air for the wood stove

Close to stove, PVC pipe through wall. Elbow inside with pipe pointed up, elbow outside with pipe pointed down. Screened end. Heated inside air rises. Cold outdoor air drops. This configuration prevents unwanted air exchange. Pipe through wall will not leak warm out, or cold in unless pulled in by stove. (or mechanical draft caused by exhaust fans) Better to have the draft close to the stove leading directly to intake than through the house. This also prevents the stove from pulling air towards itself defeating radiating heat away. A mixing box or a way to warm outside air in the basement is fine, but the vent providing air should terminate close to the stove intake.

I would use 3" PVC, terminating lower than the stove.

I had a Goldilocks mobile home approved stove that pulls outside air up through the pedestal base with factory 6 inch from under the home. It was a kit supplied by Dura-Vent. In a conventional stick built home, I connected to 3" PVC under the floor in the basement. Since the stove pulled all it's air through this pipe, on extremely cold nights, there was so much cold air going through the pipe it would frost up with condensation in the basement. My dehumidifier doesn't remove any moisture during winter months, so there isn't much moisture in the air down there all winter. Below zero, the pipe would get ice on it, and drip during the day, so I fashioned a gutter under it and dripped into a bucket.
That shows how much air the stove would pull through any crack it could anywhere in the house. Made me a believer in an outside air intake.

It's easier to explain using the word "pull" air in, but keep in mind this is an incorrect term used for explanation only. The expanding and rising products of combustion moving up the chimney creates a void, or negative pressure in the stove. Atmospheric air pressure is what pushes air into the intakes of the stove, as well as through every inlet it can find outside the home to equalize the pressure. It doesn't matter if it's in a room far from the stove, it has the same air pressure outside pushing in th ebuilding far from the stove. You just don't want this cold air moving through the house toward the stove causing drafts.

If you use an A/C all summer, and don't want warm humid air migrating in, a 3" sewer termination valve for an RV (sewer dump) works great for closing it off. I was in the RV business and had them in stock, I guess most people would stuff a rag in the pipe for the summer.

The link didn't work, but it's the black dump valve on any motorhome or travel trailer that dumps the sewer. Theye are available in 2" and 1 1/2" for gray water (wash water) on an RV as well. Walmart may have the replacement valves in the RV section.

If you put a 90* el on the horizontal pipe about floor level facing down outside, (rain water can't come in) and face it upwards inside, the warmer indoor air will want to rise, not drop through the pipe. Not too high inside to keep it as close as possible to the stove intake. You can simply put a cap on it inside for the summer. The only air that may come in is if it's on the windward side of the house, but a fine screen over the end, and the two elbows diverts the wind fairly well. It should only draw in as needed. You will feel cold air coming in if you turn on a bath, kitchen, or clothes dryer that all exhausts outside. A gas water heater, furnace or unvented heater will also use this air source unless one is provided for them. Anything that uses indoor oxygen will benefit from it. So you may feel a slight draft through it for many reasons. It's a necessary evil of burning or exhausting indoor oxygen.

No matter how much you're tempted to use the pipe as a urinal DON'T DO IT ! Even flushing with water, the saturated ground outside draws right back in ! Guys are pigs, what can I say. Maybe it's only the ones that burn Fisher's. :red:

We used to call them "Elephant Trunks" when I installed gas equipment. I would always install them for a gas water heater or pool heater that requires fresh air in a hot tub or utility room area. Depending on the BTU of a pool heater, a couple 4" inlets terminating next to the burner intake to prevent chlorine vapor in the air from being drawn through the burner tubes was another benefit. Super corrosive atmosphere even to stainless burners.