Smoke rolls out load door - any advice?

I do not have any kind or damper on the stove, barometric or manual. I did some mods over the weekend (and made a huge mess in the finished basement). I cut the rear half of the stove collar off flush with the "ceiling" of the stove (it was protruding 1-1/2" down into the firebox). I also installed a hinged smoke flap that reduces the load door height from 11" to 7". Another unrelated modification was the installation of secondary preheated air.

The mods were fairly productive. I think the hinged smoke flap did the most good. I doubt the stove collar did much, but I wanted to try it. I still get a slight amount of smoke curling out at the left edge of the door opening . I still need to attach a baffle slide to pull my baffle plate to the front of the stove and see if that helps. The preheated secondary is not quite functional, as I have to drill a 1" hole in the front of the stove, and I'm having a hard time allowing myself to do it unless it's absolutely necessary. I don't seem to be clogging up my chimney after burning coal for 2 months. The interior smoke pipe gets some buildup, but not much if I burn it hot.

I have not tried a candle test in my thimble. To reiterate my chimney setup, I have 18" of vertical 6" dia. double wall smoke pipe exiting the stove, then a 90 elbow, 12" horizontal to my thimble, a chimney tee, and then 12' of metalbestos pipe up the outside of the house.

When I lit the stove after all the mods, I was impressed with the draft when I warmed the flue with paper. Sure seemed like good draft to me. We get very little wind in the Big Horn basin of Wyoming, so I don't usually have any draft help or hindrance from wind.

I'll post some more on this when I get the baffle slide done. For now, I think I have the smoke issue improved, and can certainly live with what I have now even if it gets no better.

BTW - when I was doing the mods this weekend, I took the opportunity to dump the grates - I was surprised at how many rocks, clinkers, etc were plugging up the grates. After cleaning, I get much better air distribution through the grates, and a better coal bed. Looks like I'll have to inspect/clean the grates monthly or so.

I think I'm to the point where I'm ready to share the stove drawings/plans. I'll edit them to show the mods and get them posted.

Thanks again for the input.

Steinke

I would check the draft at the thimble. If the chimney stack has a good draft, your problem is most likely the stove design. "Stoves are not all created equal!" This is much more evident with wood burners, where you have more smoke to contend with.

Hey Wy, I had the same type of problem on a wood stove when I changed my exhaust pipe from 8" down to 6". My solution, simple; I created I small hand held inset that covered the top part of the door opening. This kept the smoke from pouring out the top, and still alowwed me to tend to the fire. Once the fire perked up, I could remove the insert and add new wood! If you use a wooden insert, cover the face with HD tin foil, and don't walk away when using! Good luck!

ideally you would have an 8" chimney, obviously because of cost, you want to avoid that, but sooner or later, thats where you'll end up if you don't want to keep playing around. i burn very sooty coal and have a top- loading stove, and absolutely no smoke out the top, with a farily tall 8" ID masonry chimney. in summation, your chimney is too short, small or a combination of both. i don't know what your exact setup looks like however, you could build a masonry/tile chimney in a weekend for a few hundred dollars.

Berlin - I think you are right. I'm going to stall, but in the end, I think 8" is the best solution. My efforts with the smoke flap seem to have produced significant enough improvements that I'm going to stick with this setup for awhile. I would however, urge anyone burning bituminous to begin with 8" chimney if they have the choice. I may look into a masonry chimney.

I also bought a used Warm Morning top load stove at an auction recently. It's going in my garage. I aquired 16' of 8" triple-wall chimney (no insulation pack, just triple-wall) from a guy for free. The DuraChimney triple-wall is rated for 1700 instead of 2100 degrees, which doesn't meet current code, so I'm not putting it in the house (plus no tee's are available for this old style class A pipe), but I'm anxious to see how it performs in the garage with the Warm Morning.

Thanks,

Steinke

Let me know what you might need for your triple wall piping. My cousin has a bunch (part of a 4 car garage full) of NOS pipe and accessories. It's a "matter of luck" finding something.

I think I have what I need for the triple wall install in the garage. If I had an 8" ID, 12" OD triple-wall tee (DuraChimney brand), I would be tempted to try it in the house, but probably shouldn't due to code issues. Could also use the tee in the garage to avoid cutting a hole in the roof. Trouble is that I don't think DuraChimney ever manufactured tees in the first place. If you find one, I might be interested.

Steinke

This is a very old post I started - and never really solved the problem either. I purchased a used bit stoker to put in the house, and the "smoking" handmade stove moved to the garage (for convenience mostly, not just cuz it smoked).

I recently attached the garage stove to an 8" interior chimney in the garage, but of course, since I built the stove with a 6" dia. collar, I have a few feet of 6" pipe above the stove before it increases to 8" diameter.

But I still have a smoke rollout issue when I open the load door. I know I have some excellent draft in this chimney, and it's clean. Cap is not plugged, garage is not air-tight, etc.

Is it possible that I need to put an 8" flue collar on the stove, and eliminate all 6" pipe? I didn't think a few feet of 6" pipe wouldn't make that much difference. I work with hydraulics for a living, and when running water in a pipeline, a few feet of smaller pipe does not have much effect on flow. Maybe gasses act differently than water?

Any thoughts? Is it worth cutting the 6" collar off and welding on an 8" collar, and eliminating all 6" pipe?

Steinke

If you only have a 6" collar coming out of the stove, I don't think the work to remove the 6" section would really be worth the effort. Sounds like the chimney might need a few extra feet added to the top, ... and a cap wouldn't hurt either. Sounds like a low draft issue ...... although I have adequate draft here, I sometimes will get the rotten egg smell when loading ... so I'd imagine if I were burning bit, there would be some smoke rolling out.

But I have a welder (I built the stove myself), and could change the collar to an 8" collar.

I could add more chimney pipe, but I'm already 2' higher than any roofline within 10' distance.

I know I have good draft, just wondering how draft and volume relate.

Can you have excellent draft, but still need more volume to contain the exhaust gasses? Is it analagous to pressure and flow in hydraulics (you can have adequate pressure in a pipeline, but that doesn't ensure that you have enough flow).

Steinke

I would think a larger column of warm air would create more pull. I've seen some posts here of chimneys that are gigantic, & they had to add an extra baro to control the draft. But then again something that big would probably hurt the efficiency, sending more heat up the chimney than you want. There's probably a reason most manufacturers stick with 6" exits.

when you have lower pressures, smaller diameter pipe will cause a substantial restriction in flow over the larger size. I've seen one section of 6" significantly reduce maximum flow over 8" at relatively constant pressure (draft). a smaller orfice whether moving a gas or liquid will always cause a reduction in MAX FLOW at a determined pressure; this does not mean that while burning under air restriction you will necessarily see any reduction in draft over the fire because of the low flow rate, but, when the door is open - as you found out - is when you will have the problem.

Try replacing the 6" pipe from stove collar to the chimney,, leaving the ONLY 6" item the stove collar.

If you open your air to the fire first, heating up the flue, 'revving up' the fire, is the smoke out the door less? You need a lot of flow to pull all the smoke from a fresh load of Bit coal up the chimney.. at least the rotten, nasty Bit coal I used to burn..

Have you put a manometer on the flue to see what the actual draft is?

Greg L

What is the total length of the chimney? Not only size but length of the chimney affects draft. If the chimney is only 10 feet or so in length I'll bet that's most of the problem.
Also, how much space is there between the baffle and flue exit?

steinkebunch wrote:I think I have what I need for the triple wall install in the garage. If I had an 8" ID, 12" OD triple-wall tee (DuraChimney brand), I would be tempted to try it in the house, but probably shouldn't due to code issues. Could also use the tee in the garage to avoid cutting a hole in the roof. Trouble is that I don't think DuraChimney ever manufactured tees in the first place. If you find one, I might be interested.

Steinke

Do you have code enforcement in Wyoming? It seemed like the land of the free and the home of the brave when I was there!