13" Triple wall stove pipe

A chimney SYSTEM is designed and tested using only approved parts. You are taking a risk by modifying any chimney system. Your best bet is to try and find a label on a section and order the same type. Or if you can't find the info, the next option would be full replacement.

If it's air-cooled (as it sounds like) then you aren't supposed to block the gaps between the walls. Airflow is part of the design. Majestic has a chimney like you describe, it's their "type S" or "S8" chimney. Not sure where you can buy it.

NOT spose to use air cooled chim for wood stoves

yogabill said:

humpin iron,

Could you expand on your answer about why air cooled chimney is not recommended for wood burning stoves? I am a handyman and not a chimney specialist and would like to be educated.

thanks
B

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From chimneysweeponline.com....

Air-cooled metal chimneys, which are designed to vent manufactured zero clearance fireplaces, actively cool the smoke. While cooling the smoke is a good idea when venting the super-hot exhaust created by zero clearance fireplaces, which send most of the heat from the fire up the chimney, it is the worst possible method for venting the already-cool exhaust from today's super-efficient airtight stoves. For this reason, code authorities have outlawed the use of air-cooled chimneys to vent airtight wood stoves.

An insulated chimney liner makes an air cooled triple walled chimney into an air cooled triple walled chimney chase though. Blocking the air flow makes it into a triple walled metal chimney chase.

humpin iron said:

NOT spose to use air cooled chim for wood stoves

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That's a slightly overbroad statement. My BIS Ultima (EPA woodstove in fireplace form) has 3 approved chimneys, one of which is double-wall air-cooled. Both the stove and the chimney are made by Security, and are an approved combination; it's probably true that you can't use that air cooled chimney for a non-Security (or Lennox) stove.

My Majestic WMC42 (a non-EPA fireplace) came with the aforementioned "type S" triple-wall air-cooled chimney, which is the rare AC chimney that is HT2100 rated. Majestic is a CFM company, and that chimney is also used on some of their EPA fireplaces.

So there are specific cases where AC chimney is approved for specific EPA stoves, and the customer's current setup might be one of those. (Not clear if we're talking about a non-EPA fireplace, an insert installed in a non-EPA fireplace, or an EPA fireplace.) It's true that AC is more likely to have creosote buildup, although on my Ultima it amounts to a few cups of dry powder every 2 years.

There's also the ever so slight possibility that this person is burning not-so-dry wood.

jeff_t said:

There's also the ever so slight possibility that this person is burning not-so-dry wood.

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Agreed. I would suspect user error before a performance issue.

As a purely practical matter I don't know how you would connect insulated chimney to air-cooled chimney. The air-cooled is probably some sort of snap connector, and insulated usually has some sort of twist connect.

There is insulation wrap for chimney liners, but I don't know if it would do much here. The design of air-cooled pipe generally allows outside air to circulate between the layers, and in a triple-wall type it doesn't seem like insulating the other layer is going to affect the temp inside the inner pipe much.

Disco- the units you cite are classified as fireplaces, not air tight wood stoves and yes I'm very familiar with the BIS, I installed one of the first 50 ever made. You CAN NOT mix air cooled and insulated chimney. They were tested and approved with those chims. Wood stoves are not approved with air cooled chims, in the 70's nobody knew better......that was 35 years ago.
The proper way to "fix" this problem is to pull the entire chimney system and replace it with the proper insulated system. Big bucks but it is the proper way to do it.
Yoga- not being disrespectful here, but you may be getting in over your head, I'm very sure your in over your liability ins. You can not modify that chim or add any parts other than the original mfg parts (exact replacement parts). If you do you will own ALL the liability for that chimney forever. Just to give you an idea, I met with my ins guy today, my liability for this kind of work costs my company $19,000 per year

humpin iron said:

Disco- the units you cite are classified as fireplaces, not air tight wood stoves and yes I'm very familiar with the BIS, I installed one of the first 50 ever made.

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So are you saying it's basically a loophole that some EPA fireplaces are approved to use air-cooled chimneys? Because there's not really any substantive difference between EPA fireplaces and EPA woodstoves; the former are just woodstoves in a zero-clearance shell. I guess the lack of connector pipe on the fireplace makes air-cooled more practical, as there's usually a special adapter or fitting where the bottom of the chimney connects to the top of the fireplace.

In any case I agree you can't mix air-cooled and insulated, practically or legally.

pen said:

It's my understanding that the air cooled was used for the exact opposite reason that you'd use insulated pipe. Insulated pipe keeps flue temps warm while also offering reduced clearances. I think their concern with some of these fireplaces was that they'd send so much heat up the chimney that insulated pipe couldn't keep the temps down for clearances on the outside so their solution was to used air cooled chimney to keep clearances low.

If that makes sense. :-S

pen

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I think that's what Tom was saying.