Little puff of smoke coming out of the insert top (extended insert) - Normal?

[joefrompa]

Hi all,

I have a Lopi Republic 1750 insert, been using it for about 2 weeks. Overall, it's been fantastic. I'm having a hard time getting the temp above 400 on a reliable basis, but that's another matter.

About 2 times now I've been starting the stove up and ALOT of smoke was forming inside. Simply my placement of newspaper/wood and perhaps a poor draft at start. I'm perfectly fine with it, I kept the door cracked and it DID NOT COME OUT from the door.

This insert has a firebox and then a "Shell" around it - basically another steel-plate box with a ~1" airspace that fits around the firebox, and then blower blows through it and out the top and sides to push heat out.

Well, from out of the shell on top or at the top of the sides, twice now, smoke has wafted out. It's only a little bit of smoke, it very gently wafts out, dissapears, and then it stops.

It seems to only happen during the initial start-up when the firebox is absolutely filled with smoke. The adjustments are correct for starting the fire (damper bypassed, air control wide open, door cracked).

I have 2 possible theories:

1. The smoke is so slow and thick that it gathers around where the insulated liner inserts into the firebox. It's not an airtight fit - so when the smoke has no velocity from heat or pressure, a bit wanders out. As soon as it heats up and the smoke is forced upwards, this is no longer a problem.

2. The firebox has a crack in it - This doesn't make alot of sense to me, since I never get any smoke/smell at any other time.


Is this normal? Does #1 sound right? It's literally so little smoke and it's gone almost instantly, but it's definitely coming from the shell around the firebox and not from inside the firebox.

Thanks all,

Joe

This happened to my wife as well, once.

 

[daveswoodhauler]

Hi Joe - I have a smaller Lopi, and have run into the same thing as you a few times...but it was my error.
When you are getting the smoke coming out, what are the temps outside?
What I do, and it hasnt happened again....
I take one sheet of newspaper and barely crumple it up....more like fold/crumple....light this up and hold it right at the top/front of the firebox to get the draft going...basically hold it there until I can't hold it anymore as its going to burn my fingers ;-)
After I do this, I then light my kindling and other newspaper, and leave the door open just a crack for about 2 minutes or so and then shut the door.
I think you just need to get a good draft going on your setup....good luck

 

[joefrompa]

Oh yeah, there is zero draft going on. The smoke is just curling around IN the firebox.

However, I wanted to make sure that it was acceptable to have a bit of smoke come out from obviously the back of the insert, rather than outside the door. Sounds like it's acceptable.

Joe

 

[begreen]

I wouldn't call this acceptable, but not because of the leakage, though I would seal up the flue collar. My main concern would be puff back. That smoke is unburnt wood and paper gas. Get enough of that in there and when it ignites there will be a mini-explosion. Try starting burning some balls of newspaper on top of totally dry kindling. Cabinetry shop scraps work great. So so carpentry and flooring scraps as long as they don't have a finish on them. If the draft doesn't dramatically improve in the next few weeks, I'd address this situation with a proper remedy.

PS: This is with a 16' flue, correct? I am not understanding why draft is poor with a newly insulated liner installed. Were there complications? Wet wood or kindling?

 

[joefrompa]

It's like 45-50 degrees out and probably windy when I've done some of these. It's 16' insulated liner....more like 13' actually.

Wood is probably slightly wet too.

Let me be clear: this is not ideal conditions or anything, I'm literally just asking if a very small puff of smoke coming out from the flue area is possible in a correctly installed, non-busted stove. Sounds like it is possible, under poor conditions, so I'm not worried about my stove.

 

[daveswoodhauler]

50 degrees out with slightly wet wood.....that will probably do it.
My chimney is a straight shot about 25'...if its only like 45 degrees out or warmer, I take a little extra time to warm up the flue and get the draft going.
Also, how is the clearance at your cap and above your roof line?

 

[Backwoods Savage]

Joe, it is called back-puffing. No, it is not normal and your stove is probably fine. It is lack of draft which causes this and sometimes in windy conditions the wind will have a downdraft and if you get it in the chimney, well, the smoke has to go somewhere. It does sound like you must definitely have a draft problem and maybe the cap is not just right allowing the downdrafting. Once you get the flue hot though, it should draft without causing the back-puff. Nasty thing it is.

And I will also have to add that poor fuel can be a big and perhaps the biggest part of the problem. Poor fuel = poor results. The wood will smoke more and not want to burn. Lots of smoke and as BeGreen stated, it is like a mini-explosion in there. Once you have the explosion, it probably clears the chimney and you will be good again.

If it happens again, open the draft a bit further.

 

[begreen]

If the flue is more like 13', that could be the issue. So so wood + so so flue = weak performance. If you want to find out, pull the cap and cram in some cheap 36" x 6" duct pipe into the flue top for a test.

Get some good kindling too. Put some good stout cardboard boxes in the car or truck and visit some cabinetry or wood flooring shops and some construction sites. scrounge up a lot of good kindling. Getting that flue hot before adding the iffy wood is going to help a lot.

 

[pgmr]

Well, from out of the shell on top or at the top of the sides, twice now, smoke has wafted out. It's only a little bit of smoke, it very gently wafts out, dissapears, and then it stops.

Unless this is a brand new stove and paint is still being cured on the outside of the firebox/inside of the shell, then I'd say you have a leak from the firebox to the shell space. The flue "adapter" (perhaps not the correct term, since some stoves require an additional bolt in adapter) or throat should penetrate both the shell and the firebox and be completely welded to both, preventing mixing of the firebox air and surround air.

In normal conditions, the firebox will be at a slight vacuum relative to the shell space, so air would leak into the firebox. Depending on the size of the leak, that could cause problems in controlling your burn.

Our old pre-EPA stove had a rotating damper built into the outlet throat. That meant there were two penetrations for the control rod, which was in the shell space. I don't recall getting smoke back out through those gaps, but I wouldn't be surprised if it did occasionally.