Combustion Air - Alternative to drilling hole in chimney

[juliotamu01]

Hello,

I'm getting a Drolet Escape 1400I fireplace insert and intend to draw combustion air from outside rather than from the house. They have a plate that if removed on the bottom side of the insert can be connected to a 5" metal flex duct that goes through a hole in the chimney. The problem is the location of the chimney built into a brick exterior wall with not much room inside as well for the flex duct as the duct would need to be bent quite a lot to find a place in the chimney to exit. Also I would need to drill the hole with a core bit myself and would find difficulty connecting the hose. I have no ash dump that could be used for this purpose.

What about this alternative:

Opening the plate and drawing the combustion air from the top of the chimney itself. There are two flues, one capped and the other for the 6" exhaust stack. The capped flue could be replaced with a vented chimney cap where combustion air could be drawn. Wondering if anyone has ever tried this or what your thoughts are.

Thanks

 

[drdoct]

I would think it could work a little until the fire got warm, then everything would heat up and you'd have 2 drafts trying to go up. I bet it has a really hard time sucking air from up top and way down the length of your chimney. Not saying it won't, but there's a reason you don't see installations this way.

 

[snowtime]

Interesting idea. First the problems. If the chimney is drawing cold air down next to your exhaust chimney it will cool the chimney down so more creosote. Answer is to be sure you insulate the exhaust chimney. The only way I see this working without trouble like smoke in home is to run a flex liner all the way up to keep the cool make up air contained. This would be a large added expense. If you did not add the flex for the makeup air it's possible smoke will be drawn down open chimney and if you have any leaks in chimney or stove could get in house.
If you try this tell us how it works out.

 

[juliotamu01]

Thanks for the advice. I'm going to try finding an alternative.

The problem is that the fireplace is built in the middle of a wall with the wall being thick enough and the chimney only 25" deep that there is only a few inches available on the outside portion and inside portion. You could possible remove the sheetrock and drill thru to where a joist is. Since the hose is 5" diameter you would have to remove a large portion of the first stud adjacent to the chimney on one side and maybe flatten out the hose. Then you would need to make a 90 degree bend and drill another hole through the house face brick to the outside. The outside is a carport that I would also like to close in and make part of the inside of the house.

Thanks again. I'll post what I end up doing.

 

[drdoct]

Why would you go through soooo much trouble to install an OAK? I can understand if you've got a hole right there and it's easy, but to fight it seems not worth it to me.