Holloween day was the first burn for us this season. I usually don't fire up the stove till it gets consistently below 50* outside. This is our first cold snap that is keeping us in that range. I swept the chimney, put a couple new air tubes in, and tore the stove apart cleaning it and checking it over. I replaced all the firebrick and installed an outside air intake to help equalize the pressure to the stove. It would almost always dump some smoke into the basement (and get through to the rest of the house) upon a cold start. The reverse draft is caused by an outdoor chimney that goes 33' up the outside of the two story house. The intake to the fresh air feed is on the west corner of the house where there is almost always a breeze or wind coming up the hill so it should almost always be positive pressure compared to the top of the chimney. It seems to have worked as intended. When I started the fire, ZERO smoke dumped out of the stove without having to pre-heat it like usual. This is a first on a cold start. I'm very happy that this worked out and seems worth the $$$ and time it took to put it in. Borrowing a good hammerdrill from work made the installation go pretty easy. Getting the 5" intake duct through the 12" block wall was the most difficult part. The house plans showed all the positions of the re-bar and solid concrete cores so I could avoid those.
I thought about it, but since it will just drip onto the basement concrete floor, I decided to not worry bout it. After I got the fire going it dried up anyway. It's been going now for 5 days and all seems to be working out well. This thing heats the whole house pretty well, although I wish I had a big a$$ Blaze King sitting there instead to get longer burn times. This set up does well down to 20* or so, but but at that point I really need to feed the beast every 3 hours or so to keep it up in the high heat output range. I'm working hard on getting ahead of the 3 year plan so the really cold months are all heated with well seasoned sub 20% locust, iron wood, beech, and oak. I still have a lot of EAB standing dead Ash in this year's mix. Thanks for the suggestions. I'm always looking and listening for better ways... and this is a great place to find them.
That's the old "Better'N'Ben's" air-tight smoke dragon from the 80's or so... It was in one of the houses we flipped back in the 90's and we had kept it and heated with it at our old house and this house till I decided to get an EPA stove that gives us the same heat with half the wood cuttin'... It was kinda nice in many ways. I only fed it 3 times a day and it kept us pretty toasty. This new one is not a cat stove and to keep it in the higher heat zone I have to feed it much more often... But my shoulders like it that I'm not out there cutting twice the wood... I would like a monster size hybrid or a Kuma furnace, but till I hit the lotto... We pretty much broke the budget when we built this place in 2007. Happy wife, happy life...
I may be mistaken, but is that a fresh air supply that runs from behind the stove, near the floor, then vertical rise above the stove and out the masonry wall? If so, you should look into reverse draft issues and the safety issues they present. We do not recommend F/A at any point in time rise above the floor of the stove. In high wind instances, low burn rates, draft can be reversed. In such instances, the chimney becomes F/A and the F/A becomes the chimney. Where F/A intake is kept below the floor of the stove, such as through the wall behind the stove or a crawl space, the instances of reverse draft are never really an issue. However, when the source is derived higher that the top of the stove, well that is where it's difficult. If your install is in a basement, perhaps a daylight basement, you could then run the F/A source along the floor to the ground lever exit. Search NFPA 211 Standards for Chimneys, Fireplaces, Vent and Solid Fuel-Burning Appliances. I only post this in concern for safety. Stay Warm! BKVP
BKVP, thanks for the info on that. You are correct that the OAK intake is 4-1/2' above the floor of the stove. The only access I have at floor level is the door itself. Both sides of the door outside have retaining walls with the slope rising quickly away from the doors. The fresh air access is on the West (prevailing wind, high pressure) corner of the house. The house is oriented so the four corners of the house are at the four corners of the compass. The chimney top is approximately 35 feet above the air intake and 39' above the floor of the stove. I did read extensively on OAK installs and thought about this issue when installing it. A high wind situation coming from the East may cause a low pressure condition at the intake compared to the top of the chimney but that would also have to overcome the draft of a warm/hot stove with 35' of head (vertical lift). The potential for a reverse draft does exist under some unusual and hopefully rare conditions that you mention. I will keep an eye on this for any indication that reverse draft has occurred or is immenent. I've been watching the weather and want to babysit the stove during a East wind to make sure no dangerous condition can take place. This OAK install is new this summer, but the stove has been in operation for years. When I was setting this OAK up, I purposely used only metal components for the fresh air intake system. It only touches the concrete block wall and the screen / hood outside is all metal and at least 3' from any flamable substance. I am thinking that in the instance of a reverse draft, I may get some smoke being pushed out the intake hopefully only temporarily if at all. I do have dampers in both the chimney and the air intake that can be shut down to limit the fire in this possible scenario if it persists. I'm thinking I have the bases covered, but I am not always as smart as I think I am... Thank you for voicing your concerns. I do appreciate you making me think more deeply on this. We do have a whole house smoke alarm / CO / CO2 detector system that is kept up to date. I agree with safety being a high priority. I will definitely keep an eye on it whenever we get an easterly wind. It will be revised or removed at the first indication of any issues. Maybe I could / should install a cutout with damper so I can use the OAK during cold starts where it has proven it's worth, then flip the dampers so it pulls from the basement floor inside during normal operation. I have never gotten a reverse draft pushing smoke into the house after the initial cold start before, but I realize the OAK does change the pressure dynamics. It sounds like you know your way around chimneys, stoves, and venting. Your knowledge and advice are always welcome. At our old house where we had a masonary chimney, I made my own chimney cap with an airfoil bump on the bottom of it to enhance the low pressure zone at the top of the chimney when the wind was blowing to prevent back drafts during gusty conditions. We would occasionally get a puff of smoke in the house. That was also a basement install without an OAK but the masonary chimney was only about 18' tall. That chimney cap worked very well and we never had any smoke puffs in the house after it's installation. It was kinda like a 360* upside down airplane wing. I even did some testing in the barn to make sure it assisted in pulling air up out of the chimney using a fan and an anemometer to measure the flow through a chimney liner so I could optimize the height of the airfoil cap from the top of the flue liner to get the most pull of air through the liner. I've looked for a chimney topper for my stainless steel chimney that was designed like that but I haven't seen any. Thanks again, Monte
Just found this from Luxury Metals that is interesting and would also make the back draft more improbable. This should increase the low pressure zone at the top of the chimney to offset the low pressure zone created when the AOK intake is on the downwind side of the house. Wind Directional Chimney Caps - Steel Rotating Wind Blocking Caps
So if that cap pivots and gets enough build up, it could seize in the wrong direction. As for OAK, if you ever, Lord forbid, had an insurance claim, they will go straight to NFPA211 and deny the claim. As a manufacturer that deals with hundreds of dealers, regulators and competitors, stories abound. And a claim denial is certain.
I agree with the mechanical chimney cap being a point of failure. That is probably why I passed on it years ago when I did the airfoil cap. I hadn't looked at the OAK from the insurance end of it. HMMM!!! I rarely use the side of the double door that is closest to the stove. I could put a hood on the outside of the door with a flex link along the floor. I'm not a huge fan of the flexible where it is exposed and could be crushed. I will get it figured out. Thanks again for the feedback.
I moved the retaining wall over 8 inches so I could have access to a spot on the block wall that the house plans show no rebar and fill. I will move the OAK over there to ensure insurance issues are not gonna bite us. It will be a level shot out of the back of the stove via a 90* elbow and straight to the new hole. I started drilling out the 6" hole for the 5" intake and hood. The house blueprints showed no rebar and fill at this point, WRONG... but I'll get it. Seems like I get to do everything the hard way...
I was in the same boat as you with the daylight basement install. Masonry walls on north and south sides of the house. My Ideal Steel is in the northwest corner of the basement and I had to go through the masonry wall for both chimney and OAK. My OAK goes through the wall at 14 inches from the hearth floor and is around 8 inches higher than the OAK inlet on the stove. I used a 90 degree 4" piece of exhaust pipe and fitted it with white ABS and screening to keep critters out. My OAK is below any exhaust point on my stove and thought the risk of a reverse draft would be very minimal. I'm watch this thread to learn....
NVhunter, I burned all last winter with the OAK the way it was originally installed at 4-1/2' above the floor of the wood stove. I had zero issues but I'm not encouraging any "not to code" OAK installs. My chimney is very tall and I have a lot of draft to start with and the only reason I installed the OAK in the first place is the initial cold starting of the stove that would usually dump smoke into the house when the chimney was cold (I would normally pre-heat the chimney with my propane torch, PITA). I normally don't do many cold starts each year, but I absolutely HATE getting smoke dumps in the house. BKVP got me thinking about it and even though I'm pretty sure I would never have an issue, I was able to come up with an alternate solution for a proper install. I have to finish the OAK / retaining wall move later today and will post some pix when I get done. In my mind, over 30' of hot chimney pulling draft and using all metal OAK components with it being well over 4' from anything flamable, PLUS dampers in both the chimney and OAK allowed me to sleep well. In todays world of insurance companies looking for any reason not to pay on a claim pushed me to figuring out an alternative solution that leaves no "code violation" outs for them in the crazy improbable chance of a home fire. Thanks again BKVP for keeping me from being too smart for my own britches...
Finished up the OAK this morning. I still have to move the stone back over against the retaining wall. The outdoor intake is now at the same level as the intake port on the rear of the stove. You can see the old intake in the wall above the light switches. I'll fill that with rags and tape over it to ensure no air comes in. I may find a use for it later. I still need to re-cut the cap stones and pile the rock up against the wall.
I'll have to keep an eye on it and keep it clear. I usually set my ash bucket outside the door right there and it's usually "warm" and keeps the snow melted away from the door except for some really cold snaps. It would have to be some pretty wet heavy snow to block the air completely. I'm sure other OAK installs have to deal with the same issues. I'm liking it because it keeps the stove from dumping any (at least very little) smoke into the house on a cold start. With almost 30' of cold chimney outside of the house envelope, it has a reverse flow when cold without the OAK. With the OAK, I get the papers, kindling, and a few splits arranged in the stove, light it and close the door and it pretty much takes off. Way better than spending 20 minutes with the torch warming up the stove to prevent the smoke dump. Once the chimney gets the least bit warm, it starts pulling draft like a freight train. So much draft I have to use the damper on the stack along with shutting down the primary air to the minimum stove setting.
Build a plywood box that is 24" long and 12" wide with open ends. drop over the top and you likely will have no issues. A guy in Wis. showed me his same setup from a daylight basement. His stove just wouldn't burn! He tried all sort of stuff. Then his kid shoveled the snow away from the house and yup there was the culprit!! He made the plywood box and it had a handle on top. He simply lifted it up once a day during heavy snow and it kept every thing clear.
