Easy modification to Outside Air Kit provides a shutoff valve to stop cold air when not in use

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ReedMikel

New Member
Oct 22, 2016
12
Monticello, NY
I just bought a new Napoleon 1100C wood stove and the first few fires were easy to start and worked well. One time though I started getting smoke blowing back into the room while the door was open a bit during startup. I quickly realized that my basement "Wave" ventilation exhaust fan was running, so ran down and shut it off. That stopped the smoke...
I realized I would probably need an Outside Air Kit (OAK) so that the combustion air would be coming from outside the house as opposed to inside. I had ordered an OAK with the stove, but initially did not install it based on the advice of the installer. He seemed to feel that introducing cold air into the combustion chamber was somehow inefficient, plus I had a log cabin home - and did I really want to drill thru a log? But after the smoke incident, I decide to install the OAK myself. I figured, worst case I could just fill the hole with insulation and I'd be back to square one. Then I thought - wouldn't it be sweet if the OAK had some sort of shut off valve right as the 2" metal flex pipe entered the house (at the exterior wall). I'd be able to test if using the OAK actually helped situations like the negative air pressure/smoking incident I experienced when basement ventilator fan was running at start of fire. I could also monitor temperatures throughout the house and get a sense of whether the OAK prevented cold air from seeping in cracks around doors, windows etc. My cabin was built in 1985, and doors and windows are original and DO leak.
Interestingly, when I called Napoleon to ask why they didn't offer some sort of shut off valve option for their OAKs, the guy had no real answer, other than to say ""well, what if you sold your home and the new owner didn't know about the OAK shut off valve?". That's about as lame an excuse as possible, as if I forget to open it, my stove will simply draw its combustion air from inside the house - as if no OAK was ever installed. No harm done.
So, since I could not find any OAK shut off valves being sold online over the Internet, I decided to make my own. But what to use for the shut off valve? Then I remembered seeing what is called a "gate valve" in the interior cabinet space of my hot tub. Gate valves are used to isolate water pumps so one does not have to drain the entire hot tub when doing a pump replacement. I easily found one on Amazon (see link below) for $7 and ordered it. It consists of 2 female ends that accept 1.5" PVC pipe, but conveniently have ODs slightly larger than 2.25". I removed the four machine screws/nuts that hold valve assembly together and replaced them with 4 wood screws, which I then used to fasten valve to the exterior wall (nice having logs to work with - no sheetrock anchors needed). The 2.25" OD of one side of the valve fit snugly into the 2.375" hole that I drilled thru my exterior wall for the OAK's flex metal pipe. The trickiest part was getting the OAKs 2" flex metal pipe (coming from stove) secured to the other female end of the gate valve. I used a 2" hole saw, heated it (outside) with a propane torch, then brought it in and used it to elongate the gate valve's female end so that the metal flex pipe would fit in snugly. Once I got the metal pipe attached to the still hot PVC female end, I used a hose clamp to really secure it. Not really necessary, but I put a bead of silicone where metal pipe meets PVC. See picture below...
Now for the legal crap: Perform this only if you are a handy DIY'er, don't burn your house down with the torch etc. :) Don't create too many fumes when melting the PVC - open a window. Don't blame me if you have a problem. It worked beautifully for me...
Here's the final product (not sure why it's rotated 90 deg? The gate valve's handle points to my floor):View attachment 189739

Outside Air Kit with gate valve.JPG
 
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Nice job. Great idea on the gate valve. I wish I could put one on my OAK but the stone chase for my FP30 is going to cover up the access to it.


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I hadn't found any dampered outside air kits when I searched (mostly on Amazon) - good to know there's a few. But the manufacturer you linked only has one that goes down to 3". I need 2" for my Napoleon OAK. Plus, their 3" damper is $99 - mine cost $7 (plus maybe $15 fr new hole saw if I'm too lazy to clean it after using it to melt the PVC). Interesting that their dampers go from 3" to 5" - that's a whole lot more air than my smallish Napoleon 1100C wood stove :) I imagine whatever behemoth stoves that would need 4" or 5" OAKs must consume a whole lot of air for combustion. All the more reason to use an OAK on those monsters...

Initially I figured it wouldn't need to be insulated because I can now shut it off when stove not in use. But I guess it still makes sense to insulate it? If it drips, it's only landing on tile, so no biggy. But I guess there's no need to have a freezing cold pipe in the room when I am using the stove...

PS. When you use the heated 2" hole saw to enlarge the female PVC connection, you'll probably end up with a useless hole saw when you're done. It left a lot of plastic residue. But a new hole saw is under $15 :)
 
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