secondary burn - how much more efficient?

[aaron]

I can actually place my hand on the bare front steel of the fire box…

I wouldn't have any skin left if I did that on my Buck 74.

 

[haveawoody]

Fyrebug,

Quite small epa woodstove for me and i think some of the glass problems when you start a fire the secondary seems to spread that start smoke around lots more.
Wood I'm ok on so i know it's not the wood, most of that is cured 7ish years or more .
Pipes and draft both in great shape.
Once it warms up a bit the problem goes away, but each startup fire leaves just a tad more smoke residue.
Bet it's just a property of smallish epa stoves on startup.

I wouldn't say it was a gigantic pain over an older stove but just more regular glass cleaning, more in shoulder season for sure.

I replaced an old dino a few years ago and you are about right i use 1/3 less wood to do the same heating as before.

I think Whitespider is right about the new stoves and burning right ontop of the brick, always seems to be a some semi burnt stuff at the bottom after the fire goes out.
Old stoves for me atleast that never happened on a grate, just ash left.

 

[haveawoody]

Del_,

Yeah ive tried top down and same thing.
Smoke filled box on startup, clears quick as soon as the heat is getting going but not until.

I think the smaller epa stoves roll the smoke around quite a bit.
Old dino just belched it up and away.
More of a problem in shoulder seasons that when I'm burning real hot fires with real good wood.
The residue just tends to burn away then.

Anyone else with a smallish epa stove has glass issues in shoulder seasons?
Well more cleaning than usual.

 

[Whitespider]

I don't bother with cleaning the "glass"... why?
It's downstairs where I don't see it anyway... after all, it's a furnace.

 

[haveawoody]

Whitespider,

I just put on a ripper fire and that clears it for me.

Guess the wife is used to the old never clean dino so she wonders why.
Me i just have another beer and it looks cleaner

 

[stihly dan]

Late winter/early spring, I switched from an old “smoke dragon” (manually operated) furnace to an EPA certified stove I converted into a (manually operated) furnace. The old “smoke dragon” used a flue damper, the EPA firebox isn’t supposed to have one (I did install one just in case). I used it a bit last year, and I’ve used it a bit this year… there are positives and negatives to both.

When the secondary burn kicks in it produces a ton of heat… a ton, but it’s relatively short lived. Over-all I’d say I’m gonna’ use less wood, but I’ll be loading it more often. The old “smoke dragon” burned on top of grates, and the draft air was directed under them. This kept the firebox producing plenty of heat well after the fire had been reduced to a bed of coals. The new EPA fire box burns directly on firebrick, and once the fire burns down to a bed of coals the air is directed over the top of them, and the heat output becomes greatly reduced. I can actually place my hand on the bare front steel of the fire box… yet not on the stack. That tells me once the fire reduces to coals most of the heat is lost through the stack and not being transfer to the space around the firebox. Yeah, I still have coals 20 or 24 hours after starting the fire, burn times are longer… but “heating time” is shorter, a lot shorter. I’m not willing to say the EPA version is a better way to go… at least not yet.

Making your own doesn't count.

 

[Whitespider]

Making your own doesn't count.

Except... I didn't "make" the firebox on either unit, I simply built a plenum around both.
I didn't alter the way they operated, burned, exhausted or drew combustion air... so I believe it is an apples-to-apples comparison.

The old "smoke dragon" burned on a grate and had no fire brick, just a steel and cast box. It made quick heat and kept heating until the fire and coals were all but dead.
The new EPA firebox, has fire brick and no grate, and is (relatively) slow to come up to temp. It makes extreme heat for a relatively short period during the secondary combustion then reduces to about what the old box did. Once the the fire reduces to a bed of coals it heats poorly... it doesn't take advantage of that potential heat because it drafts over the top of them.

In my mind that's not necessarily "more efficient". I'd much rather have the steady, even, longer lasting heat. But, I'm not done playin' with it yet, I haven't tried using the flue damper yet, and it ain't been that cold yet...
All I'm sayin' is... I ain't willing to say the EPA version is the better way to go... at least not yet.

 

[cmsmoke]

I would go with what the majority of the replies here agree on...It's good advice. I have a secondary air stove and like it. It is a simple and effective way to extract more heat from any given piece of wood. Anytime I can get better efficiency from a fuel source, regardless if it is more heat or more horsepower...I'm all for it...especially if it means longer burn times or more miles per gallon.
I have no input or experience on the 2 stoves you mention. You will need to make that decision yourself.

 

[88bomber]

So I ended up with an Englander 28-3500. Found a brand new one for $900 out-the-door.

I figured it would take a long long time to recoup any savings after paying 1100 more for the firechief ($2000 out-the-door) ... based on my relatively mild TN winter climate and using the heat pump for fall/spring/warm winter days.

Thanks for the feedback.