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Chimney & Fireplaces/Sealing, Insulating Chase.


QUESTION: I'm remodeling my Majestic Fireplace to add a raised Hearth that was originally installed as new construction at floor level. I'm in the Chicagoland area so it can it quite cold. I always had cold air around the fireplace and want to correct this issue with this remodel. My Chase was not Insulated and had no outside air into the fireplace. I'm putting in a ceiling and insulating the Chase. I will drywall with 5/8". I'm adding outside Air intake and Glass Doors. My question is since this area of the chase will be sealed tightly. Even around the Flue Firestop.

Will that part of the Chase need outside air for the 3 wall Flue to vent properly?
My Air Intake will be dampered to shut went not in use. I was thinking that I might need to divert some of the intake air into this part of the chase.


ANSWER: Hello John, all Pre Fab fireplaces  must be installed to the manufactures install instructions (even your building department will tell you this) so you much install the Majestic model you have any thing else could void the UL listing and cause a fire.

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I am Re-Installing to the Installation Instructions that came with the fireplace. Keeping air gaps as noted. The instructions even note the outside chase should be insulated in cold climates which the original builder did not do.

The reason I'm asking the question is now that the Insulation and Drywall is up in the Chase and knowing how air tight it will be once I close it with the interior wall.
There is no mention about adding an air vent for the Chase (Which would somewhat defeat the purpose) in the instructions so I was thinking I'm missing something.

I was just wonder how does the 3 wall flue get air flow in the openings at the top of the fireplace where the flue connects for the outer 2 flues? Does air come down the Outside flue and up the Middle flue?

I guess I'm curious of how it's suppose to work.

ANSWER: Welcome back John, the 3 pipe flue is an Air Cooled chimney, it dose not circulate the air (that I know of)  up and down the pipe as the pipe heats up each section has air rising in it, and it where that air comes from, I am realy not sure, have you tried calling Majestic?
Sorry wish I could be of more help

---------- FOLLOW-UP ----------

Majestic doesn't have a customer contact number. Your directed to a supplier. Which I used to get a new section of 3 wall flue pipe. That supplier didn't seem to know details of how things worked as they passed other questions to an installer they worked with. I decided to use a forum to answer other question if they came up. Which this one I'm trying to get right. I do see in Canada a Air intake for a insulated Chase is required. My local building dept has no info about the subject.

My search continues...
Thanks for your replies.

John, I guess I should have started with, I have only installed one of this types of chimneys in my 32 years and it was a direct replacement, as far as insulating the chase you are going to have to follow what you have, if you are not in Canada, I would not install that vent.
Basically, the way I read some of them is the Chase should be built as if it is an interior wall, with insulation, steer rock and taped, then close it in with a good chase pan on top.
Hope t his helps
also I have found a Majestic Owners manual (not sure if it is for you unit) that I have attached  

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James Ball


I am a chimney sweep with over 22 years of experience, CSIA certified and member of the NCSG, I can answer questions about smoky fire places, wood stoves, and heating units (boiler and furnace chimneys) do you need a relining? A cap? And much more


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Chimney Safety Institute of America, National Chimney Sweep Guild

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