Flue not sealed- Boiler closed down as Immediately Dangerous

8 Apr 2013
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United Kingdom
A gas man (who had come for another job) noticed that the flue on my Vaillant combo boiler was not sealed properly and has closed the boiler down as 'Immediately Dangerous'. He says the boiler was installed too low on the wall, which is why the flue isn't sealed properly.

The boiler was installed in 2007 - we have lived here for 14 months and there have been no problems with the boiler (except for low pressure but we think this is from the mains). The boiler was also serviced 14 months ago when we moved in and no problem was then identified with the flue.

The gas man is suggesting we need to replace the flue and lift the boiler up by about 4cm, which will be a big job coasting about 500 pounds including parts.

This seems a bit OTT to me. Can we not just cover the flue with something else (e.g.plastic pipe)?

It'd be useful to have a second opinion about whether it was really necessary to close the boiler down for this issue and also do this expensive work. I've attached some photos.

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That gas man could just have saved your and your family's lives. Appreciate £500 isn't small change, but what price on your family's safety? The boiler needs to be made safe, and to do that the boiler and flue must be lined up correctly, there is no safe alternative!
Something isnt right hear because that flue has been i the correct position at some point by the looms of it. It even looms like its been screwed with self tappers. Whats the flue like
above the boiler? More pictures if you can but yes the "gas man" did the right thing. Is it not possible to have an Rgi alter the flue system rather than lift the boiler?
Thanks for your replies. I have attached a couple more photos of the top part of the flue.

I have since sent the photos to the engineer who serviced the boiler a year ago and he says he would have noticed this because he had to put his tester in the flue. As MJGas notes, he thinks the flue was obviously in place at some point. He thinks there may have been tension and it popped out of place. He doesn't think the boiler needs to be raised and he can either push it back down and screw it, or if necessary lower the flue by drilling into the wall.

He agrees though it is dangerous and shouldn't be used.

His approach seems more reasonable than detaching the whole boiler (which would involve cutting pipes etc) and raising it by 4cm. I'm not sure why today's engineer didn't think lowering the flue was an option.
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Full marks to the guy that spotted it, my guess is whoever fitted it used the clamp to bridge the gap and it has dropped down.

Just straining it back into place is a complete no no!

Dropping the flue hole through the wall would be less work than raising the boiler I should think.
The other photos make it clearer now. Have you patched the existing hole with expanding foam? This has been known to lift flues before. I thought we were looking at a vertical flue setup at first.
Yes the boiler should be made safe as it is no longer a room sealed appliance. Air intake is obviously not intact, Flue exhaust potentially the same.

Assuming the boiler is fixed well to the wall and that the flue terminal positions allow outside, as footprints said get an RGI to reposition the flue, lot less work required.
Thanks. I have since spoken to today's engineer again and he says he advised lifting the boiler rather than lowering the flue because the latter would involve (a) drilling through the outside wall and damaging the brickwork and (b) having to remove the boiler anyway in order to do the drilling.

So, on balance, his preference is to raise the boiler, and there would not be much difference in the cost of the two jobs.
Tbh jeff Iwould get another opinion. How high is the flue outside btw?
The flue is about 2.3m up from the ground. We are on the ground floor of a maisonette and the flue is easily accessible from the outside.

The other engineer has given me a quote of 90 pounds to lower the flue if drilling is involved, so I think I'll go with this option.
I doubt drilling is an option, because the core drill will be overlapping the existing hole so no pilot hole to keep it central, good old hammer and chisel job!
I doubt drilling is an option, because the core drill will be overlapping the existing hole so no pilot hole to keep it central, good old hammer and chisel job!

Its not that hard to re drill hole with a core drill. Problem will be the size of the he afterwards unless you replace the brick it will look gash.
Thanks for the feedback. As a leaseholder I believe I need to get permission from the housing authority to drill into the external wall, but I'm sure they can provide this at short notice given the circumstances.

Two engineers have now advised I should raise the boiler by 4cm (one has only seen the photos) while another engineer thinks the cap under the flue collar can simply be pushed down and screwed on (based on the photos below). These are very different solutions to the same problem.

I have also noticed there is a gap where the flue enters the wall, which can be seen on the first photo below. Is this safe?


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