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Preventing Puff-Backs: Time to Call the Chimney Sweep

Prevent Puff Backs, call the Chimney Sweep Most Vermonters are not thinking about their wood stoves during the dog days of summer. Instead we are trying to keep the beer cold and find the least populated swimming hole. But wood stove season is not too far away. If you have ever experienced a puff back, you know it’s time to contact the chimney sweep.

Puff-backs are usually associated with oil furnaces, but wood stoves are also susceptible. Puff backs, or back-puffing, occurs when gasses are trapped in the firebox of the stove. If the puff back is bad enough, it will send soot and creosote into your home, in very rare cases, a puff back can break the glass front of a wood stove.

Wood stove puff backs have many causes ranging from huge problems like fundamental structural complications in the stove, chimney and pipes to easily solved troubles like insufficient air supply in the house. Let’s start with most obvious and inexpensive solutions first. This is where Dick VanDyke, or your local chimney sweep, comes into service:

  • Blocked passages in the stove– Over time creosote, ash and fly ash can build up in your stove and chimney and prevent the free flow of smoke. Birds nests, dead leaves and other contaminants can block the chimney from above.
  • Pipe layout — Too many bends and turns can cause problems. Your pipes should be as straight and vertical as possible.
  • Leaky chimney or pipe system — Leaks in the chimney or pipe act like leaks in a sprinkler hose or a vacuum cleaner hose; the draft will pull air through the path of least resistance — which may not be where you want it to be if there are leaks. Test for sizable leaks with a small hot fire, with the stove’s inner damper open; go around the pipe joints with a stick of incense, and look for spots where the force of the draft pulls the smoke in.

The more difficult-to-solve puff back problems can be caused by:

  • An over-cool chimney or pipe system — because smoke is lighter than air, it rises. Long, straight  runs of pipe can cool the smoke and cause it to slow egress from your home.
  • An over-sized flue — Hot gasses lose their heat and momentum in large spaces. This problem is common to stoves vented through a fireplace chimney.
  • Outside Chimneys — Outside chimneys are more difficult to warm up and lose their heat faster that enclosed pipe systems, making it difficult to to warm the flue enough to make it draw well.

The best remediation for the smoke damage and soot caused by puff-backs is prevention. But if your summer duties preclude the care of your wood stove, Puro Clean Vermont is here to help. We are fire damage specialists.

image credit: chestnuthilllocal.com