Wood Stove questions

[Kirk_Allen]

I put in an old wood stove in the shop and have some challenges.

The challenge I am having is that when the wood burns down, the wind seems to push all the smoke back down the pipe and into my garage.

I have 4 feet of vertical pipe above the stove that goes into a 90 degree elbow. Then it goes 2 feet to the back wall then 90 degree turn up on the outside.  From that last bend, the pipe goes up 10 feet and the top is just above the peak of my roof.  It has a standard vent cap on top.

Any suggestions on how to prevent the back draft problems.  
The flew is located 4 feet above the stove.  When the fire is good and hot all is fine.  Its when I get down to coals that I am having the problem.  Went out this morning and the garage was filled with smoke.  Outside winds were around 20 mph.  Once I restoked the stove all was fine..............other than I have to take another shower because I smell like smoke from getting it stoked again.

Any input is appreciated.  

[Murf]

I'm guessing it's a combination of two problems.

First, the top of the pipe should be a minimum of 2' higher than the ridge of the shop to ensure a good draft.

Secondly, the pipe outside is probably uninsulated pipe, which means it is basically a big radiator. When there is little fire or heat in the stove the smoke is cold by the time it gets to the top it, at that point the only reason for it to go up is the smoke behind pushing it up.

You could probably reduce, if not eliminate, your problem by putting one of those swivelling tops on the pipe, the kind with a sideways outlet and a little weather vane thingy on top.

This would ensure that the opening always as much suction from any breeze blowing as possible and help make as much draw on the stove as possible.

[Kirk_Allen]

The top is 1 foot above the peak now.  I have another section I can add to see what that does.  

The pipe is un-insulated so I could see the heat loss issue.  I had hope that going from 7" pipe to 6" pipe would have lestened this issue but maybe not.  I will have to check the outside pipe to see how hot it is getting up high.

Not familiar with the swiveling tops.  I will try to find one and try that .

Thanks
Kirk

[etat]

http://www.chimneys.com/burnsec/chapter6.html

[MULE_MAN]

Thanks cktate

                Some pretty interesting info. on that site   8)

[Grawulf]

Kirk,
I've had really good luck with an H cap when I haven't been able to get enough heighth to get above the ridge. It's three pieces of stove pipe  assembled just like an H looks and your main chimney attaches to the bottom of the center of the H. If the wind blows down the chimney, it blows out of the bottom of the two verticals on the H and doesn't blow down the main chimney. Used to be used on industrial buildings that had mainly flat roofs. Works well but creasote tends to drip from the bottom of both sides so if you have white siding...... :-/

[Kirk_Allen]

Thanks for the web link Charles.  Some great info.  I added 2 feet to the hight of the stove pipe. I will find out how that works out tonight when the fire burns down.

I know the top of the stack is getting enough heat.  IT WAS HOT.

Added the two foot section and now it seems to be working pretty good, but then again I have hickory buring in the stove.

Grawuff, the H cap sounds pretty good.  I will try that next if this doesnt fix it.  

Three peices of stove pipe?   I assume that would be three T pipes?

[UNCLEBUCK]

Here is my pile of junk woodstove in my little woodshop . I have the same set up for pipe it sounds like except I put the throttle past the first 90 elbow and then it goes out 3 feet with a slight slope upwards then 90 elbow then up 8 feet to just clearing the shingles on the roof on the north side of woodshop . uninsulated and I just wanted to show that I never have had any problem like you got . Maybe its the pipe that goes horizontal through your wall , maybe if it had just a slight slope upwards that the smoke would roll up and out . I dont know anything about this kind of stuff but I burn alot and I did stay at a holiday inn last night ! goodluck ,nothing better to get a headache from than stinky smoke .  :P                                                                          

[UNCLEBUCK]

I asked my dad and right away he said like the rest that a directional cap might take care of it ok . hope you get fixed up !

[Grawulf]

Kirk,
It'd be a T section and two straight pipes on either end of the T
                            

[gizmo]

Another thing is to make sure you have enough make up air or you will get negative pressure in the  bldg. Crack a door or window a tad and see what happens whenits downdrafting.

[Kirk_Allen]

Kirk,
It'd be a T section and two straight pipes on either end of the T
                            

I looked at the T section this afternoon and not sure I understand how your building this.  Now Im not stupid but I didnt see any way to make the H with three parts.

The Bottom of the T would hook to the vertical exhaust.  Then you have a left side and a right side to finish.  Not sure how your getting the H without an adapter.

[Grawulf]

Kirk,
Sorry about not making myself clear - you could do it with three Ts - it would just cost a little more. I usually cut a hole in the center of the vertical pipes, cut the T ends to fit the verticals, and screw the pieces together with angle brackets. It does take time to do all the cuttin and fittin, so your three Ts would be less time consummin'

[Grawulf]

Unclebuck,
I noticed from your picture that the pipe going into your chimney thimble is silver - stainless or galvanized? If it's galvanized, you should probably change it over to the regular black stove pipe. when galvanized is heated, it produces a toxic   gas - maybe that's why your wakin' up with headaches?

[Mark M]

Kirk

Make sure to watch that thing for creosote buildup. Single wall pipe runs cooler and will cause the creosote to condense in the pipe.

[Paschale]

Hey Grawulf...I like your picture!   8)  I know it has nothin' to do with woodstoves, but that's cool seeing the edge of the lumber up close, and in focus, and you way down at the other end.  Cool beans!   ;)

[Grawulf]

That's me!!!!!!! Usually a little fuzzy around the edges  :D - Thanks Paschale

[Kirk_Allen]

Looks like the problem is solved................I hope.

I added two feet to the top of the pipe so now it is 3 feet above the peak of the garage.

Charlie, thanks for the web link.  Great info.

I warm the flew with one peice of newspaper then start the fire.  No smoke comes in the garge. Pre heating the flew made a big difference.  

The last two fires have burned down with no backdraft of smoke but tonight will be the test.  We have 30 mph winds.  The fire is rocking right now.  Had to quite working out in the garage it was so hot.  

Once it burns down we will see if the extra hight above the peak solved the problem.

Thanks for all the input.

[Kirk_Allen]

All fixed 8)

Woke up this morning to a cool garage but NO SMOKE!  Winds were wicked here last night but the stove worked great.  Had enough coles after 10 hours of burning to start another fire this morning.

Thanks again for all the input.

[etat]

Thanks for updating us.  I'm glad you got it fixed.

[Phorester]

Good for y'all in solving this problem. Coming in late to this discussion, but I have a cousin who had the same problem a few years ago.  He got his pipe  2' above the roof ridge, it worked like Kirk's did. Can't fight mother nature and physics!

[SwampDonkey]

Kirk

Could you also move the stove closer to the wall and put some heat shielding behind the stove, like a sheet of metal on the wall? Them elbows are places for creasote to built-up. Move closer and elimate them elbows. Inspect that outside section annually for corrosion, its safer to have a selkirk flu up there for that 3 feet outside. ;) Make sure ya clean them pipes every month.