Chimney issue with high wind

[maxdog]

happy new years eve everyone.  It has been a while since I have been on the site, but i again turn to you for assistance!

I recently put in a wood pleaseant hearth wood stove several months ago in our cabin and have been using it without any issues until this past weekend.  The family and I were up for some sledding and fun( Snow Shoe, PA) .  I fired up the stove without issue and it was going all day, when a high wind storm came thru and the fire started to die, and soon I was getting smoke backed up thru the stove door and pipe connections.  You would hear the wind comming and then the smoke would bellow out in the cabin. 

I checked the chimney for blockage(nothing) No significant creosote either.  I started it again on sunday and it would burn until I closed the door and a gust of wind came and forced smoke  back into the cabin.   

Any thoughts??  My only thought is I need to get the chimey higher??

Thanks,


Karl

[PEG688]

Is there any type of cap on the top?

How far off the roof is it horizontally top of pipe to roof, measured level across cap to roof?

How far above the ridge line is it , if it close to the ridge? 

[flyingvan]

Higher is almost always the solution to a poor drafting chimney, but if a certain wind condition makes higher pressure aound the terminus (where the smoke comes out) and a lower pressure in the house, that's where smoke will go.  PEG688 asked the best question about a cap.  Those funny looking conquistador caps that turn with the wind are specifically designed to fix that very problem.  Can you post a picture of the layout and describe what direction the wind was coming from?

http://www.american-chimney.com/chimney-services/smoking-chimney/

     Every house with a fireplace has at least TWO chimneys---the one attached to the fireplace, and the house itself.  You have to give a good reason for the smoke to go up the one you don't live and breathe in.  The chimney must be the tallest thing.  The smoke should be kept hot so you don't get a cold air dam (this is why single wall pipes going right out the nearest wall have problems)  Sometimes modern houses are built too airtight with no attention paid to return air.  Air is pumped out through kitchen range hoods and bathroom fart fans, so that air gets replaced through the chimney.
     Another possibility is the wood you're burning isn't seasoned properly.  A neighbor called me over because his wood stove was spewing black smoke---he was burning pieces of railroad ties.  Ick.
     I looked up Pleasant Hearth wood stoves, and as near as I can tell there isn't an option for drafting outside air directly into the unit-- this solves any pressure differential problems and stops the fire from pulling cold air in around windows and doors, but the units that do pull outside air are supposed to corrode faster dues to moisture.  None of mine have had that issue yet, the oldest one installed in 2003, but it's fairly dry up here.
    Good Luck!

[maxdog]

Flyingvan, I have a picture but I can't seem to attach it the post???? 

[maxdog]

Peg688, I have a cap on it and it is about 10' from cap to roof on the horizontall, but significatlly lower then the ridge.  I have a picture I'll post when I figure it out.   I was going off the dirctions from sealkirk, but after this epesode, I feel that it needs to be above the ridge. 

[PEG688]

Sounds like your at close to minimum standards.

Code requires that a chimney be three feet above the roof where it exits and two feet higher than any part of the roof within ten feet.

http://inspectapedia.com/chimneys/Chimney_Height.htm



To post a photo the photo needs to be at a host site like Photobucket, or some thing like P/B

If it's a triple wall type pipe , go up one more section , at least a 2 foot one , if you can get the type you have in 2 foot sections.

G/L
PEG

[flyingvan]

Smoke always goes up the tallest chimney....Imagine a metal box with two pipes coming out of it, that turn and go straight up---the same, except one is taller that the other.  If you light a fire in that box, it'll pull air in the lower pipe, and exhaust smoke out the taller one.  If your chimney is lower than your ridge, it would explain the problem...

   If you can post a picture somewhere else (like Facebook)  just do that, right click the picture, click on properties, highlight the address (the part that starts http) and copy it.  When you come back here click the photo icon up on the toolbar (looks like a little mona lisa) then paste that address between the brackets that show up

[Don_P]

I would certainly try raising the stack after checking the makeup air by opening a window. But, it also sounds like you are in the mountains. I'm about 600' below the ridge behind the house. Occasionally we'll get a wind from just the right direction that creates a very strong roller down the slope and we'll get a backblast. My setup in the barn is very rustic and it has in the past blown flames out the intakes a time or two. Too exciting in a room full of sawdust, I've got an elbow up top as a cap shielding it from that direction now. The storm before Christmas roared over us with 60 mph winds for about 24 hours, the wind came across in the normal prevailing direction and all it did was suck down the firewood from a too good draft. Which is a longwinded way of saying topography can be another important factor. Go outside in heavy winds and notice where they are blowing from and how the stove is performing, when it is puffing check again. For us its a noreaster, what I call our back wind, that causes trouble sometimes.

[JRR]

I seen many chimneys that have been "raised" by merely adding a few feet of liner-pipe up from the existing.  Don't know how effective it may be.

[Redoverfarm]

The 10' rule on a horizontal plain from the chimney top is a little deceiving.  I went with this and I was still unable to have the stove to draw correctly.  Unlike some it was not a quick fix by adding a few extra feet of pipe.  Another problem that existed with mine was that the flue was on a shed roof on the inside of a 90 degree roof lines of two roofs which had 10/12 pitch.






I have a mason flue and eventually added approximately 7' to the existing.  It did help 100% of the draw on the stove but did not cure it completely as it pertained to backdrafts.  Occassionally when the wind and barometric pressure is right it will still backdraft or force smoke out of the stove.  From various persons that I have talked to that burn wood have come to the conclusion that this is normal even in the best constructed flues.  For mine I have cleared the ridge on the one roof but lack about 2' on the other which is some 30 feet from the flue top.  For safety reasons I decided not to raise the flue the additional 4-5 feet.

There are several factors that could be contibuting as well to the stove not drawing.  The flue heigth being a major factor but the lack of air intake in the stove could be another as well as the type of stove.  A faulty door gasket could also be a factor. 

So basicly my stove works correctly 98% of the time but there is still that 2% when conditionsl are right ( Or Wrong for me) that it will backdraft or blow smoke.  So I would start with the flue extension and work from there on other things that might be contributing. 

[flyingvan]

I posted this elsewhere but it's a very good article (with pictures!) http://www.woodheat.org/best-practices.html  It's probably too late to put some of this into practice but I know people read these threads that haven't broken ground yet.  If, during the design phase, you put your fire near the center of the structure (not an outside wall), have the chimney exit the highest part of the roof, have the chimney go as straight up as possible, and draft outside air---you shouldn't have problems.  Actually there IS one exception----if it's very cold outside you can get a 'cold air dam' in the chimney.  We just wad up a newspaper loosely and shove it up the flue and light it just prior to lighting the kindling and no smoke whatsoever gets in the house.

[Redoverfarm]

I posted this elsewhere but it's a very good article (with pictures!) http://www.woodheat.org/best-practices.html  It's probably too late to put some of this into practice but I know people read these threads that haven't broken ground yet.  If, during the design phase, you put your fire near the center of the structure (not an outside wall), have the chimney exit the highest part of the roof, have the chimney go as straight up as possible, and draft outside air---you shouldn't have problems.  Actually there IS one exception----if it's very cold outside you can get a 'cold air dam' in the chimney.  We just wad up a newspaper loosely and shove it up the flue and light it just prior to lighting the kindling and no smoke whatsoever gets in the house.

I agree completely.  But for  me and many others it seems we are always playing "monday morning quarterback".  Hopefully someone just beginning their build will pick up on the this thread. 

[Kat]

I'm not an expert, but if all else fails this might help.

http://www.woodlanddirect.com/Chimney/Wind-Resistant-Chimney-Caps

My mom's place is back against a hill and we get lots of wind. She was having the same problem no matter what we did with the chimney. This cap solved her issue.

The last house we lived in had a small single story that was added on to an old 1 1/2 story house. The stove was located in the add on. When the winds were from a certain direction, they'd swirl against the roof the old part of the house and go back down the chimney. There was no way to lengthen the chimney enough to get above the tall roof of the old house. My husband attached a sort of shield on the side of the chimney cap that the problem winds came from. It somehow did the job. Although if you try that, you might want to attach it with something more permanent that vise grips. 

[Dave Sparks]

 Really good info in this thread. An anecdotal test of draft can be done by a test how well a chimney draws ash dust out of a cold woodstove. By opening and closing the damper, you should see the dust from removing a scoop of ash with the door open drawn up the chimney.

At least the test will keep your dusting person happy

[maxdog]

Thanks to everyone with all their great info!!  I am going to add enough pipe sections to get over the ridge line!  H as anyone used a barometric damper on their wood stove??  a bunch of guys at work has suggested this. 

Thanks,

Karl

[flyingvan]

  Barometric dampers are used more to maintain an optimal air mixture for the most efficient burn of wood.  They are a very worthwhile addition, but not a fix.  In fact, if there's a drafting problem, they can do more harm than good.  I'd recommend what you're already doing, (extending the chimney) add a directional chimney cap (we called them 'conquistadors' because they look like old Spanish helmets, don't know the real name) then when that's all working well, you can add the barometric damper later.  They save you from adjusting the airflow all the time...For me, though, it's like always buying the car with the manual transmission---I'll trade a little convenience for simplicity any day.
  To tack on to what D. SParks said, another good test is, get a fire going good.  Turn on your range hood and bathroom vent fan.  Make sure all your windows are shut tight.  Now open your front door a crack, from the outside, and see how quickly a square of toilet paper sucks into the house through that crack.  It'll give you an idea how much return air you're lacking.  There are fixes---like running a 5" duct from outside to the return air of a central heating system so the return air gets conditioned and filtered before distribution, or since most cabins lack a central system, run it behind and below your wood stove.  (Many wood stoves have a place you can directly attach it to the burner box)  But from what you describe, I'd bet a $50 hardware store gift card that raising your chimney and installing a good cap drastically improves your draft

[Pine Cone]

You might also look into chimney caps that move in the wind like a windvale.  You see these all over in windy cities like Wellington New Zealand.  Seemed to work in the house I stayed in that had one.

Here is an example of one, probably from the Seattle WA area
http://www.luxurymetals.com/wind_directional_caps.html

I'm sure there are other sources...