Fireplace "vent tube"? Can someone tell me what this is?

Old 01-11-13, 12:23 PM
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Question Fireplace "vent tube"? Can someone tell me what this is?

I have included two attachments (one showing the outside and one inside) of my fireplace/chimney with a "venting tube" (at least that is what i am calling it).

First, can anyone tell me its proper name, and what its purpose in the fireplace is? I assume it has to do with venting air into the fireplace. Our house is over 15 years old, and I have not once used this "vent".

The bigger problem is the condition of the vent. The door on the vent is not at all sealed when closed, and it is allowing cold air in winter and hot air in the summer into the house. The indoor door and frame is also deteriorating quite badly, and looks to be falling apart, I assume from over 15 years of fires.

I was wondering if I could plug the hole completely, using fireplace mortar. But without knowing why it was put in, I am wondering if there could be any negative affects of plugging the hole? In a perfect world, I would like to remove the metal frame inside, and then plug the hole, but not too sure if that would be doable.

Any thoughts on its purpose?
Any suggestions/comments on simply plugging the hole?

-- Jim
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Old 01-11-13, 12:37 PM
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Well it does serve a good purpose in that it allows make up air from the outside to feed your fire rather than taking it from your living space. That is good. I do understand about the drafty conditions it presents. It is not the best set up I have seen, but it works. Would there be any way for you to tap the seams of the top and bottom "slide" to make the door more efficient when it closes? I would not eliminate it, as you need that air. Glass fireplace doors may help, but I believe if you tightened up the door slides a little, it would help considerably.
Old 01-11-13, 06:48 PM
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The manual for mine calls it an "Outside air intake kit". Mine is a heavy cast iron grate in the floor of the firebox right behind the glass doors. Sliding open the grate opens the door at the end of the intake pipe. Seems to work very well as long as the little lever that connects the grate to the door doesnt get dislodged.

With a set of well-sealed doors I dont feel any drafts with intake open and doors closed.

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