My smoking Lopi Answer

[K2Orion]

I'm here to beg for answers.
We have a brick fireplace on an outside wall of our house. It has a 24"x24" opening and is 18" deep. The damper was about 12" above the top of the opening. It has a ~7' of 8"x12" clay flue. It smoked every time we used it. So it didn't get much use.
In the Fall of '09 I installed my first insert. The Robin Hawke smoke dragon insert that is still in my signature. It heated our home adequately for 4 years. It had a by-pass damper. It was installed with 8' of 6" stainless liner and panels around the face of the insert. It drafted well (I guess). With the damper open and the air inlets open, it would take off from minimal coals when reloading. But it smoked. We could not burn with the door open, you know, for that crackling fire for guests and the cave man appeal of staring at the flames. It would smoke almost as bad as the open fireplace did. I added 2' single wall to the top of the stack in the hopes that it would increase draft. The difference was negligible.
Then in the Fall of '13 I scored a Lopi Answer on Craigslist. Its what I really wanted originally but couldn't justify the cost of to the CFO. I installed it with a block off plate and the same 10' of 6" liner. I use about the same amount of wood. But I get shorter burn times because of the smaller firebox and the inability to smolder the fire like I could with the smoke dragon. I can tolerate this because it is a better looking insert. Bigger window, better blower, neat-o secondary flames. I like it. But it smokes. Still can't burn withe door open, not that I want or need to. But sometimes on reloads it will puff out enough to trigger the smoke alarm. Not cool when it goes off in the evening when I'm loading before bed and it wakes up the whole house and the dog goes b-a-n-a-n-a-s.

So Lopi Answer owners/ experts, HELP. Please.
Opening various windows gives no benefit. Do I need more flue?
I had a thread about utilizing the outside air kit.
https://www.hearth.com/talk/threads/lopi-answer-insert-oak.76847/#post-1558301
Would that help?

 

[DBoon]

I have a Lopi Answer in a similar setup.

I'm not sure what you would consider good burn times, but I can get 3-4 hours of good, usable heat (400 degrees F stovetop) and a reload on coals after 10 hours. I fill the firebox pretty full with squared off splits, and only reload when down to coals and about 250 degrees F. If you are reloading on large amounts of coals or a hotter, fuller firebox, I could see that you could get some smoke spillage. To avoid this, try opening the door slowly - just crack it for 15 seconds or so, then pull it open really slowly. That should help.

You should not burn this stove for an extended period of time with the door open. If I did this, I would have a raging inferno within 15 minutes. I suspect you might have wet wood, which may contribute to smokiness as well.

 

[Grisu]

Not sure what the manual says but most inserts require at least 15' of flue to burn properly. 10' won't cut it. Do I read that correctly that the liner is not insulated although it sits in an exterior chimney? That will also impact the draft. You can look into connecting the liner to a class A chimney pipe, there are special adapters for that. But you will need to add quite a bit of class A to get the insert to draft properly.

How dry is your wood?

 

[K2Orion]

15' ?? Really?
I guess I need to read the manual on the Lopi site.
Not insulated. Hard to insulate between O.D of the 6" and I.D. of 8x12. I guess I could try.
2-3 year split and stacked red and white oak and hickory.

 

[claydogg84]

15' ?? Really?
I guess I need to read the manual on the Lopi site.
Not insulated. Hard to insulate between O.D of the 6" and I.D. of 8x12. I guess I could try.
2-3 year split and stacked red and white oak and hickory.

I couldn't do the insulation wrap either because of the flue size, so I did a pour down insulation.

 

[K2Orion]

(broken link removed)

The manual says minimum 15' of flue. I guess I'll be shopping for class A and an adapter.
No surprise the fireplace smoked with only 7' of flue.

 

[DBoon]

If you only have 7' of flue, that is going to be what you should focus on. I have about 12' of flue pipe and that works fine, but I don't start a burn when the temperatures are above 45 degrees. Insulation around the flue pipe will help to maintain the draft on a short flue, but that will not be the magic cure all for a 7' flue.

Your wood supply may have something to do with it also. Hickory takes a long time to get started and flame (not smoke). I only use hickory on reloads on coals in a 350 degree firebox. Otherwise, it will smoke for hours before it can really get going. I don't burn oak, so I can't comment on that wood.

Once you get the install tuned up, you will be very happy with Answer, so stay with it.

 

[K2Orion]

Update.
I added a 3' piece of class A to extend my flue. Now I have 14.5' of flue from the top of the stove. The stove draws much better and no longer smokes out the door. Reloads on minimal coals works better too. Cracking the door helps restarts tremendously, before it made almost no difference. I still plan to insulate my liner, but that will be a project for this summer.

heres a link to the manual
(broken link removed to http://www.lopistoves.com/TravisDocs/100-01166.pdf)

 

[begreen]

Thanks for the update. These stoves typically want 15ft or more chimney to function correctly. You should note improvement all around now.

 

[DBoon]

I think you'll really like that Answer now that you have the right flue setup for it. It's a good little stove that puts out a lot of heat for its size.

 

[newatthis]

Great update. I didn't realize that inserts had greater draft/flue requirements.

 

[begreen]

They don't. Most modern stoves are tested with and require a 15ft flue. The Answer's flue requirement is the same whether it is installed freestanding or as an insert. Note that there are a few exceptions to the 15ft requirement in both freestanding and inserts.

 

[newatthis]

I see; misinterpreted the comments. Does flue length minimum vary with firebox size?

 

[begreen]

I see; misinterpreted the comments. Does flue length minimum vary with firebox size?

Not really. My theory is that it has more to do with air passage length, routing and manifold size. The longer and narrower the secondary air passage is the stronger the draft will need to be to pull the air through. More 90 degree turns will increase resistance too. PE stoves can often get away with a shorter chimney because they have a wide secondary tube in the rear of the stove that goes straight up to a wide secondary channel built into the baffle. Only one 90 deg. turn. A worst case, theoretical scenario would be a stove that intakes air in the front to a common manifold, then splits the secondary air off the the rear, up the back of the stove, off to two side manifolds and finally into tubes. That would be six 90 deg. turns. Fortunately I don't think any stove mfg. does this for exactly this reason.