Charring Wood - Does It Really Work?

[BotetourtSteve]

Hi all. On the second season of burning with the Big 6 (Jotul F600). Have been real pleased with the heat output, especially with the blower. My only surprise/disappointment has been a lack of increased burn times and wood consumption over my old mama bear. I am getting 4-5 hour burns when running 400-550, and can restart with coals after overnight (8-10 hr) burns, but stovetop temps at that point are "only" 200-250. My current favorite method of burn is to fully reload before temps drop below 300 (hot bed of coals), as secondary burn returns almost instantly and I do not fool with adjusting damper (roughly 1/8 open). I use only seasoned hardwoods, mainly red and white oak.

Am I missing something here? I must confess that I have not bought into charring wood before turning down. When I tried it, all it seemed to me to do was burn up some of the wood quicker and make the fire harder to dampen down. Am I missing out, or doing something wrong by no longer attempting to char before dampering? Is it possible I have too much draft/should I consider an inline pipe damper? Was I simply oversold on burn times (was told "easy" 8-10 hr burns) and wood consumption? Any other suggestions?

Input welcome and appreciated!

 

[CTBurner]

Hi Steve.
I don't have the anwser, but I am interested in the response. I have a VC NC ENCORE and cannot got past the 6 hour burn. I am burning well seasoned oak (3 year seasoned) and ash. I have no problem getting everburn but it won't last more than 6 hours, I load the firebox up to overflow, then engage everburn then cut the air to none, it rumbles and stovetop is 550, flue is 350 with the infrared laser thermo thing. maybe the advertized 10 hours is out of the question but how about 7 and 1/2. any help would be appreciated. firebox will take 20" logs , mine are 16". is this the problem? if it is can i load chunks in the void area to fill space?
my chimney has very good draft, could it be too good?

8 inch flue into a 8 inch clay lined flue masonary inside chimney which extends up 23 feet above the stove top, the chimney extends down to the basement where the cleanout is.

 

[begreen]

Steve, there's nothing wrong with what you are doing. It sounds like you have excellent draft if the stove goes into secondary combustion without an intermediate stage. All stoves and flues are unique. There isn't one set formula. What works for your neighbor's setup may not work well on yours.

The operative word here is "burns" which is an ambiguous marketing term. I like period of meaningful heat instead. That would be from when the stove is above 300 degrees (warming up) to when it returns back to 300 degrees (coaling stage). This will be shorter than the advertised burn times which I think some makers measure from the moment the match is lit until there are just a hint of a glowing ember left.

To extend your burn times you might experiment with larger splits with smaller splits tightly packed to create a solid wood mass. And close the air control all the way down after about 15 minutes of good secondary burning.

I am curious about the flue on the stove. How much pipe is there from the stove to the cap?

 

[RedRanger]

Well that`s it then!! With real effort, I can get 7 hours max from my 2.5 cu.ft firebox insert. When I emphasize "that`s it". I will no longer complain. Because ya see guy`s, nothing but softwood here to burn, and that is mostly douglas fir.

Lordy, but I have to wonder what this beast would do with that sweet oak that you guys are privy to?

Thanks,, you have made me a very happy camper.

What size firebox are you guys talking about? 2.0? 2.5? 3.0?

I set mine up for the overnite burn at 11pm so when the wife gets up at 6am she is happy. She tells me that the blower has stopped, but the floors are warm and she is happy. And the top of the insert is still very warm to the touch.

Loading east/west-I place the largest piece (usually a round) at the back, then medium splits in the middle and smaller ones at the front. All coals raked to the front first. I get the front charred really good, and then shut it almost to zilch for air.

Works for this beast.

 

[CTBurner]

2.1

 

[Diabel]

CT,
At what stove temp do you reload?

While back I spoke with one of the VC dealer here & he said exactly what BeGreen said 10hr burn for these stoves with 2.1 box is measured from lighting a match to few embers left in the box.
When I get 8hrs I am content!

 

[CTBurner]

i fiqure from time i load up and put in everburn till stove is 250 with only a few coals?

 

[Diabel]

Hmm, with the wood you mentioned you should get longer burn. Check your gaskets, do not empty your ash pan too often (always leave some ash on the grate). Oh yeah, does your everburn sound like a jet or just a nice rumble?

 

[CTBurner]

like a jet, we do emty ash pan daily

 

[Diabel]

There is no need to empty the pan everyday, I do it every 4-5 days burning pretty much 24/7. Try placing your therm. on the stack & see what temps you get. I have two thermometers one on the griddle & one on the stack. I was educated recently here that if I run my stack temp at say 500-600* that is too hot - too much energy going up the chimney. So now I try to keep it around 400* (stack)

 

[bokehman]

we do emty ash pan daily

Ash is a really good insulator. It keeps the coal bed warm. I find in my wood burner that 2 inches of ash is a good amount, and, I just remove a few shovelfuls every few days, never empty it. I last put in wood at 7pm last night. It's midday now so that was 17 hours ago, but there are still lots of glowing embers just under the top fine layer of ash. The exterior is still at about 150ºF and after a bit of a stir this afternoon the embers will allow a speedy relight.

 

[jpl1nh]

we do emty ash pan daily

Ash is a really good insulator. It keeps the coal bed warm. I find in my wood burner that 2 inches of ash is a good amount, and, I just remove a few shovelfuls every few days, never empty it. I last put in wood at 7pm last night. It's midday now so that was 17 hours ago, but there are still lots of glowing embers just under the top fine layer of ash. The exterior is still at about 150ºF and after a bit of a stir this afternoon the embers will allow a speedy relight.

I completely agree. The only time I'm working hard to remove ash from my stove is in extremely cold weather when I need all the space in my firebox I can get. Otherwise, a couple of inches of ash make it easier to start up on reload and even out the heat cycles a bit better. In regards to the thread question, I char the wood to make sure my firebox temp is hot enough to sustain a long and clean burn before shutting the air back to it's final setting. This ensures enough heat so my cat fires off, or for a secondary burn system, so the secondary system works well. To maximize burn length, I use large pieces, rounds where possible and pack tightly with my biggest piece on the bottom as far from the air supply as possible. This forces the stove to burn its way through to the big last piece and slows the process.

 

[Backwoods Savage]

bokehman and jpl1nh really hit the nail on the head as did BeGreen! Much knowledge there!

 

[M1sterM]

Hi all. On the second season of burning with the Big 6 (Jotul F600). Have been real pleased with the heat output, especially with the blower. My only surprise/disappointment has been a lack of increased burn times and wood consumption over my old mama bear. I am getting 4-5 hour burns when running 400-550, and can restart with coals after overnight (8-10 hr) burns, but stovetop temps at that point are "only" 200-250. My current favorite method of burn is to fully reload before temps drop below 300 (hot bed of coals), as secondary burn returns almost instantly and I do not fool with adjusting damper (roughly 1/8 open). I use only seasoned hardwoods, mainly red and white oak.

Am I missing something here? I must confess that I have not bought into charring wood before turning down. When I tried it, all it seemed to me to do was burn up some of the wood quicker and make the fire harder to dampen down. Am I missing out, or doing something wrong by no longer attempting to char before dampering? Is it possible I have too much draft/should I consider an inline pipe damper? Was I simply oversold on burn times (was told "easy" 8-10 hr burns) and wood consumption? Any other suggestions?

Input welcome and appreciated!

In my experience, the smaller the splits, the more charring reduces the length of burn. In my opinion, one of the benefits of the top-down fire starting method is that it doesn't ignite all the wood at once, and the load lasts longer. However, it is a balance to get the firebox temp high enough to keep secondary combustion going. I've been splitting my wood really small to facilitat curing, since I'm relatively new to cutting my own wood, and am not very far ahead of the game. After trying some bigger, well-seasoned (finally) splits, I'm seeing slightly longer burn times.

 

[begreen]

In both stove cases, I would also suggest letting the stove cool so that it can be completely cleaned. Then get an assistant and darken the room. Take a bright flashlight and shine it into every corner and seam. Have your assistant tell you if any light shines through on the outside. Also, do the dollar bill test every few inches on the doors and especially on the ash pan door. Examine the gaskets on each door and look for any fragments of charcoal embedded in the gasket.

 

[BotetourtSteve]

And close the air control all the way down after about 15 minutes of good secondary burning.

I am curious about the flue on the stove. How much pipe is there from the stove to the cap?

She'll go to just a smolder when I cut it all the way down - blackens glass and only runs about 275. I leave it 1/2 of 1 shell ridge(Jotul owners know what I mean) open for my "all the way down".

I have a basement set up in a 2 story bungalow (sound familiar, hahaha) - approximately 30' stove to cap w/ 3 90 degree elbows along the way. Next time I get it cleaned, I am going to ask my sweep if he has a draft meter - I have an extra pipe damper I can install if needed.

 

[begreen]

Sounds like you are on top of things. Assuming no stove leaks, it might be worth trying the damper.