Chimney leaks

[Khayamanzi]

OK this year I have strated getting tar deposits running down the inside of my chimney and in extremes, splattering on the top of the stove. The chimney appears to go up through a cast flange and out the roof of the boat and it is between this flange and the chimney flue that the tar drips. I have tried re-packing between the two with fire cement but the tar still seems intent on seeping down. Someone suggested trying to get a double skinned chimney but as with most things on a Liverpool boat, the chimney size is non-standard diameter and it's hard enough trying to find a replacement single skinned chimney!!

 

Any suggestions or tips from people who have had a similar problem greatly appreciated.

Edited December 12, 2004 by Khayamanzi

[Bernie]

Have you tried a chimney liner, these can usually be obtained in different sizes from most chandleries.

[John Orentas]

The only answer is a double skinned chimney, but the inner linner must fit within the flue pipe, any condensates will then find their way back into the stove.

 

There are other advantages in such a system, the linner will stay much hotter than a simple chimney so not allowing to much cooling of the flue gasses, encouraging better 'drawing' of the stove.

 

Have the linner skin made, any sheet metal worker can do it and should not charge too much. Measure the diameter that will allow the linner to pass into the flue, a ring welded on to stop it going too far. You may need to add a taper so the top will fit within the outer chimney, it should stop 1/2 inch below the top.

 

Stainless steel is best in which case 20 swg is ok.

 

John Squeers

[Bernie]

Thanks John,

I knew someone would come along more expertise and knowledge than I have.

[Khayamanzi]

Thanks for the help so far. I'll look into some of these suggestions.

[Rick]

Have you sealed the flue pipe to the collar with high temp silicon? This would be outside the boat i.e. above the roof.

 

Richard

[David Schweizer]

If you burn a lot of wood, you will get more tar than if you only burn coal. Hunter Stoves of Mells used to sell a compound which you put onto the burning coals of a stove which amalgamated with the tar inside the chimney and burnt it off. I don't know if they still sell it or whether it would work on a short chimney but it might be worth trying to contact them.

[Khayamanzi]

Thanks, I am actually using the powder that you put on the fire. I've only just started using it so not sure if it really works. As for sealing the Flue to the collar, I have tried packing in fire cement between to try and stop it and this has helped. Where can you get the high temp. silicon stuff from, perhaps that's what I'll try next.

[John Orentas]

Andy.

 

If it was just a matter of sealing the ends of the flue there would be no problem. There is a masive expansion and contraction of the flue pipe so one end usually the top must be allowed to float. Fix it too well and the stove can be literally lifted up off it's base causing damage.

 

John Squeers

[DHutch]

and if you pack hardsetting cement into the joints you can acttally crack case iron chiminy pipes, because as the innner pipe expands if forces the outer one to fracture (becuase cast iron is so bad in tention)

 

- i know, becuase our fule pipe has done it!

 

daniel

[Khayamanzi]

EEK! Thanks for this - where do I get the high temp. silicon seal stuff from as this is a job I need to do quick, like mail order ther sealant and do it on Saturday - you've worried me now!!

[Khayamanzi]

OK I've just ordered a tube from Midland chandlers mail order! Guess I'll spend Saturday chipping out fire cement then

 

Many thanks everyone for your help - it's times like this that this site really pays off!

Have one on me in the virtual bar at Chrimbo!!

[John Orentas]

Andy.

 

I thank you may have got the wrong end of the stick here, why do you have to do it quickly.

 

John Squeers

[Rick]

High temp silicon is probably available at your local builders merchant.

 

Don't put in a great wodge, just enough to seall across. Incidentally, it was suggested that we wrap a couple of turns of exhaust bandage round the flue about halfway down the collar.

 

Richard

[Khayamanzi]

Andy.

 

I thank you may have got the wrong end of the stick here, why do you have to do it quickly.

 

John Squeers

<{POST_SNAPBACK}>

 

 

You got me worried about my chimbly falling off into the marina!!

 

No seriously - it sounds drastic if it can cause that damage and as I'm leaving the boat over Christmas in a weeks time, I really want to get it sorted plus, that will probably be the only chance that the fire gets cold until about April!

[John Orentas]

Andy.

 

No! damage might only occur if you cament it up solidly, it is ok as it is, just messy.

 

John Squeers

[weeble]

Just revisiting this thread as I'm having a problem with tar spilling down the chinmey. Any further advice, or results from those who were talking this problem a few months back?

 

CHeers.... mike

[dor]

I used to have a tar problem.

 

My chimney fitted outside the collar, so tar condensing in the chimney would run down and onto the roof.

 

I tried fitting an internal chimney so that it fitted inside the collar, but somehow the tar still came through.

 

I solved it by finding a bit of pipe for a chimney, actually exactly 4 inches in diameter out of an old tumble drier, which fitted snugly insode the flue collar. Rivetted a ring round it and painted it and now no tar.

[weeble]

I used to have a tar problem.

 

My chimney fitted outside the collar, so tar condensing in the chimney would run down and onto  the roof.

 

I tried fitting an internal chimney so that it fitted inside the collar, but somehow the tar still came through.

 

I solved it by finding a bit of pipe for a chimney, actually exactly 4 inches in diameter out of an old tumble drier, which fitted snugly insode the flue collar. Rivetted a ring round it and painted it and now no tar.

<{POST_SNAPBACK}>

 

Hi Dor,

 

I got over tarring down the outside by buying a double skinned chimney, which works fine. The problem now is that it runs down the flue inside the boat.

 

I'm not 100% sure how the whole lot fits together! Am I right in assuming that the flue justs slides into the collar and the space between the two between is packed with fire cement? Or is there more to it than that?

Only I got a bit concerned to read of "exploding stoves"

 

If my understanding is right then I think I can visualise that what you did, thanks for the info.

 

Mike

[bottle]

I may be wrong but I think you will get more tar if the fire is just ticking over. We had a woodburner in our last house and found that running at tickover for long periods and/or damp wood inreased the amount of tar in the chimney. The chimney came out the backof the fire to a tee piece so the tar collected there and solidified.

 

As Daniel said be careful using fire cement it wiil crack the chimney if the chimney is not allowed to expand and contract.

[Derek]

Midland Swindlers do a range of stainless steel chimney liners. As long as the bottom of the liner goes inside the flue pipe the tar will burn off as it forms.

 

Derek

Edited April 21, 2005 by Derek

[John Orentas]

There is only one way to fix the outside chimney problem, you must have a double skin type with the inside one fitting within the flue pipe. This arrangement will also make the stove draw better.

 

The fitting of the flue pipe, don't use cement at both ends, it will make the whole thing too rigid, you can find that the stove is lifted bodily off it's base as things cool down and contract. Cement the bottom (rubbish stuff but I don't think there is an alternative) use silicone sealant at the top, the high temp. type if you can get it to allow things to move.

 

With all these things, if you can't buy just what you want get one made, a bonus of the exorbitant chandlery prices is that you can have things made for very little more. Always keep an eye out for a "Wesley", worth their weight in gold.

[dor]

Am I right in assuming that the flue justs slides into the collar and the space between the two between is packed with fire cement? Or is there more to it than that?

 

I just have a single chimney, that fits inside the flue pipe / collar. Any tar that condenses inside the chimney will run down the chimney and inside the flue pipe, to either be burnt, heated up enough ot escape completely or collect as burnt tar on the inside of the flue.

 

In theory a double skinned chimney should do the same, it's just that when I tried it, the tar still escaped onto the roof somehow.

 

I would also recommend high temp silicone at the bottom of the flue pipe where it joins the stove. Opening and shutting the door inevitably causes a bit of movement, especially if you have just replaced the cord seal in the door. This, along with thermal expansion and contraction, will sooner or later crack firecement. This could lead to the escape of carbon monoxide.

 

I found some black high temperature silicone sealant in Nantwich canal Centre and used that, and it has provided an excellent seal.

[John Orentas]

I keep hearing about this high temp. silicone, what temp. will it tollerate, the bottom of the flue pipe get's very hot.

[dor]

John

 

The red silicone is widespread, and for example was used at the tpo of my flue pipe in the roof collar. Whilst this is heat resistant, I'm not sure it can stand really high temperatures.

 

The stuff I use at the bottom is a black one, -it's on the boat at the moment so I can't tell you what it is called or what it is rated as temperaturewise. I will get the details at the weekend if anyone is interested.

 

I have used it to replace the fire cement in the collar on top of my Squirrel stove, between the collar and the flue pipe. It's been in for two winters now and shows no sign of deteriorating.

 

I can't say how hot the stove has got, but it has been enough to get the overheat strip on the bottom of my ecofan lifting the fan well off the surface. And hot enough to get a kettle boiling quite quickly. All a bit subjective I know, but the stove has been too hot for comfort or safety at times (leaving the bottom door open and forgetting it!)

 

I have an idea that it is rated to 400C, but that it a hazy idea at best until I check.