Practical Advantage to Fresh Air Intake for Pellet Stoves?

briansol said:

From a scientific standpoint, if you're sucking in cold air to the house, you need more fuel to keep it warm.

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Yes, and that happens both with an OAK and without an OAK in about the same amount...

Bummer on the clean-out ....was worth a shot, eh?

The cold air from the OAK provides a denser mixture which may produce more btu's but its offset since you have colder air to heat in the firebox so the output is basically the same...

Yeah hyfire is thinking along the same lines. But I guess I should elaborate what I was getting at earlier. Seems folks don't get much past the first step in the equation here, that no OAK is wasting your heated air up the chimney and with an OAK that that colder outside air is going to miraculously pass through your home without any effect to its surroundings. Just because your channelling the cold outside air directly via an OAK doesn't mean it has no effect on the temperature of the stove and your home. I mean combustion is what is heating your home right? That's in the stove right? It has a heat exchanger right? If you fed the stove with really hot air we'd expect to get slightly warmer temp out of the stove right? The heat exchanger is designed to transfer the thermal energy between the inside of the stove and your home. Now, the heat exchanger isn't 100% efficient, so some of that is going to go up the flu. I suppose just for ballpark numbers we could say that its 75-80% efficient which is what a lot of stove manufacturers claim. Of course the rest of the system isn't 100% insulated from your home either... you have the OAK run itself, and the venting. My OAK is long, exposing several square feet of ribbed aluminum 'heat sink' (typical 2" and 3" semi rigid aluminum duct). I insulated it with 1" fiberglass pipe wrap. Even with that insulation its not nearly as insulated as the rest of my house is to the outside. And then there is the several feet of duravent, which last I checked transferred quite a bit of heat still. So you have the transfer of thermal energy through the OAK itself, venting, stove wall and heat exchanger, and the slight reduction in combustion temps. Now without the OAK, your stove is combusting hotter air to start with, which should raise stove temps ever so slightly and again 75% of it or so will be transferred back. But your pulling air now through leaks in the house, which will slightly cool the home. The slightly hotter stove and slight cooling effect of the leaks should about balance. And the two scenarios should have similar average temps. I'd still say with an OAK that you'll have minutely better average temps. But not 50% gain in efficiency as some may claim. That's as silly as putting a cold air intake on your sports car and think it alone will gain you 200HP. Not going to happen (unless your house was tight enough your stove wasn't getting enough air to combust properly). I'd wager we're talking in the couple percent range. One thing that could really effect your perception of warmth is if your chairs, couches, and whatnot are close to walls or windows where the draft is coming in. Even if its balanced out by a very slightly warmer stove, in the area closer to the drafts will be cooler. So you may have more of a temperature gradient around the house. I for one have a hard enough time trying to circulate heat around the home, so I'd rather not have the greater differential between warmer stove and cooler walls, I'll take less drafts but slightly cooler stove. I mean my stove room already runs 75-80F and the next room through the doorway (family room) drops about 10-12 degrees. If you have a thermostat or thermometer too closer to a draft, its quite possible you'd think the house was colder, and if the stove was running on a remote thermostat, then it could use more fuel. But then the average temp of the house would actually be greater. I'm all for an OAK, and its required in my case anyhow, just don't expect its going to save you hundreds of dollars a year in pellets for the same average house temperature.

briansol said:

The insert run is a bit trickier. I had scott (@swilliamson on here) come out and install a 2nd run of intake pipe up the chimney to his custom 2-story cap set up (intake on 1st floor, exhaust on 2nd floor). It certainly wasn't $50 like other's said they have done it for, but it was well worth the cost of having it done right, not a half run hack with punching holes

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I know this has been beat to death but here's my issue. Winslow pi40 insert, completely remodeled home but the old heatilator was capped off by the new roof so going up is not an option which is why the installer went out the double brick wall and up 5ft with the vent pipe. The insert burns fine but I see the sense in pulling in outside air. The Winslow is not a sealed oak setup but more just a flange, 2' inside diameter. There was a 3/4 inch hole drilled behind the stove where a gas line was at one time for a lp fireplace that I sealed, I measured the thickness of the wall and its approximately 16 inches thick. My question is if I drilled another hole and opened up the one that was there given that the insert itself is pretty sealed against the wall would the combustion fan draw the air? I'd of course screen off the outside but given the design of the oak intake would it matter if it was pulling air from a foot or so away versus spending a day drilling and chiseling so I can run a piece of liner up and basically lay it in a hole behind the fan?