HELP! Excessive draft - need more control of burn rate.

[wood-fan-atic]

This is my insert - it is a "Flame 1.9-I" made by SBI, and it has a 2.3 cu.ft firebox. She burns well - too well, in fact. I have an interior chimney, the insert is in a formerly double open sided fireplace. There is only one air control (lower right on pic). When it is in the 'fully closed' position, there is still air feeding the firebox through a nickel-sized air hole on the sliding air-control lever. In the past, I have partially covered the hole with a magnet to restrict air flow in order to slow down the rate of burn. But, this solution was not ideal. I spoke to some techs at SBI, and they seem to think that due to my interior 2 story chimney (and the fact that the stove is only a year old, and the gaskets are all good and tight), that my draft is actually TOO good. Has anyone else experienced this problem? Since I still have access to the back of the insert from the back (double-sided fireplace), I was thinking about adding a flue damper just above the stove. There is limited room above the stove, so it would HAVE TO be installed right on the collar itself. It just seems to make sense that if I could reduce the draft a little - that I could control the burn rate better than I can now. Ive included a link to the Flame website as well. What to you guys think?

http://www.flame-intl.com/product.aspx?CategoId=7&Id=457

 

[Todd]

I don't know all the ins and outs of your stove but I'm guessing the reason why your magnet didn't fix the problem is because it has a separate hole somewhere for the secondary air tubes. You probably cut off the primary air? Once that tall chimney starts drawing hard it probably pulled even harder through those tubes. A damper may be the best solution since you have access to the collar.

 

[Shari]

What size liner do you have in your chimney?

 

[wood-fan-atic]

Todd- that is correct - the secondary air inlets are located in the rear of the stove - INSIDE the heat shield box.....i.e. - inaccessible.

Shari- I have a 6" SS flex liner.

 

[Shari]

Does your liner go all the way to the top of your chimney?

 

[Todd]

I've heard another trick is to crush down the mesh type caps little by little to help slow down excessive draft.

 

[wood-fan-atic]

Yes, Shari...it is a fully lined....probably 20' in total. Here is a pic of the back of my insert. I guess I COULD try to lift the liner a bit and squeeze a damper in there....I dont know,though.... the liner could be hard to lift - and Im a little reluctant to cut it.

 

[Shari]

Okay - I was thinking maybe you had what is called around here a 'slammer' install - you don't so that is good.

Do you have blockoff plates at the bottom and top of your chimney? If not maybe you are getting excessive draft from room air going up the chimney and as a result your stove may be benefiting (wrongly) with a draft from the room.

Just thoughts - take them with a grain of salt.

 

[raybonz]

Try burning larger pieces of wood.. Lots of small splits will make the stove take off, 3 or 4 large splits will burn much slower than lots of small splits..

Ray

 

[wood-fan-atic]

Okay - I was thinking maybe you had what is called around here a 'slammer' install - you don't so that is good.

Do you have blockoff plates at the bottom and top of your chimney? If not maybe you are getting excessive draft from room air going up the chimney and as a result your stove may be benefiting (wrongly) with a draft from the room.

Just thoughts - take them with a grain of salt.

I do NOT have a block-off plate, due to the fact that it is an interior chimney - and from what I have been told, the block-off plate is most beneficial to EXTERIOR chimneys (cold). I was thinking of installing one this fall - I have the materials on hand (sheetmetal, insulation). I guess it couldnt hurt.

 

[summit]

Lets get to the root of the issue: how are you defining "She burns well - too well, in fact"? burn times not what you expected? temps too high? There is always air flowing in, even thru the primary air control. even when you shut the primary down all the way, most (if not all) epa stoves' primary air controls have a stopper to keep a bit of it open at all times.

 

[pen]

Lets get to the root of the issue: how are you defining "She burns well - too well, in fact"? burn times not what you expected? temps too high? There is always air flowing in, even thru the primary air control. even when you shut the primary down all the way, most (if not all) epa stoves' primary air controls have a stopper to keep a bit of it open at all times.

+1

A 20 foot chimney isn't really all that tall and I wouldn't expect it to overdraft. Other than being new, are you certain the door is sealing well? Does the door stay evenly clean all over it's surface during the burning season or does it get brown / black in any certain places and not others?

pen

 

[pastera]

My insert whistles with the draft control closed down - 32' interior 5.5" liner

Block off plate is good for any install - stops air from flowing around the the liner (cooling it) and pulling cold air into the house

 

[Todd]

Looking at your new photos it looks like they used some kind of tape to attach the liner to the exhaust collar? That won't last and could cause a dangerous co situation.

 

[wood-fan-atic]

OK- answers- The glass stays as clean as one could ever expect (just some fly ash, or if a split happens to burn against it). Burn times - depending on species - fair, but not great. I can get overnight burns easy enough with any dry hardwood (ash,oak,locust) - with plenty of coals in AM for re-start, but true,meaningful heat is only 4 hours or so - with the bulk of the wood burning away in 3+ hours or so. The liner is secured with screws ,as it should be - the heat tape is just wrapped to seal any spacial leaks around the collar. The "door" that covers the primary air inlet does close completely - but has a nickel sized hole in it - so if an inexperienced operator didnt know any better - they couldnt "choke" the fire. The tech at SBI suggested that I cover the hole with aluminum tape. This would reduce the amount of primary air, but if excess draft IS my issue - it will then be sucked in thru the secondary inlets behind the stove.

 

[begreen]

I've never heard of 4 ft of pipe taking a stove from under-draft to over-draft. It sounds like there may be another variable involved. Drier wood?

 

[wood-fan-atic]

I've never heard of 4 ft of pipe taking a stove from under-draft to over-draft. It sounds like there may be another variable involved. Drier wood?

4' of pipe? Not sure what youre referring to.

 

[Todd]

I think I'd cut a 12" section of that flex liner and replace it with rigid and a pipe damper.

 

[wood-fan-atic]

I think I'd cut a 12" section of that flex liner and replace it with rigid and a pipe damper.

I think this solution is what Im leaning toward so far.....

 

[wood-fan-atic]

Ok - perhaps a stupid question.... how would you go about cutting the liner while its in place? Perhaps drilling a hole, and then using tin snips....would that work? Im not going to have much room to work up there near the old fireplace damper.

Would this work?
http://www.google.com/products/catalog?hl=en&q=6"+flue+damper&gs_upl=4374l10389l0l11921l14l13l0l0l0l0l219l1656l4.8.1l13l0&um=1&ie=UTF-8&tbm=shop&cid=17579119057578729959#

 

[begreen]

I've never heard of 4 ft of pipe taking a stove from under-draft to over-draft. It sounds like there may be another variable involved. Drier wood?

4' of pipe? Not sure what youre referring to.

Nevermind. I was reading two threads at once and got distracted by company. Sorry for the confusion. However, I agree that your setup should have the stove burning almost ideally. 20ft usually is not too much pipe.

The magnet covering the secondary hole sounds like a bandaid fix for the symptoms, not the problem. Has the stove been gone over by the dealer really well to make sure there are no air leaks or popped welds? Is the air control functioning correctly? Can you describe your burn process? What is the typical wood species burned and how large are the splits?

 

[wood-fan-atic]

BeGreen- I do not believe that there are any air leaks or faulty welds. The air control works exactly as it should (examined many times). Last year, I was using mostly borderline red and white oak (low 20s on the MM), and some nice dry ash and locust. Admittedly - the oak splits were a bit small (so they would season faster), but even with the ash and locust - the burn times were not great. As I said, it does put out good heat for several hours. But the majority of the wood mass is burned relatively quickly. Upon re-load, on a full bed of hot coals - I'll load the firebox N/S with 6-7 medium sized splits. They will light off immidiately, with the door closed and the air control open. Within 5 minutes, I can close it about halfway - and then about 10 minutes later - close it all the way. At this point, even with the air closed all the way - there still seems to be too much combustion. Within 2 hours, the wood has burned down to the point that secondaries are no longer visible.
Dont get me wrong - the stove is heating a 1600 sq.ft. home that is not wonderfully insulated, and only has 2/3 of the downstairs truly "open" floorplan. Even the second floor stays around 70* most of the time. My concern is that the bulk of the fuel seems to dissipate within the first 2 hours after re-load - and I am trying to figure out why. SBI seems to think it is due to excessive draft - and if installing an in-line key damper will slow that draft - it seems to me that the burn rate will slow down considerably. Does this make sense to anyone else besides me?

 

[begreen]

Try letting the coal bed burn down further and use larger splits, maybe packed tighter with the smaller splits. I'll bet you can add an hour or two to your burn times with this method.

 

[wood-fan-atic]

Try letting the coal bed burn down further and use larger splits, maybe packed tighter with the smaller splits. I'll bet you can add an hour or two to your burn times with this method.

This year I have 3 1/2 cords of ash and 1 1/2 cords of black locust (all c/s/s well over a year). Looking forward to improving the burn times this season. What about this damper? I think it will serve the purpose.

http://www.google.com/products/cata...=1&ie=UTF-8&tbm=shop&cid=17579119057578729959

 

[bpm44]

FWIW I really like simpson products and have used a lot of their stuff over the years, but I've noticed they seem to have their own sizing method. What I'm trying to say is that their 6 inch built in damper flue may not fit nicely with the actual dimension of your liner. My suggestion would be to buy a damper and put it in your collar or in a short piece of single wall pipe that actually fits your liner. Sure it's a bit more work to do it that way, but since you asked I thought I'd share. I do think adding a damper might help you though.