Can someone please explain the outside air intake thing to me?

Since any stove, insert, or fireplcae naturally operates on the principle that warm air rises (up your chimney hopefully ;-P ) air is drawn in to the wood burning unit to replace the rising air. This incoming air is the oxygen source for your fire. Your stove pulls air in from the room the stove is in which in turn pulls outside air into the room through cracks and crevices in your walls, around doors, windows etc,. When it's cold out this means you're constantly pulling cold air into your house. An outside air supply is a pipe or duct which delivers outside air directly to the air intake in your stove so cold air is not pulled into your house. Expense varies depending upon how hard it is to run a pipe from an outside air source to your stove, insert, or fireplace. If it's at all feasible and your stove or insert is designed to accomodate one, I thinks it's very worthwhile and in general not really normally all that expensive.

do a search on it.

In theory could a fireplace "cleanout" - a trap door that dumps ash to a cleanout door in the basement- provide the conduit for outside air, albeit from the basement?

gibson said:

In theory could a fireplace "cleanout" - a trap door that dumps ash to a cleanout door in the basement- provide the conduit for outside air, albeit from the basement?

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thanks for asking the question. This is exactly what I was thinking of doing with our insert.

Theoretically, your basement is part of the house envelope.
Your basement should not have outside air in it any more than your upstairs should.

Should doesn't mean it won't work, just that the whole concept of <<outside air means <<outside air.

In my fireplace, toward the front of the firebox (just behind the doors/screen) was a steel box rising up from the floor. It was about 3'' high, 6'' wide and 3'' deep. It had a adjustment lever as well. It penetrated down into the firebrick floor and connected to a channel that ran under the fireplace toward the rear/outside chimney. If you looked outside around the same level, three bricks were installed vertically and spaced between them to allow air to enter the channel. This was the outside air intake for when the fireplace was in use. It had to be removed to get the insert in and left a clean rectangular hole in the floor after it was gone.
Before I installed my insert I reviewed the installation manual and it showed the underside of the insert and a knockout that can be removed to accommodate an outside air intake. Usually a duct would attach there, but since I was installing an insert, that was not an option as it sits directly on the floor. After some measuring, it was determined that the hole in the floor of the firebrick left from the removal of the steel box lined up with the knockout in the insert pretty well so I decided to tell the installer to go ahead and knock out the blocking plate and slide the insert in.
There is a kit that is supposed to be installed in this application to divert the intake air from the room to the knockout/outside air intake but I have yet to install that. I'd imagine after that's in, I will be getting all the air for the fire 100% from outside, but for now knowing that a good deal of it is probably coming from outside now is OK w/ me. It's probably a mix of both at this time. It will probably be great if ALL the air needed for the fire was coming from outside and not from the warm air inside my house, but that will have to wait a while.
If anyone knows of a reason why I cannot or should not operate it in this condition because of any adverse results (other than a 1/2 and 1/2 mix of air), please let me know if this is a problem (like the stove itself does not work optimally or it is dangerous to use it this way).
Sorry for the long post but I thought what I already went through was worth sharing. Thanks