I have a 20 year old Kent Tile Fire which I love, but it is the standard model and not set up to draw outside air. As a result, it warms one part of the house, but cools the rest (relatively old, leaky house). Question: is there a simple way to allow it to use outside air? Alternatively, since the Kent outside air version doesn't seem to be available anymore, what would be the best substitute having similar design and virtues, but able to take in outside air?
need some advice
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Todd
Minister of Fire
If you can't hook outside air directly to the stove this may help some.
www.condar.com/asv.html
If you install one close to the stove and low to the floor it may use that air for combustion. It also has a valve on it to shut off the outside air when the stove isn't in use.
Working on those leaks will help also.
www.condar.com/asv.html
If you install one close to the stove and low to the floor it may use that air for combustion. It also has a valve on it to shut off the outside air when the stove isn't in use.
Working on those leaks will help also.
Thanks for the replies. I am puzzled, however, by the piece on outside air recommended by Sawdustburners. I read it, but it seems to me that a wood stove running at high heat (50,000 Btu/hr) will require, by my calculation, a minimum of 250 cfm of make-up air to supply the necessary oxygen. For a 2000 sq ft house, that means a complete change of air in a little over an hour. If we try to supply that air from just the leaks in the house, it will certainly cool the house away from the wood stove, right?
thechimneysweep
Minister of Fire
You can read about the possible benefits of outside combustion air on our website at http://www.chimneysweeponline.com/hooa.htm.
If you decide to replace your Tile Fire with a model that allows direct connection to outside air, you might consider the five Pacific Energy Super Series models at http://www.chimneysweeponline.com/pacific.htm. As a former Tile Fire owner myself, I know you are going to be hard to please with any other model. The Super Series models are an uptake on the Tile Fire design, offering the same general appearance (without the tiles), same overall dimensions, same size firebox, same front-to-rear burn, same close clearances and same stay-clear view of the fire, but with an improved, cleaner-burning all-stainless baffle system, better overall efficiency and a lifetime warranty. As a bonus, any of the Super Series models will stand right where your Tile Fire stands, without any modification to the hearth or venting system.
When it came time to replace my Tile Fire I chose a Pacific Spectrum, and still couldn't be more pleased with it, 15 years later!
If you decide to replace your Tile Fire with a model that allows direct connection to outside air, you might consider the five Pacific Energy Super Series models at http://www.chimneysweeponline.com/pacific.htm. As a former Tile Fire owner myself, I know you are going to be hard to please with any other model. The Super Series models are an uptake on the Tile Fire design, offering the same general appearance (without the tiles), same overall dimensions, same size firebox, same front-to-rear burn, same close clearances and same stay-clear view of the fire, but with an improved, cleaner-burning all-stainless baffle system, better overall efficiency and a lifetime warranty. As a bonus, any of the Super Series models will stand right where your Tile Fire stands, without any modification to the hearth or venting system.
When it came time to replace my Tile Fire I chose a Pacific Spectrum, and still couldn't be more pleased with it, 15 years later!
thechimneysweep
Minister of Fire
To my knowledge, nobody does that. Our installers certainly don't, and due to our local code authorities' interpretation of Washington State Law, we've been required to provide outside air for every woodstove we have installed for several years now.
The scenario you refer to is illustrated by a rough sketch on woodheat.org's website that depicts a situation where the wind is blowing downward on the chimney top with sufficient velocity to simultaneously cause a chimney backdraft AND create enough negative pressure behind the house to cause burning material in the stove to be vacuumed backwards through an outside air intake located on the leeward side of the house and set fire to surrounding combustibles.
While this scenario might appear to the casual observer that it may, in theory, be possible, nobody, including the owner of that website, has ever produced any actual evidence that it has ever happened. Despite several challenges to do so on our website, on this forum, and in several E-mails to the man who published the sketch.
IMHO, anybody foolish enough to build a house in an area victimized by winds strong enough to create that scenario should invest in some ruby slippers, to facilitate the post-windstorm return of his house from Oz.
thechimneysweep
Minister of Fire
Not quite. Even the guy who published that sketch isn't crazy enough to suggest that wind-induced leeward depressurization could ever develop enough force to overcome chimney updraft. On his own website, he describes a study he participated in that showed it required a combination of the weak updraft created by a dying fire AND a room depressurization on a magnitude of 10 Pascals to reverse the chimney outflow. He also states that a typical chimney in use develops an updraft of up to 50 Pascals. Mom nature isn't likely going to create -60P depressurization on the backside of your house in any windstorm you're ever going to live through. Have another look at the arrows in his sketch: in order for this idea to appear even remotely plausable, an extreme combined push-pull effect of downdrafting and leeward depressurization would be necessary.
And, in the absence of any confirming evidence whatsoever, remotely plausible is about the best this theory can hope for.
And, in the absence of any confirming evidence whatsoever, remotely plausible is about the best this theory can hope for.
I think it's important to keep in mind the magnitude of the pressure differentials we're talking about here. The woodheat.org article includes such numbers as -10Pa, -15Pa, and -30Pa. A "Pa" is one Pascal, a commonly used unit of measure of pressure (or pressure differential in this case) in the SI system. A Pa is a very small unit of pressure: 1 mmH2O = 9.80665 Pa. So, a 30Pa pressure differential across a structure, or from inside to out, or through an appliance, is the equivalent of 3.06 mmH2O, which really ain't much. Yes, it will (as will any pressure differential) encourage air movement...but darn near any other influence could overcome that small pressure differential. It would be overwhelmed by an oven range hood or a dryer, or a bathroom ceiling vent fan...or, I think, by the draft of a well-installed and burning stove. Rick
thechimneysweep
Minister of Fire
Depends on the design of the stove. My Pacific Spectum gets its secondary air supply from the same plenum as the primary air. Introduce outside air into the plenum, and that's what feeds both fires. Other models we've sold have pulled secondary combustion air from the room, regardless of whether or not the primary combustion air came from outside.
thechimneysweep
Minister of Fire
Rather than edit it out, I'd like to nominate the phrase "regardless of whether or not" to the awkward writing hall of fame.
thechimneysweep said:
Actually, Tom, I don't see anything wrong with that phrase. Now, if you had said, "irregardless of whether or not", that might be a different story. I'm of a mind that use of the word "whether" pretty much demands the "or not". Rick
thechimneysweep
Minister of Fire
myzamboni
Minister of Fire
sawdustburners said:
Start here, sawdust...if you can get all the way through it, submit a synopsis to me. :lol: Rick
http://www.fpl.fs.fed.us/documnts/fplr/fplr2136.pdf
stoveguy2esw
Minister of Fire
thats enough to hold a serious pyro's attention for a few days anyway. i got through 4 pages before i thought... "wait a minute i dont need to know this much detail" and clicked out.fossil said:
stoveguy2esw
Minister of Fire
i hear ya rick, gawd, but burning a stick is so complicated. i say "load wood, remove ash, repeat."fossil said:
as for the CO released by a woodstove , i would bet that a mid 1980's automobile releases more minute running for minute running. especially with a modern reburn stove , which burns away a large amount of CO in the secondary combustion function of the unit.
sawdustburners said:
Here's how I got the 250 cfm, it is based on the oxygen needed for combustion to supply a certain amount of heat, which I chose to be 50,000 Btu/hour for a wood stove burning at the higher part of its range.
The energy content of wood is about 6,400 Btu/lb for air dry wood, 20% moisture, according to this source: http://bioenergy.ornl.gov/papers/misc/energy_conv.html
That means we need 50,000 Btu/hour / 6,400 Btu/lb or about 7.81 lbs of wood per hour.
(note that the numbers following chemical symbols below are subscripts, they didn't come out right.)
To get the amount of oxygen needed, I assume wood is largely cellulose, a polymer with repeated units of (C6H10O5), so we need 6O2 to convert (burn) each unit completely to CO2 and H2O. The molecular weight of each unit of cellulose is (6x12 + 10 + 5x16) = 162 and the molecular weight of 6O2 is (6x16x2) = 192 , so for each pound of wood, we need 192/162 = 1.19 pounds of oxygen to burn it completely (and even more if the burn is not 100% efficient and some oxygen escapes up the chimney).
Air is 21% oxygen and 78% nitrogen with the last 1% some trace gases. Again, using molecular weights and ignoring the trace gases, the relative weights of air's components are 21%x16 = 3.36 for oxygen and 79%x14 = 11.06 for nitrogen, for a total of 14.42 in air. This means for every pound of oxygen, we need to supply 14.42 / 3.36 = 4.29 pounds of air. Now a pound of air at standard temperature and pressure (about 70 degrees F and 14.7 lb/sq. in.) is 387 cubic feet. See this source for example: http://www.newton.dep.anl.gov/askasci/gen99/gen99510.htm
Putting this all together, we need 7.81 x 1.19 x 4.29 x 387 = 15430 cubic feet / hour or 257 cfm.
Catching up on this thread I want to thank all contributers for a great discussion. And tip of the hat to SteveD for the great calculations that saved me from the head throb of finding the correct formulas and running the numbers. I'm going to OAK the PE T6 with a valve so that this winter I can start gathering some data on OAK vs non-OAK operation in this old farmhouse. Should be pretty interesting.
BeGreen, you're welcome and I believe your experiment should be very interesting.
"One good experiment is worth 1000 expert opinions" - anon.
"One good experiment is worth 1000 expert opinions" - anon.
I welcome suggestions for monitor points to establish baseline metrics for this experiment. I don't have a lab load of sophisticated equipment, but can do IR thermometer readings of door, window, recessed ceiling light penetrations to see if there is a temp difference. And I can do observations of airflow based on incense stick smoke. Any other suggestions for data points?
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