How many of you are using or "Need" an outdoor air kit

[Simonkenton]

from the link provided by pigc:

" It turns out that the most consistently reliable place from which to take combustion air is the room where the appliance is installed. Forget about outdoor air supplies as a way to make wood stoves and fireplaces work better or be more efficient"

I have a wood stove, and a fireplace pictured at left. For the wood stove I do not use outside air, can't tell any difference in the house. The wood stove draws fine and doesn't smoke up the house. A wood stove just does't use that much air.
But, for the fireplace it is a different story. When the house was new, I started off with a 5x5 inch outside air intake, it is right in the middle of the hearth. When I had that fireplace roaring, cold air was sucked into the house from every nook and cranny. This is a well built house and is pretty air tight, but still, air was coming in the dormers upstairs, as well from other places. On the other hand, the fireplace worked fine, but there were some cold areas, I like to lay on the sofa upstairs to watch tv and could feel that cold air coming in that dormer.
So, I installed a big outside air intake, right next to the fireplace on the left side. This grate is 6x14 inches. This was just what the doctor ordered, the two outside air intakes provide plenty of air for the fireplace. No more cold air coming in the dormers.

However, as the link correctly stated, using or not using outside air had no effect on fireplace performance.

 

[fox9988]

I need an OAK. I built my house myself 3 yrs ago. Blown cellulose in the walls and attic, house wrap, lots of caulking and spray foam air sealing. I've never had a blower door test but when an exterior door is opened or closed, all the bedroom doors in the hallway rattle because of the pressure change. If one bathroom exhaust fan is on, the check valve in the other rattles. The exhaust fans, or especially the dryer, will make the stove draft very sluggish and would probably reverse the draft if trying to light a cold stove. The dryer will pull smoke odor from the chimney during the summer, if we don't crack the window in the laundry. The stove drafts perfectly if there ins't something running, pulling a vacuum on the house. We crack the window if the dryer is running, year around. I need an OAK.
If I were building a new house, I would install an OAK. Especially if I were wanting a tight house. You don't have to hook it up if you don't need it. I will have to penetrate a brick hearth and stone exterior to install one now. It would have been easy to do during construction. An OAK can be ran under the slab if the stove isn't on an exterior wall, or plumbed into the crawl space.
Why don't dryers have an OAK?

 

[Wood Duck]

I have an OAK that was required by code due to the age of my house. The house is leaky so I am sure I'd be fine without it, but that wasn't an option because I wanted to keep the house up to code.

If you think your stove won't start well with cold outside air, start it with the door cracked, then shut the door (and switch to outside air) once the fir gets going.

 

[Dieselhead]

I ran my bk without an oak since sept. I installed one last week and notice the rooms furthest from the stove are warmer, also the hallway by the front door is where my couch backs up to. I'd always feel the gentlest cool breeze coming past me going towards the stove. For the last week with some temps in the single digits, Even a small blizzard came through, those rooms are warmer and the breeze has gone away. I haven't noticed any changes in the humidity claim though. I held up a sheet of paper to the combustion air inlet when the stove was going and the draft held the paper in place. That air has to come from somewhere, which is going to be the outside. Dryers run for an hour, my stove runs for 24/7. That puts the house in a vaccum and outside air is going to infiltrate.

 

[FTG-05]

Put me in the camp for "needing" an OAK. Why? Because I collect, cut, split, stack, transport, restack (at the day supply area), start and feed the stove and do the ashes. Last thing I want to do is more of it just so I can reheat air that should have already been heated if it hadn't been sucked up by the wood stove.

Why would anyone want to heat air twice?????

 

[jotul8e2]

I too built my house. I too personally supervised or installed my insulation and sealing. I too made every effort to control air infiltration. I bought the ductwork and all to install an OAK. It is still in the bag on a shelf.

My house has five exterior doors. Do what you will, they are not perfectly tight. I have four attic access doors; same issue. I have five bathroom vents and one kitchen range vent (with an eight inch duct to the outside) and the downdraft dampers are only a slight impediment for the stove's makeup air. In fact the range hood does not even have a true damper. All in all there are just too many places for air to come in.

 

[Poindexter]

Good selection of experience here. Throwing in my two cents for future search button users.

I live in a 1980s construction home now. I have put a great deal of effort into air tightness, weather seals, air leaks and etc. My house is still leaky enough, intentionally, that I don't need and OAK - and don't want one. I would rather burn a little bit more wood and not have potential mold issues to deal with when it is time to sell. Air turnover is a good thing.

My wife and I are looking forward to selling our five bedroom house pretty soonish as the last of the children start college. No need to heat five bedrooms for just the two us. We are looking at super efficient building techniques pretty hard. The consensus among local to us home builders is figure out where the OAK should go, build without it, light the stove and see if you need it. If you do need it, you already have a free space in the plans that should exist in the as built to install the OAK.

FWIW we are looking at R-60 walls, R-80 ceilings and tight enough seals to require an HRV system.

Masonry heaters, I think, should have both an OAK with a damper in it, and a flue damper so once the rocks are hot all through flow can be stopped, trapping as much heat as possible inside the envelope.

 

[DickRussell]

Another vote for the OAK, if your house is built to be exceedingly tight. Be careful of advice to skip the OAK if it's based on a house built tighter than older construction but not really tight by blower door measurement. Many houses thought to be "tight" actually leak a surprising amount of air when it's bitter cold and windy outside. Even a house verified to be actually tight by blower door test (under 1 to 1.5 ACH50 is a good result) will leak enough air to support a woodstove once it's running, as long as there aren't other depressurizing exhaust devices running, such as a dryer or range hood, and perhaps even with one of them running (unless it's a mammoth range hood built for a restaurant, exhausting 1000 CFM or more). Lighting off a stove with either of those going can result in downdrafting and filling the room with smoke. Once the chimney is full of hot flue gas, the draft becomes another exhausting device and can compete for outside air sucked in through the myriad leaks in the building shell, especially if an OAK provides the needed air directly to support combustion and draft.

I have a very tight house, verified by blower door test, coming in at 0.8 ACH50, or perhaps 0.04 ACH "natural" (worst case weather). I also have an OAK on the small stove in the lower level. When lighting the stove, I've sometimes had to quickly open a window, then run upstairs to kill the dryer or range hood to kill the downdrafting, despite the presence of the OAK; both chimney and OAK draw air inward. I sometimes leave the stove door cracked open for a few minutes, even with no other devices running, to ensure filling the chimney with warmed air before closing the door and letting the OAK start drawing (I have a four-foot upside-down "U-tube" cold air trap in the OAK duct inside the wall; I don't really know how effective that is when the stove is not running).

In building a new house in a heating climate, it really does make sense to make it deliberately as tight as possible and very well insulated. This isn't rocket science; it's building science, and the techniques for getting it right, including ensuring that the shell is free of moisture accumulation problems (rot, mold), are well established by now. The old advice that came into being after the first Arab oil embargo back in 1973 encouraged making houses tighter, that "the house should be tight, but not too tight - the house has to breathe," simply does not work. This is well understood now. It just took a great many moldy houses to force designers to understand what was happening and come up with good solutions.

 

[Oldman47]

DickRussell, I am building a very tight building. So far I have spared no effort to make it as air tight as I can. When I specified a heat recovery vent system the HVAC guy looked at me like I had lost my mind but it is in the specs. I also have routed an OAK but so far have not penetrated the outside wall for it, it is just an open ended pipe in the basement that ties onto where my stove goes. The stove is yet to be placed because I need to finish installing the hearth the way my wife wants it to look. That means that today the OAK is just a piped up floor penetration into the basement. Tight is tight but I have no idea how successful I have been. When that first load gets lit, I will have an idea of the need to take that OAK through my outer wall. Until then I am going to make believe that my house breathes well enough that I can just burn cold basement air. If I need to go through the wall it will be very simple with the insulated vent pipe already run in across the top of my HVAC supply ducting. What a pain that run was.