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Chimney "Diffuser" For Outdoor Wood Burning Stoves
“Outside wood boilers use a lot more wood when the wind is blowing. I found a low-cost way to solve that problem,” says Ed Maas, Eden Valley, Minn.
  His patent pending “Top Hat” chimney air diffuser is designed to minimize the wind’s ability to siphon heat out. It consists of a stainless steel cylinder with metal support fins inside, which fits over the top of the chimney flue. An optional lever kit can be used to adjust the cylinder up or down.
  “When strong winds blow, wood consumption is at or more than 50 percent higher than on calm days,” explains Maas. “The fast moving air not only sucks the heat out with it, it also forces a very rapid burn time of wood. If you adjust the damper to control the air flowing through it, the fire will starve for oxygen and throttle back the amount of heat produced.”
  His diffuser knocks down the wind velocity at the top of the chimney by introducing outside air at the top of the flue. “When the diffuser is raised, up to 75 percent of the air caught in the wind’s siphoning effect is outside air. That means far less heat is pulled out the chimney. Down-drafts from strong gusts are also reduced,” says Maas.
  The optional adjustment lever makes it easy to raise and lower the unit. “When fully lowered, the top of the diffuser is located just below the top of the flue pipe. That position is for calm days and permits normal draft,” says Maas.
  “When the diffuser is up at its maximum height it’s about 15 in. higher than the stove’s chimney. The diffuser’s opening is about 3 times larger than the chimney, so the chimney is forced to draw most of its air from around the cylinder.”
  Maas plans to market the Top Hat diffuser and expects it to retail for about $250.
  Contact: FARM SHOW Followup, Ed Maas, 56520 365th St., Eden Valley, Minn. 55329 (ph 952 486-8821; cell 320 493-2330; edw.maas@gmail.com. A new website is coming but updates will be posted at www.therock-star.com).

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2013 - Volume #37, Issue #6