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Flue liner questions


Sans Souci
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We had a devis from a local wood stove supplier to get an insert installed.   He was concerned that the openeing at the top of the chimney was narrower than at the base and initially said that his flexible liner would not fit - and therefore we could not use an insert.  He then thought of using a rigid oval liner which he felt would work - at twice the price.  All of my questions and "what ifs" were met with negative shakes of the head.   My first question was why do we need a liner if the chimney was certified by a ramonage to be in bon etat.  Apparently inserts need liners (that was the extent of the answer).  I then said can the flex liner go 5 meters up the 7 meter chimney and then the smokes just goes into the chimney for the last two meters.  His answer was that the liner needed to hang onto the top of the cimney to support the weight of the liner.  If this was the only reason, I am sure that a system of cables can be used to support the weight of the flex liner with having it reach all of the way up.  He did offer the solution that if we used a wood stove, we could have a pipe that went only one meter up into the chimney and close off the base of the chimney.  That would essentially dump the smoke from the wood stove into the chimney and prevent it from rolling back into the house.  I was about to ask the inevitable question of "why can this be done with a wood stove, but not with an insert", however my head was already hurting too much from banging it against the fireplace everytime I asked a question.  Any thoughts on if the answers were factual or was he just taking advantage of an American with an "Obama for President" bumper sticker on his car.  

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[quote]He was concerned that the openeing at the top of the chimney was narrower than at the base and initially said that his flexible liner would not fit [/quote]

I've yet to see a chimney where the opening at the top was larger than the base!

If your ramoneure was able to push a standard sized flue brush right out at the top, then normal sized Inox liner should fit.

Do you burn wood, for example, in the present open fireplace and how does this draw when lit?

 

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[quote user="Gluestick"]

[quote]He was concerned that the openeing at the top of the chimney was narrower than at the base and initially said that his flexible liner would not fit [/quote]

I've yet to see a chimney where the opening at the top was larger than the base!

If your ramoneure was able to push a standard sized flue brush right out at the top, then normal sized Inox liner should fit.

Do you burn wood, for example, in the present open fireplace and how does this draw when lit?

 

[/quote]

Think you should read that again[8-)]

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I guess I should have clarified.  The opening at the top is narrower than the standard diameter of the flex tube where it connects to the insert, thus the need for the rigid, oval stove pipe.  When I questioned as to why we couldn't have just the rigid pipe for the last two meters, he just shook his head and said the issue was you needed to connect the pipes and shove them up the chimney and that could not be done with a flex pipe at the beginning.

The rammaneure cleaned and certified the chimney, and thus I assuming that he shoved his brush all the way up.  I am going to give him a call and ask him why we can't just use flex tube and also the question about just dumping the smoke into the chimney after one or two meters of pipe as per the woodstove.

We have had fires with no problem.  The last fires we had (after it was cleaned) smoked but that was the result of Souletis delivering end of the season green wood.

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Hi

The flue must terminate at the top, if you do as you suggest and stop a couple of metres short your likely to have a problem with smoke coming back down into room, simply because, with an open fire the inside of the chimney gets hot, hot air rises and pulls up smoke, this obviously pulls in cold air which draws the fire and so the process begins again. You may have noticed an open fire smoking into the room when its first lit, because the air in the chimney is cold and drops rather than rises and thus brings smoke down with it, once the inside of the chimney is hot, no problem!

What you propose is like creating a short circuit in your electrics, which you would never do of course.

You mention the opening is smaller than the opening on the top of the insert, you are allowed to fit a reducer maybe its mentioned in the instructions?

If not pop into one of the suppliers and ask if its ok to reduce it to the size that will fit your chimney.

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I have not found a chimney yet that is too small to fit a liner

I always install flexible stainless steel haut rendement for bois and the cost is circa 100 euros a meter

The advantage with a liner is that the reduced flue diameter makes the fire draw better so your get better heat and the fire is more controllable

A couple of bits of rigid pipe part way up the flue is not a proper solution

Be careful with liners as they can be suitable for only one fuel or for various fuels, always specify the fuel to the merchant if you purchase it yourself

Le Plombier

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hi ok

           Fitting an " insert " is not just a run of the mill  poel job ,first off it`s probably got a 180-250 out let on it what ever is on the top has to go all the way up , the hot box on the top has to be insulated etc, after fitting a few poels here and talking to the local artisans, if your house goes on fire , you claim on your insurance if he fits it and it goes up you claim off his , if he has not fitted a liner his insurance will not pay out ,, so he has no option.

         Dave

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OMG I can't believe some of the stuff I am reading in this thread! Firstly DO NOT INSTALL A FLUE LINER THAT IS SMALLER IN DIAMETER THAN THE EXIT FROM THE FIRE. It is true it will make it draw better, BUT IT IS AGAINST EUROPEAN, FRENCH and UK DIRECTIVES. It will induce much hotter teperatures higher up the liner, increasing the risk of a fire, not to mention your fuel will disappear much more quickly, and provide less heat.

 Can you get someone to go to the top of the chimney and measure the diameter of the hole, then find a burner with the same diameter exhaust vent?

Flexible liners rated for wood and coal are available with 5yr guarantee (liners are designed to last upto 10 yrs, but may last less) from between €20 and €25 a metre. Stainless steel solid pipes 1m long are available from €20 - €38 a metre length. All fires should have a register plate, again European regs. There are loads more things to be aware of, and all information is available on the interent, so not too difficult to do the research.

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Clarksinfrance

You obviously misinterpreted my comment

I did not mean fit a liner smaller than the outlet of the fire, the correct size flue should always be installed

What I meant was the reduced flue diameter due to the liner as opposed to the size of the chimney without a liner will result in the flue drawing better

I have to say the majority of installations I see here consist of a couple of sections of rigid flue shoved up the chimney and that is all

Le Plombier

 

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  • 2 weeks later...
[quote user="Sans Souci"]

He did offer the solution that if we used a wood stove, we could have a pipe that went only one meter up into the chimney and close off the base of the chimney.  That would essentially dump the smoke from the wood stove into the chimney and prevent it from rolling back into the house. 

[/quote]

Don't for heaven's sake go down that route! The previous owners of our house who had installed the woodburner themselves did precisely that and we ended up with a chimney fire where the soot and tar had fallen back down and accumulated on the plate where the base of the chimney had been shut off. That ignited and hey presto - showtime! Fortunately we were in at the time and took quick action so there was little damage. We have now installed an inox flexi liner (Mr Bricolage) which goes all the way from the woodburner up the chimney and out of the chimney pot where it as securely affixed. It is amazing just how much better the woodburner draws now that the liner goes all the way up.

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