Our wood stove's secondary combustion explained

Hello KZbinrs, a video on our wood stoves secondary combustion, with some explaination of how it is achieved. Our stove is made by CFM home products, and was purchased from Lowes. A Epa certified air tight, with secondary air inlets in the top of the fire box, allowing the high efficiency after burn. This technology allows a more complete burn, and less wasted energy going up the flue. Steel construction with a cast iron door, fire brick lined fire box, and a window for awesome fire viewing. A 6 inch flue connected to a 8x8 masonary chimney. The blower set-up I did uses a Dayton blower with a thermostat mounted to the heat shield, and a rheostat mounted on the wall to control the speed of the fan. When designing and constructing the hearth area I built a woodbox that is refillable from in the garage to cut down on the mess of bringing the wood thru the house. The stove has allowed us to save hundreds of dollars in heating costs. We enjoy burning wood, and I grew up with my parents having one. The work at the wood pile is worth it, when you can enjoy a nice fire! Thanks for watching, and enjoy in HD if you can. Please add me to your friends list and subscribe. Thanks, Enginenut :-)

[@LitheFider]

We (in north NJ) upgraded to the PE Summit Classic 6 yrs ago, with secondary burn, no smoke with top down fires showing no visible smoke. Heats our 28X48' barn frame home with south facing windows and stress-skin foam panels on 2 cords of wood a year, never use the electric backup. The stainless steel secondary air bafflebox (lasts longer than burn tubes, guaranteed for 20 yr? and has all combustion air passing by its airholes) sits above the fire and is easily removed when the stove is cleaned. We burn DRY wood (split wood to 3x3", enough draft to keep a 600 degr stack temp....and no "all night" damped burns) - Just had the chimney cleaned, an internal single wall that runs 22 ft to cathedral ceiling peak...they used a powered brush from inside the stove, just a thin fluffy deposit. Three years ago had roof replaced; the guys checked chimney and it was not worth cleaning. Prior to this, I had a Dutchwest 50k btu stove where for 6 yrs I did bank fires at night, cleaned chimney yearly and had perforation of acid creosote in 6 yrs- since then I am on same pipe...it's not burn time I am concerned with, but smaller hot fires that get temp up fast in the morning, and if no sunny day, may keep hot fire (3 3-4" splits at a time) to get house temp up before bed and be still 67 in the morning. IF sunny, my need no fire until next morning.

[@raidereddie]

That fire was so mesmerizing I fell asleep watching this video!!!

[@ZoneTelevision]

Love wood burning stoves used to own a Woodstock Soapstone stove.

[@enginenut]

Hello, the longest AVERAGE burn time I get with this stove is 7 to 9 hours. There are so many factors that affect the burn time, I feel the 3 biggest are firebox size, fuel type, and draft. People who get those 14+ hours usually have a stove with a large cubic foot box-say 2.5, mine is only 1.6. Second a good seasoned hardwood, I primarially burn red and white oak, finally draft in addition to the air control on the stove I have a damper on the flue pipe as well, which hepls on those windy days.

[@enginenut]

@MrGraygrizz Hi, most of our fires are for days, once the winter temps settle in. With properly seasoned firewood, secondary combustion, and correct stove operation we do not have any "campfire smells" in our home. Usually the smells like that are from incorrect stove operation forming creosote deposits in the flue as well as sluggish draft within the flue. Usually we only get a slight "woodfire" odor when refuling...but don't mind because of all the money saved in our heating bills :-)

[@enginenut]

The stove is made by CFM home products, and was purchased from Lowes in 2006, still working great, matter of fact its going right now!

[@MrStropparo]

Once you get secondary burning achieved, shut down the primary air supply almost completely. The wood will stop burning and smolder. The secondary burn will continue if the pipes are hot enough and the logs will last twice as long. It seems wrong but all the air will come from secondary air source and the smoke from the smoldering will ignite at temps near 2000 degrees. Try it after you have a raging fire for a few minutes and it's really hot. Play with primary till flames die on logs but keep coming out of secondary. No flames between logs and roof for a few inches. Hydrogen is burning from super heated air mixing with it. Easy way to get even longer burn times. Ember like smolder in bottom is all you need.

[@anthonyfryer742]

MrStropparo ...the primary intake..how does one control it. seems flames dies out?

[@MrStropparo]

Anthony Fryer 2 different air sources. Primary bottom air to start fire and get all wood raging with fire then shut primary and let the secondary top air do the work of burning the gases. Wood lasts much longer. close down the air on bottom of stove. So the stove becomes a vacuum starved for air and will draw it from the top secondary air tubes When this happens the fire on bottom becomes smoldering embers and the smoke rises and mixes with the super heated air coming in the top tubes and the smoke spontaneously combusts at a much higher temperature because it's hydrogen and other gases and it consumes all the smoke and burns very efficiently. Stove needs to be as air tight as possible. 2 different air sources. Primary bottom air to start fire and get all wood raging with fire then shut primary and let the secondary top air do the work of burning the gases. Wood lasts much longer.

[@anthonyfryer742]

MrStropparo ..Wow..You sir are wise ..truly It did work with a 2+ hour gain...Thank you

[@anthonyfryer742]

One thing is mandatory to achieve better burn is outside intake. 400-500 degree is the time to close the primary intake. I tried to damper down slowly and instantly, after 2 combustion barrel shot. The Coaling was much better with more ash. I still have major impoverishment to accomplish...It's not toss in wood make fire make me warm..... experience & skill are needed.Thanks again.!!

[@MrStropparo]

Your stove may need a touch of primary air to make it work instead of total shut down. So play with it a little. Enjoy. 😀

[@BackyardHomesteading]

Great video! Thanks for sharing.

[@firewoodguy2009]

you should first filler up with thin kndling let it burn for a while than fill the stove up with split oak logs

[@izzzzzz6]

The secret must be in the seasoned red oak, dam i don't have that here :)

[@daleval2182]

If you have white birch wood try that, it's amazing

[@enginenut]

@gabigowriel Hi, more or less the secondary air inlet tubes are some sort of steel tube with holes in it, but that is where it ends, the inside diameter of the tubes, how they are placed in the top of the firebox, and even the size air inlet holes drilled in the tube are all part of a stoves overall design. Smoke does not come out of the inlet tube because of the "vacume"/"draft" the stove creates while operating, pulling fresh combustion air in.

[@racinjason68]

Awesome!

[@peskybobcat]

I always seem to get some white smoke when doing this

[@goonluv]

Nice !!!!

[@jeffreyrichardson]

For a cleaner burn, more o2 is needed...The damper opening should be increased.

[@enginenut]

@firewoodguy2009 True, thats what I do when I light off the stove, this was a well established fire with a great coal bed ready for the nice hunks of oak :-)

[@enginenut]

The secondary combustion air can not be controlled, however the volume of secondary combustion air does change depending on how the primary combustion intake air lever is adjusted. The more intake air the more vacume/draft a stove will have.

[@enginenut]

@whitehat55 Hello, the stove is made by CFM home products, and was purchased from Lowes 6 years ago.

[@cocobonner9727]

when do you turn down the secondary combustion system. We have a defiant.

[@GrandpaBillDex]

Do you open the secondary air tube all the way

[@carolynvaughan5880]

Great explanation ! Great information! I am always trying to figure out how long I can burn efficiently and how low I can set the stove. Any thoughts?

[@tonyscarl6456]

I was looking to replace the overly expensive catalytic combustor for this unit, it took a few hours searching, I found that firecatcombustors.com makes the High Valley catalytic combustor.Mine was a WV-4150000034 for my High Valley catalytic insert. Hope I saved you a few bucks not having to buy through High Valley!

[@racinjason68]

What stove you have? I have a Lopi Freedom I just put in after Christmas and I am loving it! The secondary burn does keep me busy watching.

[@globalaccord8406]

Guess you meant "hypnotizing?" ;)

[@patrickdirks]

Hi, real curious to hear if all it takes to create that after burn are the tiny holes at the top.

[@MrLive123456]

Is there a separate air intake for the secondary burn or baffle system so that you can close down the primary air intake and still maintain enough oxygen reaching the baffle?

[@ratclifferob]

Hello great video, what heat is the hottest you recommend as some thermostats have different temperatures, some go up to 460 Fahrenheit and some 600 Fahrenheit?

[@Colwray1]

Do you/can you control how much air comes through the secondary air inlet? If you can reduce it for instance do you? Or do you leave on full air?

[@EsspressoMan1]

Its still burning to fast for an air tight wood stove. Secondary combustion is really not needed if Your burning hardwood. I burn white birch in my airtight woodstove and the fire lasts for 2 HRS before having to throw more wood on the fire.

[@mammasat]

you have to understand why this happens, and to understand it you have to study for a long time. It took me two years to understand

[@a6five]

So waching this video means nothing until we study it for two years? Cool. I'll get started.

[@pirate612]

The secondary air that's in the box at the top - does it come from outside the stove, via a hole in the side of the stove. Where does the air for the secondary burn come from? Is it forced in by a fan, or is the air drawn in and if so how.

[@enginenut]

The secondary combustion air intake is located on the back of the wood stove, the air is pulled in by the draft of the stove.

[@pirate612]

enginenut Thank you for reply. Your video is excellent. Have you ever thought of doing this kind of thing professionally and installing these things on older stoves? You should. Very good video and thanks for your response to my question.

[@TheCarnivoreDen]

What temperature do you run the TOP of this or any stove or whats the maximum cruising temperature for the TOP of this or stove is ? NOT the stack or chimney... Anyone?

[@Amotorcyclenut]

I have my stove set up with secondary burn. Mine likes to hang out at 700-900 degrees F with a stack temp of about 250 F. Secondary burn starts when the stove hits about 450 F. Here's the link to video kzbin.info/www/bejne/ionOc6WFl5KHaMk

[@GrandpaBillDex]

My question is how does the air get that hot that fast when pulled into the secondary tube. It's just a straight shot from outside to inside.

[@CraigArndt]

The air comes in at the outside temperature and early in the burn that cold dense air has lots of oxygen in it. As that plenum heats up, the fire brick radiates heat back into the stove and the metal absorbs it, its highly conductive. That ice cold air warms then quickly super heats, igniting the gas from the wood or smoke. Thats why brick is so important. I had one brick out of place and it through the whole stove off. Once I moved it back slightly, the next fire had no escaping flames and no smoke from the chimney, really remarkable.

[@MrLive123456]

Hi, does this air source for for the secondary burn require damper control during initial lighting or is a constant supply?

[@samanderson1564]

Why is the baffle insulation that just lays flat on top of the firebrick necessary

[@MrStropparo]

Sam Anderson so the secondary flames don't melt or distort the top of the stove at 1600 degrees.

[@vladipful]

how hot does the secondary air get

[@MrGraygrizz]

I got a question for you. You have stated that your parents had a wood stove growing up, and now you have one also, so it sounds like you have some years around them under your belt, so to speak. I was wondering, since I have not had a wood stove of my own before, after you have had an evening fire in it, and the next day it has all cooled down, do you have any problems with you house/home, smelling like a campfire the next day? Is that a problem with woodstoves? Just woundering, thanks, Tim.

[@pals2323]

What size holes did you drill into the air supply in the fire box for the secondary burn?

[@whitehat55]

Is this a pacific energy by chance ?

[@RandomEH]

mine has a cracked top brick and the secondary combustion does not seem to work well.... u think replacing the brick would help?

[@enginenut]

+RandomEH! YES!!!! That shelf can not be compromised in any way. If there is gaps between ANY of the bricks the unburned gasses (smoke) will go between and not have contact with the super heated air to acheive secondary combustion. All unburned gasses must go "around" the shelf to have enough time to come in contact with the super heated secondary air, for the efficient "after burn"- Happy Burning :-)

[@jackmyoff9879]

What is the LONGEST Burn time you have ever achieved. I am reading that its possible to get 14 Hour + Burn times but my max has always been around 8 hours, even with a fully loaded fire box. Which is not bad but, im wondering how folks are chieving 14+ hour burn times. Seems unrealistic to me.

[@aeropurtat]

like

[@426superbee4]

I like a wood stove, but they eat a lot of wood and become a slave feeding it and cleaning it out. There np in a clean burn if the wood is cured out rite with the rite air flow, wet wood, fresh cut wood need to be season or cured I'am so sleepy gn every one zzzzzzzz

[@adkinsmikkelsen4980]

I just love your project. On woodprix I've found great wood instructions to make it too :)