Need help to understand how to "connect" flu liner with insert

hstraf said:

Hello,

I have a new insert (see attached photos) that I am going to be installing into an open hearth. I'm just getting ready to install everything now, and have a few questions.

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I will try to help as much as I can, but I'm a bit new at this - hopefully Elk will chime in and correct me if I make any mistakes.

Your best source of information is the manual that came with your insert, if it isn't in English, get it translated! I would also check w/ your various local governments to see if there are any relevant codes and inspection procedures you need to follow. I've heard the French tend to be regulation prone, but I don't know about it from personal experience. It is better to find out ahead of time, as at least in the US, an inspector can make you rip everything back out to prove it's done to his satisfaction. In case of doubt, you should do what the manual and / or the inspector says. (Also note that I'm commenting based on my understanding of US codes, no promise that French codes would be the same)

In EVERY case, if what the manual says doesn't match what I say, go with the manual!

(This is a bit tricky for me, because I live in France and I don't speak French.. and there are no chimney/stove specialty stores here where I can get help since I'm actually in a tiny little village about 300 people. I have to order everything from catalogues.)

OK.. here goes:

1) The current chimney is 8x8 clay tile and goes up about 3 floors out to the roof. (I'm in the bottom floor of an apartment building.) Do I really need to install a flue liner all the way up to the top? Or can I just insert maybe 2 meters (about 6 feet) of liner up from the hearth and that is enough?

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Depends on what the manual says to some extent. Your situation is mixed as to draft, you might or might not need the full liner. A three floor high chimney (I'm guessing total height around 5 meters / 30 ft) should draw pretty well, and an 8x8 clay flue isn't that badly oversize. I'd be tempted to try the short solution first and see how it works, if it doesn't then you can pull the insert back out and go with the taller liner.

I'm trying to keep cost as low as possible (every 3 feet section of liner pipe costs about $60) and I also don't have roof access.

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Lack of roof access will be a problem if you go with the full liner, as you would definitely need to be able to put a cap on, as well as sealing the gap between the top of the chimney and the liner. Even if you are only going with the stub approach you should have some sort of cap on the top of the chimney, although whatever is there already should be OK

I understand that draft will be better if the liner runs all the way to the top, but I guess I'm trying to find the "minimum" that is necessary...

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Understood, you have a mixed situation, so if you are trying to do a minimum you will probably need to experiment as every situation is different.

Temperature here is moderate. It only gets down to about 50 degrees at night. Maybe 45 on a really cold night.

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That is going to hurt your draft, as draft improves with temperature difference

2) The chimney flu goes straight up to the roof. There is no damper or smoke shelf or anything. I can look up the chimney stack from the hearth and see the sky. When I insert the pipe liner, is there any trick to "attach" it so it stays in the flue? Otherwise, it'll just come down when I let go after shoving the pipe up.

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Straight is good, although I'm concerned about you saying you can see the sky - see my comment above about needing a cap. I'm not sure what the best approach is for holding the pipe up while installing the insert. You will definitely want a blockoff plate to seal the space between the liner and the bottom of the chimney, perhaps you could use that to give some support,

is it ok if the weight of all the pipe liner is "resting" on the insert, because otherwise I can't see any other way...

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That should be OK, check the manual. Note that if you don't go with the full liner, you will need to be able to pull the insert, block off plate and stub liner out periodically for cleaning! Also I suspect that if you use a flex pipe between the main liner and the insert you will have more trouble since the weight won't be centered.

3) At the bottom of the pipe, between the insert and the pipe.. I don't understand how to make the connection between the insert and the pipe liner in the flue. Is it possible for someone to post pictures of the different "fittings" I need to use?

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I don't have pictures, but what you want is a fitting that will slip INSIDE the collar on the insert, and that the pipe liner will then go inside. The important thing is that any creosote that forms must drip down inside the pipe to the insert, so at each joint, where one part slides into another, the big end must be on the bottom facing up with the little end sliding into it.

- The fitting to connect the smoke output from the insert (see attached photos) to a short flexible conduit piece (about 2 feet long). (I am using the flex conduit because I want to put the insert "as far to the front " of the hearth area as possible, and the smoke stack is all the way to the back...)

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Bends and flex will hurt your draft, so try to keep any bends as gradual as possible. Again, the fitting should go inside the insert smoke outlet, and onto the outside of the flex

- The fitting to connect the flexible short conduit piece to the pipe liner in the flue.

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Once again, the fitting should go inside the flex, and outside the pipe liner in the flue. Each section of pipe liner in the flue should be installed so that the lower end goes INTO the upper end of the section below it.

Continued next post,

Gooserider

Continued from above - (I hate this post length limiting function....)

The building supply store has about 10 different types of couplings available to purchase (all from catalogue) and nobody really seems to understand the differences between them. Some have “serated” edges, which I think are for attaching to flexible conduit? I don’t know… I’m hoping that if I can see a picture of the pieces I need, maybe I can match it with what is in the catalogue.

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Well, the only critical measurement is the ID of the smoke outlet on the insert, as you need something that will barely fit into that hole. Most importantly, I would say to stick with one brand and model series of pipe and couplings as they should all go together properly, but it gets much trickier if trying to mix and match as different brands might not be compatible.

I don't have a particular vendor in mind, but it might be a good idea to look for a stovepipe vendor with an english language website that you can at least use to design your setup, then take to your local store. (or order off the web and skip the local place if that is easier - I don't know what you might have to deal with in terms of Customs and such)

Keep in mind the basic rule that all connections must funnel downwards - you can visualize the setup as a bunch of nested funnels that pour into the insert.

Hope this helps,

Gooserider

hstraf said:

Gooserider said:

Keep in mind the basic rule that all connections must funnel downwards - you can visualize the setup as a bunch of nested funnels that pour into the insert.

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That is really helpful, thanks! It actually completes the piece of this puzzle that I did not understand, because I was always thinking about the smoke pouring upwards.. rather then creosote dripping downwards.

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Glad to help out, it was probably the biggest problem I had understanding the design when I first got started. Another major point that you probably won't have to worry about with your setup is that you should minimize any horizontal runs, and if you do have a horizontal run, make sure it angles up from the stove AT LEAST 1/4" per foot.

I think I now understand what pieces I need.

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Good

Once quick question I do have.. does a bead of silicone/cement need to be put between every joint of the flue/pipe? The pieces I'll be buying appear to all have "three" parts for every joint. There is the upper piece and lower piece (of pipes), and then there is a special "collar" that kind of slips around a raised part on both pipes and clamps them together.

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DON'T use silicone It isn't able to withstand the heat! At best it will melt out of the joint while emitting noxious fumes, at worst it can catch fire! Again, look at what your manual, or the manual for your particular brand of flue pipe calls for, but most typically you need to use refractory cement on the joints if there are any significant gaps. However I'd expect the factory clamps to do an adequate job of sealing between the pipe sections. You may need to put some stainless sheet metal screws into the joints between the liner and the pipe and on any joints with the flex pipe - typically three screws per joint, evenly spaced around it.

Is that clamp good enough, or do I still need to silicone/cement the pipes together?

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See your manuals

Same question for the insert's connection to the pipe. Do I just shove the bottom pipe piece into the insert and make sure it's nice and tight? Or do I need to use silicone/cement to "fill" any small gap between the insert smoke outlet and the pipe that's shoved inside it?

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Again, see your manual, and possibly the comment above about using refractory cement. Note that you aren't all that worried about smoke getting out of the pipe. If you have a decent draft, it will keep the smoke inside the pipe, and instead want to pull air in through the joint, which will cool the smoke, increasing creosote buildup and hurting the draft. Generally the idea of the refractory cement is to block the air out rather than keeping the smoke in.

Gooserider

Thanks again![/quote]

hstraf said:

Thanks again.

I agree that a manual would be nice.. but the insert came with a whole one page of "instructions". that's it. It's basically nothing more then an introduction to how fire works, with absolutely no details on installation or anything else except the measurements of the insert and minimum distance from flammable objects. There are no install instructions, "how to" diagrams or details or anything else.

That's why I'm here on these forums trying to get as much info as possible -- to fill the huge "gap" of information that the "manual" does not include.

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Ouch! That is a problem manual for sure. (I compare it to the 36 page manual for a VC stove I was just looking at...) I don't know how much info we have on what I'm guessing is an E.U. product, but is there a brand name and model # on the insert? Is there a manufacturer website or support line? What about the place the insert came from?

The geographic barrier here is a major problem... The experts here are mostly all American or Canadian, we tend not to know EU products and codes, and the connection between the chimney and insert is possibly one of the most variable between products. As such there is a gap betwen the generic information we can give, and the product specific stuff that you need.

I'm not sure just what else to suggest.

Gooserider

hstraf - is the insert you have by any chance a 'La Foyere'? I am considering one of these, though information is incredibly difficult to come by. If so, can you let me know what you think of its construction, etc.?

Thanks,

John