Harmon Oakwood first fire, not burning quite right...

[brider]

I fired up the new Oakwood last night to burn off the new paint before the REAL heating season begins (hasn't been cold enough here even at night for a fire), and I found that I couldn't keep a 500-deg temp without the main damper open and the air lever at max air.

Total chimney stack is 15', the manual says "Most stoves require a minimum 16' of chimney height for good draft". 5' of pipe inside is single-wall. Chimney is straight up, no bends.

I suspect my wood may not be perfectly seasoned, I did a fire in our traditional fireplace last week, and the wood was kind of reluctant to burn well.

In the stove, I started it with newspaper and pallet-wood (I cut up a pallet for kindling), and fed in bigger pieces of "seasoned" wood after it got going well. The pieces were maybe 4"x4"x16-18".

As I said, the fire got going pretty well with the damper and air on full open, but when I shut down the main damper, the fire settled to a low glow with occasional flames flickering, and hovered between 300-400 deg.

I filled the firebox halfway when I went to bed, and it all burned down to ash by morning.

I have another 18" of chimney pipe left, do you thing 18" will make a significant difference in draft?

What is a preferred steady-state heating temperature for the stove? I've read MANY opinions on this, but I'd like to think I should be able to maintain a 500-deg temp with the air lever, not with the damper wide open.

The only other parameter is my wood, I suppose I'll try the sanity-check and buy some dry wood from the gas station (and hope none of my friends see me) and see how IT burns.

Any opinions?

 

[Dill]

As I said, the fire got going pretty well with the damper and air on full open, but when I shut down the main damper, the fire settled to a low glow with occasional flames flickering, and hovered between 300-400 deg.

I filled the firebox halfway when I went to bed, and it all burned down to ash by morning.

That sounds about right for what I get for performance. The stack temps drop considerably when I close the bypass. Usually to the "creosote zone" on the pipe temp. I'm at the office so I can't tell you what the actual degree is.
Also I don't get the incredibly long burn times Harman says it will get. This is the day in the life of our stove. My wife gets up for work at 5 fills the stove, usually is plenty of coals that it takes right off, runs open for 20 minutes then shut down. I get up at 7:30 and fill the stove, usually some wood or a big pile of coals, same deal runs for while and then shut down. I come home at noon and fill it.
It gets filled again at 5:30, then once again at 11 when I go to bed. The longest I've got out of it was around 10 hours with the damper shut, the air midway, and full of oak. I don't like to shut the air all the way down because the inside of th stove gets creosoted right up and I'm afraid of what that does to the chimney.

Also I cheat and crack open the ash door to get a fire going.
Also with the damper closed you don't get flames to look at in the stove. You get a glow. And when its running good a gas burn every 30 seconds or so. Which is a quick flare of flames. Much like what my VC Vigilant use to do. But I didn't get the gas flare out of the vigilant just a glow.

 

[MishMouse]

The Oakwood has a similar combustion chamber design as the TL-300 so operations of the Oakwood and the TL-300 are very similiar.

The main thing with this stove is get the whole system hot enough to keep the draft going without getting it to hot to overheat the combustion chamber. Note: when the combustion chamber is activated "pulling the lever and causing the airflow to be circulated into it instead of up the chimney" it will magnify the temp by 2-3 times. So if your stove top is at 500 the combustion chamber will be from 1000-1500 degrees.

This stove works best with seasoned wood, if your wood is not split and seasoned you will have to play with the stove more often to keep the combustion chamber active. If you are having draft problems I would first have the stove installer do a draft check on the stove if it fails I would add additional pieces of Class A to meet that requirement either that or look into a draft inducer.

Please search the forum on TL-300, TL300 and TL 300 to find other posts on the TL-300 as they may help you further understand your stove.

 

[MishMouse]

As I said, the fire got going pretty well with the damper and air on full open, but when I shut down the main damper, the fire settled to a low glow with occasional flames flickering, and hovered between 300-400 deg.

If you have the air on full with the damper shut aka: the airflow going into the combustion chamber and your stove top temp drops below 400 you have a stall. To correct the issue open the damper "pull the lever forward and get the temps back up to 500 stove top, and re-close the damper. Both the TL-300 and the Oakwood are very big h of metal and it sometimes takes a while before you get it up to temp. You may have a few stalls before you get it going the way it is supposed to. Have un-seasoned or unplit wood magnifies this.

 

[MANIAC]

I am no expert on this stove but I think what you are both seeing for stack temps is not unusual with this stove. Very rarely do I venture beyond 500 and if so for a very short time. What I have found is a very thick bed of coals is a MUST before attempting to close the bypass damper. Once this is achieved stack temps in the 400 range and an active secondary burn are are what I am seeing. Don't get me wrong though it lasts a couple/few hours at best and then I believe you are more into what's referred to as the coaling stage.

I will however have to disagree with you on burn times which leads me to believe you have less than dry wood. I am currently burning some red oak that has been cut/split/stacked for well over 18 months. A couple weekends ago the nighttime temps were in the 30's in Maine, at ~10pm I put in 3-4 good sized splits (hardly full), closed the bypass damper and closed the air down to 1/4 and at 8am the stove had more than enough coals to rekindle a fire.

My setup is a top exit up about 2.5 feet to a 90 into a 20+ foot interior masonary chimney. The liner is I believe 8x12 and is clean as whistle the other day when I checked it.

I do have a couple video's of what I am seeing for secondary burns but they are large files and I don't know how or if I can load them here. If someone can tell me how I would be happy to post them.

 

[brider]

"Secondary burns"

Would a secondary burn appear as little jets of flame near the top of the combustion chamber? I didn't see anything in the manual that would lead me to believe I'd see any cool stuff up there, and I sure didn't during my burn.

Nobody really mentioned the effect of my chimney height, I'm going to guess that my 15' is not sufficient.

So it sounds a little like my stove is ALMOST operating like others with a Harmon, I just need to fiddle with the wood/draft/coal bed to be able to maintain good temps with the bypass closed and the air lever somewhere below full open.

 

[BJN644]

Like others have said, the bed of coals is a MUST before closing the damper. I know it can take up to 2 hours in my stove with the damper open and keeping the primary air controlled to prevent over firing, before I can close the damper. Sometimes I do see the little jets of flame coming from the burn chamber when the stove is really hopping. My usual stack temps are 300-400 deg. with the back of the stove at 500 deg. at times.

The back of the stove is where the heat is on an Oakwood.

 

[brider]

BACK of the stove? How come Harmon doesn't mention this? Sheesh, I might have designed it's location to move air around it's backside if I knew that---

Is 300 deg enough to get optimum heating? Is 400 enough? I was aiming for 500 deg stovetop temp.

 

[MANIAC]

Just so we're clear I am measuring with an external magnetic temp gauge on the stove pipe about 18" up from the stove.

 

[Dill]

1st off the begining of my first comment is quoted from the Orginal Poster.
The bed of coals is key. In fact the way my wife explains it, the first load of wood is "scarficed to the fire gods" before the damper can be shut.
And more heat does come off the back of the stove, so we have one of those heat operated fans on top of the stove. Which does 2 things it pulls heat from the rear and it lets me know how the stove is running.
Also the stove will retain heat for quite a while after the fire dies down. Not as much as a soapstone but better than most cast stoves.
Overall I'm happy with my oakwood (if I can slove the smoke issues I'm having this year), its does 90% of our heat. In a 1600 sqft 2 story log cabin, with 4 doorway fans. We burn 1 1/2 rubbermaid totes of wood every 24 hrs. Since I do my own wood, I always have a problem coming up with cords.

 

[BJN644]

BACK of the stove? How come Harmon doesn't mention this? Sheesh, I might have designed it's location to move air around it's backside if I knew that---

Is 300 deg enough to get optimum heating? Is 400 enough? I was aiming for 500 deg stovetop temp.

The way they tell you is the 28" of clearance required from the back of the stove.

I think with the Oakwood you might have trouble maintaining 500 deg. stove top temps. without overfiring because of the down draft design. Don't worry the heat is there it's just in the back, which does make it more comfortable in the room it's located in.

The Oakwood is one heat pumping machine, it's cold here in Maine and it kept me from paying the oil man last winter in my drafty old house.

 

[brider]

So, how effective are those doorway fans? Do they mount up in the corner, with a cord running down to a nearby outlet? Any brand recommendations?

 

[Dill]

I'd say very effective much more than the ecofan on the stove. The eco fan is really just there to show how the stove is burning and to let my wife explain engineering princples.
Ours are mounted in the doorways and yes with a cord running down. I have 4 total, (lets see if this works)
(ok that didn't work)
Basically half the fans blow in 1 direction the other half in the opposite direction. Hopefully circulating the warm out and cold air back to the stove.


Not sure if the 2 way airflow helps, but I do it anyway. The stove is at 1 end of the house in the livingroom which stays in the mid 70s in the winter and the comp room is at the other end and stays 60s ish in the winter. Since its a log cabin there is no sub floor and the heat rises well. Upstairs is usually in the 60s. Warmer in my daugthers room above the living room than mine. Also the chimney runs through the upstairs and gives off a decent amount of heat.

 

[N/A N/A]

To re-cap what the others above stated:
1. Burn small stuff fast and hot at LEAST on hour prior to closing the re-burn damper.
2. Get your stove good and hot (each stove and set up is different you got to play and figure yours out) min of 500 degree stove top. (in this warm outside air) Not pipe but stove top. + or - 500
3. Have a thick coal bed. The thicker the better. If less than two inches push the coals back around the throat of the reburn chamber.

If you do these three things you will be well on your way to figuring out your stoves ups and downs. And should have luck with getting re-burn. Also. dry wood your stove will like! Best of luck to you you got one kick a$$ stove!

 

[stanleyjohn]

I have the insert version of the TL 300 and i haven't seen stove top temps of 600 or greater.When i first light the stove the first wood load is just to get the temp up and develop a good bed of coals,damper open and air control fully open.Its IMPORTANT to have a good coal bed in order to get the afterburner running effectively.With the second wood fill up the heat and good coals gets the wood blazing in a hurry!maybe 5 to 10 min later i close down the damper and the after burner starts right up.You can see its working by seeing flames faning pretty good in the after burner chamber via the looking glass.At this time the stove top temp is between 450 and 525.The temp may increase abit with the afterburner running until the wood becomes more coal than wood.Since it isnt really that cold yet!i don't close my air flow much more than half way.When the weather gets colder the draft will get stronger and at that time the air flow will need to be closed more to control the fire.My chimney is higher than yours!its around 25ft and have more than enough draft!maybe to much sometimes.In your case i think when it gets a bit colder you shouldn't have much of a low draft problem.

 

[brider]

I never thought of the outside ambient temp as a factor in the draft. Good point!

I'm going to increase my chimney height by 18" this weekend and give a report on Monday. Temps are supposed to be much lower this weekend.