# how to reverse a wicked backdraft in the morning



## nyny (Nov 11, 2014)

never happened before.  very windy today. opened up the door and ashes and smoke billowed out.   draft is always fine, chimney meets or exceeds all clearances.  tried cracking a door and got worse, children are hiding under their beds and covering their ears from the screaming.    can't reverse it, wondering what to do if there was a decent fire in there and all this happened.


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## spirilis (Nov 11, 2014)

Open a door much wider, open stove, point a heat source (heat gun, propane torch, heck even try a simple lighter) up the flue?  Then once you get any indication it's starting to reverse, light some newspaper and close the stove door?


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## pen (Nov 11, 2014)

With a decent fire, it would be rare for that to happen in a proper system.  

Is this a wood stove or a fireplace?  I don't see it in your signature so I don't know what you are working with.

How tall is the chimney?  What kind of chimney?  What's the diameter of the chimney liner?

I'll get a downdraft in my basement wood stove from time to time, and to get things going in the right direction, I put the hose on the outlet of the shop vac, turning it into a blower, and put the hose into the air intake on the back of the stove (you may or may not have this depending on the stove you are working with, if it's an insert or not, etc) and let it run for a minute or two, essentially pressuring the stove stove and getting the air moving up the chimney before I start a fire.


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## DougA (Nov 11, 2014)

I would assume that it's a very windy day and the wind is coming from a particular direction that is affected by your chimney location and roof design or even buildings close by.

You need to open a door or windows that will relieve the pressure on the downdraft because air will flow out of the house via the easiest route. You'll have to experiment to find which side of the house needs to have doors/windows opened.  Some may make it worse.  Side matters, opening all of them my not change anything.

It would seem that you house is terribly drafty.  Air will only flow in your chimney of there is more pressure outside the house than inside  To have less pressure inside, you must have a lot of leaks that allow air to infiltrate out, creating a vacuum inside. As I posted once before 'air sucks, it doesn't blow' The ultimate job is to fix the leaky house.

If you can't get a proper draft after all of that (and using very dry kindling), use another heat source for the day or until it is safe.


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## blades (Nov 11, 2014)

AS no one asked what kind of termination on the flue out side. If is just a top plate with a screen that is part of problem. Ther ones tha are side shield that prevent wind shear problems like you are experiencing.


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## Jags (Nov 11, 2014)

At first I had a rare but occasional downdraft (wind dependent).  My fix was to add two feet to the stack height and change the cap.  I used a cap, much like this: Those two items virtually eliminated down draft. (for me)

http://www.menards.com/main/heating...nt-6-s-s-deluxe-rain-cap/p-1323294-c-6894.htm


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## nyny (Nov 11, 2014)

spirilis said:


> Open a door much wider, open stove, point a heat source (heat gun, propane torch, heck even try a simple lighter) up the flue?  Then once you get any indication it's starting to reverse, light some newspaper and close the stove door?




i couldn't reverse that draft with a flame thrower. tried everything.  same setup for 5 years.


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## Sconnie Burner (Nov 11, 2014)

Is there a bathroom vent fan running or a clothes dryer that is being used? Those will case a vaccum effect and your chimney will become the inlet.


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## Ford850 (Nov 11, 2014)

As others have said, your downwind side of the home is losing air.  Close the dampers on the stove, open a window on the upwind side for several minutes, and then try to use a torch or blower up the flue.
Do you have a cold air supply? They can cause this too if on the downwind side of your home.


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## begreen (Nov 11, 2014)

Either the chimney is actually drafting poorly, poorly located, or the house has near negative or negative pressure in it. If the house is tight then a bathroom or kitchen fan or clothes dryer can do this. Less obvious sources would be a strong air leak upstairs like an attic vent, attic door, leaky or open windows. 

Is there a stainless liner in the chimney that is sized to the stove? How tall is it?

Also, tell us about local conditions. Was it very windy this morning? What kind of cap is on the chimney?


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