Tarry liquid dripping down outside of boiler flue

Can anyone suggest possible causes of the following:

Camray 5 65/90 utility boiler (oil fired) installed March this year in a utility room which is an extension built on the end wall of my house. (Old house, built 1835). Other side of the wall is a fireplace with wood burning stove, which has flexible flue up chimney. Boiler flue rises vertically from boiler, then angles through wall and joins (presumably) flexible flue pipe also up chimney.

Thick tarry liquid was dripping from the underside of the boiler flue where it angles through the wall. I've hacked away the cement at the point it is dripping and lots has oozed out. But it's still dripping 4 hours later, although it's now much more watery. Brown, with a burnt smell.

I can't see any pipework running through the wall directly above that point (after all, it's the outside wall of the chimney), although there is pipework running through a few feet at either side, so I guess there could be a leak there.

Can't see it could be damp in the chimney (dripping for 4 or 5 hours?)

So could it be the condensation from the boiler flue? Possibly the angled flue through the wall not properly connected to the flexible flue going up the chimney? If so, sounds pretty dangerous.

Any other ideas? Hoping not to have to hack right through the wall...

Thanks

Martin

Probably not dangerous, just a pain.

Flue is almost certainly wrongly assembled, and most likely upside down. Post a photo (or two). The Camrays work almost at condensing mode, so produce a lot of condensation in the flue.

Thanks. Couple of photos at http://uk.pg.photos.yahoo.com/ph/mrh_cv/my_photos

Boiler turned off at 10.30 and now stopped dripping so sounds very likely to be condensation I guess.

Flue pipes are correct way up, but there should be an access plate on the bend so the flue can be swept.

Unless you KNOW there is a liner up the chimney, there may not be one. Did you put the boiler in, or did a firm do it? If you didn't do it, you need to get the firm back to sort it. If you did it, you will need to break the wall up round the flue and get to the end of the pipe where it goes into the flexi that should be there. You need to fix it, as the mortar in the wall is degraded by the condensate. Another photo when you've made the hole will be useful.

Was installed by a local firm. Boiler was a replacement, and connected to existing angled flue pipe. I'll get on to them this morning...I hope.
Thanks again

Decided to hack through the mortar and the problem is clear. See picture at http://photos.yahoo.com/mrh_cv
The flue from the boiler was just laid into the flexi, a piece of old cast iron pipe laid over it, and mortar slapped around it.
Can't really blame my plumbing/heating man, as we all agreed to join onto the existing flue which appeared to have worked perfectly well since 1997 when we moved here. Maybe he should have known better...
So far as I can tell, this was installed around 1970 when the previous boiler was installed.
He's coming tomorrow (Tue) and hopefully we can rig up something temporary so I can have the boiler on. (He's a sole trader so I can't expect him to walk away from another job).
What would you suggest as a temporary fix? And what sort of adapter would be needed to connect from the flue pipe from the boiler (4" dia) to the flexi liner (seems about 5.5" dia)
Thanks again
Martin

The liner looks like 6" from the photo, but I could be wrong. The right joint is a flex to vent connector, a temporary fix will have to be decided on site

Oil boiler flue liners struggle to last the life of the boiler due to the sulphur content of the burnt fuel, and some condensation.

Therefore the 1970 flue liner should have been changed when the boiler was. Your installer is a bit of a chancer, clearly he hadn't inspected it.

However, if your wooburning stove does share the same flue pipe - which would be surprising - the thick brown tarry liquid would indeed be tar-ry.

Judging by the quality of the Copex to flue joint the previous (not current) installer clearly is happy to bodge things up. A wood burning stove usually uses a much higher rated flue liner than an oil burner, because the temperatures involved can be very high.

I suggest you get a chimney sweep to investigate and clean before you cover it all up again. I wouldn't be surprised if the flue liner is in tatters.

If you do have loads of tar up there (its a wood burning by product) it could catch light and then you will have a problem.

Thanks. There is a separate flue for the woodburner, which was installed when we moved here in 1997.

Does a temporary repair have to be completely airtight to stop dangerous fumes leaking out?

We've made a temporary connection using an old Peak Freans biscuit tin (!) and packed it around with fibreglass insulation. Seems to be working OK.
Plan is to drop in a new 4" flexi liner inside the 6" liner that is there, as 4" is quite adequate.
Any problems with that?
Again, thanks for your help.

simond said:

Oil boiler flue liners struggle to last the life of the boiler due to the sulphur content of the burnt fuel, and some condensation.

Click to expand...

Do they? I've seen old liners in good condition. Why wouold that be?

Therefore the 1970 flue liner should have been changed when the boiler was. Your installer is a bit of a chancer, clearly he hadn't inspected it.

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Judging by the quality of the Copex to flue joint the previous (not current) installer clearly is happy to bodge things up.
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I suggest you get a chimney sweep to investigate and clean before you cover it all up again. I wouldn't be surprised if the flue liner is in tatters.

Click to expand...

These statements are not in the accepted style of a "professional" IMO.


A 4" down a 6" would be OK, but it might be awkward fitting it, though I would do it that way.

(Huntley & Palmers would have been a better choice )