Blaze King 40 Smoke Smell Near Stove (No Visible Smoke) on Low Burn

I've priced 8 inch double wall pipe and chimney. I don't believe that is the problem, but what else is left? Unless it's seeping in though a window leak or something, which I don't think it is either. Looks like prices have come down on the stove pipe and chimney since I looked 3 years ago. Now, I'm looking at $2900 +tax. If this doesn't solve the problem, it has to be a faulty stove someplace. May a cracked weld or something.

 

I have a King 40 on a 6" chimney about 30' tall. Going on 6 years now.

If there was a crack, it would likely be a place where the stove would pull air in, rather than push smoke out. Especially if you have the stove dialed way down, the fire wants air and will pull it in however it can as long as the chimney is open.

See if the barometric pressure plays into the evidence of smoke. High barometric pressure will influence how well the chimney will draft as well as push the smoke back down once it leaves the chimney. There are times we can smell smoke in the house, but its clear that it is not coming from the stove or chimney.

Your wife may also be extremely sensitive to the smell. I can tell when the neighbors are burning if the wind is blowing the right direction.

 

Not me, not during a burn. When we hear about BK people getting smoke smell it's often an ashford but in all cases the first place to investigate is the chimney. So many folks don't meet the minimum recommendations in the manual. I would say requirements but BK is really squishy if it's a must or a may follow.

 

The smoke smell in my Woodstock was due to being at the min. height but having a few bends, 5 ft added to the top fixed the problem (and made the glass way clearer)

 

Sure seems like the weather could be playing a role in all this.

 

So, my 6" chimney is 19' from top of stove to chimney. I could spend more money on another section or two of pipe and support bracket and go a bit higher and see if it works, or, another question, would the same length of 8" pipe be "better" in the end. Previously, a poster, I don't remember who, suggested buying a length of 6" single wall and add it to the top temporarily, just to see if the problem goes away.

 

This is how you test for proof of concept. It can even be the cheaper HVAC ducting. I would love to add 3 more feet to my stack but doing so would trigger the requirement for roof braces for me as well as looking pretty dumb. You can only have so much chimney sticking out of your roof before it starts looking weird like a space antenna!

I'm not very good at chimney theory but using my old squinty eye I can see that the suck of an 8" chimney would be stronger than 6" if everything else is the same. It's like a bigger hydraulic piston. More force at a set pressure differential which is driven by temperature. So many variables though, like gasses cool faster in the bigger pipe and move slower for a given flow/burn rate. Ick. I'm sure other folks are more capable of applying the science.

You've basically rebuilt the whole stove at this point and the chimney remains clean but a new smoke problem is presenting. What has changed? Weather conditions do make a pretty big difference. I burn at 60 degrees ambient in the rain and also at single digits with wind. The BK thermostat does a great job at keeping the stove temp regulated despite the changes in draft from those temperature swings automatically.

 

Youve nailed my dilemma, nothing has changed. I've ordered everything for the 8" install. Crazy thing, today, not the faintest hint of smoke smell, confirmed by my wife as well. She's been watching the barometric pressure and temps the last 3-4 days, and she's convinced that's the culprit.

 

I'm beginning to question the thermostat on this BK. So, yesterday, 34° all day, and I burned using the low/slow concept all day. By 7pm, it was 30° outside, and 74° in the house, as it had been all day. I filled the firebox about 10pm, the stat set exactly the same as it had been all day. I would have thought I should wake to a 74° house this morning. However at 5:30am, outside temp was 29° and house was 68°. Wondering why this big drop when stove still had plenty of burn left in the firebox.

 

Hmm...is the air control, the one that the bimetallic spring controls, sticking?
That could cause an erratic burn, and an occasional "puff" in the firebox, which it doesn't take much imagination to see how that could cause some random smell...just spitballin here...

 

Okay, there is some maintenance for that thermostat. I just did mine this weekend. Turn thermostat cold until the flapper closes, remove cover with the two #2 square drive screws, and clean any dust off of the throttle blade and the "seat" of that blade. Then with spray silicone lubricant, lube the throttle shaft bushings. It's a very light spring tension that holds the throttle blade in place so it can get kinda sticky if the throttle blade shaft is not super free. I also smear a dab of copper antiseize on the spring washer that holds the knob setting in place. Be sure the intake flapper is closed when you replace the cover or you can leave it off and watch it work for fun.

I don't know if that has anything to do with smoke smell but I always notice an improvement in thermostatic action after this checkup.

Barometric pressure does affect draft strength. This is why folks at higher altitudes require longer chimneys. Lower baro readings mean weaker draft for a given chimney.

 

Spit away! I wonder if it could be sticking. I know when I turn it, it's very "tight" and squeaky. I'll see if I can post a video.

 

Dang, I'm thinking there might be a definite "sticking" issue going on. Interesting they put a label on it stating there's nothing serviceable hidden underneath. There clearly is.

Link to video of squeaky/sticky thermostat dial (Note, it seems you will have to tap the video two times to make it play):

 

Dab of antiseize on the spring washer will make that smooth as buttah.

 

Doesn't that knob/rod just tension the spring?
I'd think it'd be a lot more important for the actual air control device (flapper/door?) to move freely...

 

I'll see if I can look at it tomorrow. Stove's pretty hot for the night.

 

Honestly, not sure what it looks like in there yet.

 

You won’t be able to see the actual bimetallic spring and the little pinion gear arrangement but Brennda is right that the adjustment mechanism that’s scratchy is well removed from the flapper shaft.

 

UPDATE:
Well, even though I initially thought I had the weird smoke smell issue resolved after changing the cat, I was wrong, but continued my troubleshooting. Finally, I think I have it! I've never been happy with the ashpan on this BK 40. So much more inconvenient than my old stove which had a very heavy duty carry handle. What I tried to avoid, was carrying a smoking hot pan through the house and out the door to dump it. Even with welding gloves on, that sucker is frickin HOT! So, this year, I started by raking the ash into the pan, putting the plug back in the stove, and leave the ash in the pan until the next time it was due to remove a bit of ash. I would go dump the "cold" pan of ash, then rake the hot ash into the pan, replace the plug and repeat. Worked like a dream! I could go about 2-3 weeks on emptying 1 pan of cold ash.

One night last week, my wife and I were sitting here talking about this issue, and I it hit me how I had changed my method of dealing with ash disposal. I immediately got up, emptied the pan, wiped out the pan shelf, and, SHOCKER, we have not smelled anything since!! I think I can now say with 100% certainty, this time I think I got it!!

Moral of the story, don't leave any residual ash in the house. For me, when the stars aligned, it created the perfect conditions for two months of hellish troubleshooting and dealing with a stale smoke smell.

One other positive result of all this troubleshooting, at the advice of some on here, I actually added an additional 3 feet of pipe to my chimney. Holy cow!!! Amazing difference in the stove. Without moving my thermostat from my usual burning position, the stove completely changed it's behavior. immediately, coals began to glow brighter, and most amazing, within 4-5 hours, the glass had cleared off to almost clear except for a bit along the sides. The addition of pipe took me to just over 22'. Wish I had done this from the start.

Even though this stove works on a 6" pipe for me, I'd still go with, and recommend going with a 8" stove for the BK40 if installing a new chimney. I was happy with the performance on my existing 6" chimney, and even happier with it now that it has the extension. But, I can definitely see where an 8" could have it's obvious advantages.

 

So I take it the ashpan drawer, or whatever it has, is not sealed with a gasketed door...the ash plug has the seal?
Having used all types now, I prefer the pan in a sealed drawer. Next best is just leaving the ash build up and dig it out with the shovel when needed, but the obvious downside there is flyash floating away...