'm doing then CORGI is utterly irrelevant.

Anyway, fixing the flue wasn't that hard. With the help of Ed Sirrett, Ideal's help desk & a jolly chap in Plumb Center, the job proved to be trivial. Now it's done & very safely.

********************** Mind you herewith:

Two CORGI incidents which may give you some sense of why I prefer intelligence to certificates.

1. Arriving home and hearing from my wife that the CORGI-qualified man has fixed the non-starting of the boiler. Yes he had taped down the starter button on the boiler, since it wouldn't "hold" 'cos the thermocouple was knackered and wouldn't latch on. Trivial problem to fix but given that there was a pilot light v serious.

1. CORGI-person who did boiler repair and had to be called backed since he had not screwed back the cenrifugal fan at the bottom of the boiler. Four screws, but only one done up and then only finger tight. Lots of Gas/Air leaking, badly.

"Gosh", he said when called back, "it could have blown your house up". He thought it was funny. Fortunately, I was able to call him back because his van just outside my house, since I could hear the problem, (the gas/air mixture was escaping thru' the gap he'd left and making a whistling noise), before he left. No doubt he was sitting in his van filling in lots of CORGI forms including ridiculous safety paperwork..

****************************************************** So despite these experiences: I really am not disparaging your qualifications or practical skills, indeed the fact that you look at this site and have responded so strongly shows that you take this very seriously, as I do. (I really wish you'd been the qualified person in the two events described above.)

No: of course I have no Gas qualifications but I sincerely respect those who have, BUT and it's a big BUT, the the qualifications don't make Gas persons immune to common-sense. Hence my little comment, "I ain't daft"

naffer

[YAPH]

The ideal situation is both ;-)

Without checking with my crib sheet (CORGI Gas Industry Unsafe Situations

- or words to that effect - booklet) I'd say that would be notifiable to HSE under RIDDOR (bypassing safety device).

If leaking much gas that too could be RIDDOR. In the first case I'd wonder if the person were genuinely qualified & registered.

None of us is perfect and I've had a couple of instances where I'd left a leak that was enough to register a smell of gas after a couple of hours. In both cases I raced back to the job and fixed it, but I couldn't have complained if they'd got my CORGI inspector onto me to give me a bollocking. But if I did either of the things you describe I'd seriously question my own fitness to work in this field.

[Ed Sirett]

That would so serous I'd reckon on checking whether the guy was legit or not.

This was a pre mix burner I presume, also serious. Best not to make this sort of mistake in the first place. Given that the boiler was room sealed I doubt you were in any real danger the worst that would have happened is the boiler would have run very rich, soot, CO etc.

It is sort of understandable, but not excusable, if you have a lot of interruptions.

I have CORGI inspector tomorrow (planned visit not a complaint fortunately).

[Tim S]

Ed Sirett coughed up some electrons that declared:

Good luck Ed!

Though I'm sure you don't need it :)

Cheers

Tim

[Owain]

"You're using the wrong sort of biro on your landlord's forms ... need to use CORGI approved biros, a snip at 4.99 each..."

Owain

[<me9]

A friend (a retired clergyman) said they were scolded if they used the wrong sort of pen. Their duties as registars means their records have to survive centuries, so the ink has to be the 'official' type.