Flue liner problem. What to do? Longish

[Nick]

Advice appreciated please. Last autumn we installed 25ft of 7" flue liner to our woodburner. Woodburner is built into an old fireplace and not readily accessible. Existing flue swept thoroughly (we thought) before installing liner. Removed chimney pot and inserted liner. This was a ball breaker as there are 2x bends in the flue. Also the liner meets the outlet of the woodburner at an angle of about

30deg. Don't ask why, I dont know. All made good and the woodburner, which we installed in 1984, has provided all our CH & DHW through the winter. Last Wednesday night I decided to burn a load of of old papers that I didn't want in the bin. A while later we had a chimney fire. The chimney breast upstairs was too hot to hold a hand against. Fire was out by this time as it was only a bin of papers. Called the fire brigade who turned up pdq. Good bunch of guys. They located the source of the heat in the upstairs breast and knocked a 2ft square hole in it after checking the loft space. Had to loan them by Bosch drill with chisel to do so. Sure enough, inside of the hole is old soot smouldering brightly. They said that this may have been burning for days or weeks. They dragged in a HP hose and 'gave it a drink'. A fair amount of mess ensued, much to her indoors dismay. After a while it was agreed that the fire was out. They toddled off at about 02.30 after cups of tea etc. They returned at 07.00 just to confirm that all was ok. It was. They returned again at 19.00 to give the house a once over as a home fire safety check. This was advice really and they didn't find any great problems although they did point out a couple of non-urgent matters. They also installed two smoke alarms in addition to the three existing.

Anyway. I'm now left in a situation where I don't know how best to proceed. I have a woodburner that may be unsafe to use and I want to continue to use it. The newly installed flue liner is not going to come out again without a great deal of struggle and I have a 2ft square hole in a bedroom wall. Also a rather disgruntled better half. The hole in the wall I can certainly deal with. All sensible advice would be much appreciated. Many thanks, Nick.

[harryagain]

I have had woodburners for years.

1. There is supposed to be a cleaning hole in the chimney. Tar is formed when the chimney is cold.
2. Once a week it's a good idea to have a good blaze to burn off any tar accumulation before they get too big. A pile of newspaper is good for this as you have discovered. But the accumulation of tar was too big.
3. Your wood MUST be dry. Wet wood is inefficient and cools the combustion gases so that more tar is formed.
4. 90% of any tar is formed in the top foot of the chimney (where the combustion gases meet the cold air). If it catches fire, it all tends to fall down the chimney.
5. Did you use the correct liner for wood? They are usually double skinned. Ort the annular space is filled with vermiculite.

[stuart noble]

Very important I would have thought, and might have stopped the soot getting that hot. ISTR the chimney sweep is usually called before the flue is installed

[Brian Gaff]

Obviously the soot was not removed when it was swept due to the bends in the flue. I guess it depends if there are a lot of these in hard to gett at places, but if its the only one, maybe now its burned out its safe again to plaster up the hole. Really is difficult to call. I've seen many folk around here have weird chimney fires after fitting ttrendy heating solutions, but none of the houses has burned don... yet.

Brian

[Johny B Good]

I understood from the OP that this was the case but it's easy to miss such detail when the OP appears to be just two long 'indigestible' paragraphs (or no blank line seperators are used to guarantee the paragraphs stand out as such).

Formatting the text, even for a 'mere' usenet missive, is the key to getting your story across. :-)

[Nick]

Because the woodburner exhausted to the original masonry chimney of our 1919 cottage. This chimney failed, for whatever reason, in 2013. Rather scary to see woodsmoke literally billowing from under the roof tiles of an inaccessible roof space.

I am somewhat inclined to agree with you but safety is paramount. I know that there are no timbers within the chimney. However they are fairly close. The chimney has definitely breached allowing smoke into the aforesaid totally inaccessible roof space (hence the liner).

Nothing is ever simple.

Of course. Was going to be flippant and ask why, but thought better of it. Thanks for your help, Nick.

[Nick]

Thanks Brian, you are quite right in saying that this is a difficult call. There at least three bends in the masonry chimney. I'm rapidly coming to the conclusion that the liner must be removed. Then chimney inspected and reswept. Then new liner with terminals installed. Oh, what joy! At least it's the right time of year to embark on such a venture. Nick.

[Nick]

Thanks Harry,

1. No cleaning hole. Only accessible from top & bottom (about 7m).
2. Normally do and that's what has highlighted this & prev. problems.
3. I use well seasoned hardwood logs. Never tested any for moisture content.
4. Understandable and makes sense.
5. I may be wrong but I don't know of a double skinned flexible liner. Vermiculite filling makes a lot of sense. All the best, Nick.

[Nick]

Thanks JB,

I have been chided on NG's for using too much, or too little, punctuation or correct format.

I have had the pleasure of using NG's since about 1997. I enjoy them and they are, to me, a wonderful source of information. I do not, and have never, regarded usenet as trivial in any way.

As Mr. Lincoln said "--- you can't please all of the people all of the time".

Sorry if I have miffed you,

Nick.

[Tim Lamb]

In message , Nick writes

I suppose there is no way the fire can be run with a 6" liner? Tempting to pull a new double skinned down inside the existing.

My 12kW log burner (Clearview) was specified to have a 7" flue so I expect the installers had a reason.

>

[JimK]

/I suppose there is no way the fire can be run with a 6" liner? Tempting to pull a new double skinned down inside the existing.

My 12kW log burner (Clearview) was specified to have a 7" flue so I expect the installers had a reason. >/q

Mmm... But on the bends where the soot is the two liners will be pretty much touching so what got hot last time will get hot again next time?

Jim K

[Vir Campestris]

Andy

[The Natural Philosopher]

I take it this was NOT a double insulated flue liner?

But some flexible abortion?

There is a reason why they wont allow those to be used on modern stacks.

[JimK]

q/ I take it this was NOT a double insulated flue liner?

But some flexible abortion?/q

As it was fed in from the top I would expect some difficulty navigating 2 bends with anything other than flexible?

Unless you know differently?....

Jim K