Fireplaces, Heating Stoves, Flues and Chimneys - need some woodstove help

I have a cabin with a woodstove and this weekend I used it twice. The first night was fine but the 2nd, the smoke was terrible. I dont have much experience but I had the doors open and the flue wide open. I have 4 questions:
1. Theres a metal plate in the back the starts at the bottom rear and extends to the top front away from the stovepipe. Should I remove it and what is it for?
2. Is it ok to have the dors open?
3. Should I put a flue in the stovepipe?
4. Should I take the rack out and put firebrick in it?

First did you have the chimney cleaned prior to the seasonal use? While it was burning did you see smoke from the top of the chimney? Take some pix of this plate you see and post it on a site such as photobucket.com and copy/paste the HTML code to your reply post. That way we can see what you see. Do you have a metal chimney or a brick one? By rack, I am assuming you are talking of the wood rack. No, leave it in to allow air under your wood.

No I didnt clean the chimney as Ive only used it like 4 times. Its in my cabin 5 hours away so I cant get a pic. I used stovepipe for the chimney up towards the top of the roof then 90 it outside then another 90 with a cap. Used a clay pipe going through the wall.

Bingo, I found your problem. Not sure about the codes where you are, but you can't have more than 2 45's. You are creating a back up with too sharp a bend, twice in the same run.

Chandler - are you sure?

I thought it was 2- 90's not 2 - 45's. My stove has a 90 where it comes out of the back of the stove and another one where it turns to enter the thimble/chimney. Mine draws just fine.

After thinking on this, it is a "stove", not an in-wall fireplace with insulated pipe, so you are right, two 90's. We just got through re-routing back-to-back fireplaces where they had 3 45's each forming double flues, wrapping around each other. It looked like a spider web. Can't figure why the framers didn't make considerations when they built the chase. But with stoves, yes, two 90's. Even my plenum stove in the basement has the two 90's.
Cleaning the flues is important, and is very difficult without taking one of the 90's apart to get it all out.
Thanks, Mark, for the heads up.

Still doesnt answer why the plate is in there. Also, what do I use for the ceiling around the stovepipe?

The plate sounds to me like it is the baffle you are talking about. I assume this is an older stove?? Before cats where installed in stoves, they used a steel baffle or plate that slowed down the gasses and aided in the combustion of the gasses coming off the wood. They have to travel around the plate to go up the flue.


Concerning your #2, it should be fine to leave the doors open if you wish for ambiance, but your stove pipe needs to be big enough to flow that much air, which should be fine if smoke doesn't roll out when they are wide open. If you do this though, you need to be aware of sparks flying out.

#3, I assume you mean to say damper??? in your stove pipe??? If you don't have one now, I would not worry about it.

In re-reading your question I see your original problem and forgot to mention this, does your flue rise above your roof line? It is very possible that between the first and second nights the winds and/or pressure changed and this caused the flue to not draft properly. Perhaps even the fire was hotter the first night (fire in the stove I mean), this would create a better draft with the doors open as there is alot more air coming in.

Ok, so will it hurt anything or cause excessive smoke to take the plate out? It reLLY takes up room and pushes the smoke out the front door.

I don't think it will hurt anything. I would hate to see you have to cut it out, as if it is welded it, or something like that. If if bolts in and you have problems, you can simply put it back in. Its your call.

check that stove pipe height too. Make sure you are above the roof, at least 2-3 feet I would say. Assuming you don't have any trees to close or other house appendages.

I know its not above the roof. Should I extend it? What effect would this have? I thought it would be worse cause wind could get to it easier.

Raising the chimney/pipe helps to prevent down drafts that would make it harder for your stove to draw.

Agree. With the cap below roof level, the tendency will be for the prevailing wind to cause a downdraft, or ''still" air. If you can get the wind to blow across the top of it, it will actually create a little suction and the draft will work properly.

Ok, Ill extend it next time I go up there.

I should have mentioned the reason for being above the roof. You want wind moving across the cap. It creates a low pressure area that causes air to 'want to' draft up your stove pipe. Sometimes you will have a back draft when it isn't fired up. This is what the damper is for, close it when the stove is not in use to minimize this. Otherwise, you will have the smell of ashes in your cabin from time to time. No harm done though.

For everyones benefit, sometimes the ridge line of the roof can be higher than the cap, IF the ridge is far enough away where the wind has enough distance to swoop down over the roof. It can be tricky sometimes. Bottom line is, it almost never hurts to go higher.

Man I have learned a ton on woodstoves the past couple days! Its ok to have 2 90's in it right?

Old chimney builder here. Any fireplace/wood stove/et, the chimney needs to be min 2' above any object 10' in radius. This is the basic code. Now as all codes go, if there another roof peak higher close to the chimney ( past 10' ) then it needs to be higher or trees creating down draft on windy days.

In CFMS on round duct work a 90 is equivalent to a 10' section of straight pipe in resistance of CFMS of flow.

Do you have the "Make of the wood stove and size which would clear up this "plate" thing...???

Where it goes though the wood wall there should me a Thimble/crock for that transformation. If its just a crock then specs are 8 " of masonry work past crock with a 1" air space.

They way thats solved is using for instance a "Hart and Cooley" metal vent all fossil fuel thimble.

There is no real limit in theory to how many 90s there are. Its all about draft, 20 90s can be supported if the chimney was a 100 '


The basic test to check all chimneys draft is very simple. After chimney is up get a book match light it and see if it can suck the match out. Theres the infield test. If the match just quivers then its weak..

Let me give you and example of how draft changes just in chimney height/extension. At 18 years old I built a 36" standard fireplace in a basement for a city firemen no doubt. After a year of burning he complained that when he set the damper at one notch he was to much draft and the next notch closed the damper.To change those settings I added 2' feet onto the chimney and it tweaked the damper settings

Thanx 21boat that helps a lot. It seems like I need to add about 4 feet.I did use a crock through the wall just need to put a ceiling in cause it has a tin roof with a vent cap to prevent sweating and obviously all the heat escapse through the ceiling. So the question is, what do I put aroung the stovepipe for the ceiling? Cement board or is the a prtective barrier I can use to prevent burning the osb?

[QUOTE=panteramatt;1566353]



I did use a crock through the wall just need to put a ceiling in cause it has a tin roof with a vent cap to prevent sweating and obviously all the heat escapse through the /QUOTE]


The 2 foot above in radius is for objects by the chimney. The chimney must be 3' above its roof penetration

Hold on here a minute. What gage stove pipe are you using?

The last I checked a clay crock needs 8" of masonry work around it and an 1' air space to be at code. Explains the SS thimble. An all fuel thimble needs to be used for any penetration through combustibles. On a side note a horizontal standard stove pipe needs to be 18 " from the ceiling except vertical.

This "sweating" of the pipe. A vent cap is not for stopping that and thats not the problem here. The sweating means the chimney is to cold period. It will build up dangerous creosote and rust the chimney out.


NASD: Wood Stove Installation and Operation (http://www.cdc.gov/nasd/docs/d001001-d001100/d001052/d001052.html)

NASD: Proper Installation, Operation and Maintenance of a Wood Stove (http://www.cdc.gov/nasd/docs/d000101-d000200/d000132/d000132.html)

Wood Burning Efficiency and Safety | Cleaner Burning Wood Stoves & Fireplaces | EPA (http://www.epa.gov/woodstoves/efficiently.html)

No,No, you read it wrong. The stovepipe never sweats. I said I have a TIN ROOF on my cabin with a vent on it to prevent sweating of THE ROOF and without a ceiling, it lets all the heat out through the ROOF VENT.