high efficiency arch

[Mark-NH]

Just read that Leader is working on their model of a high efficiency arch. I assume it will be based upon the same principles that the Force 5 uses.

To me the exciting point of these high efficiency arches is drastic reduction of wood needed for the season. I'm not getting any younger and I've always considered putting up the 8-10 cord of wood the biggest challenge each year. The rest of the to do list I can peck away at.

If I'm loading my arch every 10 minutes now and if one of these new arches even doubles that time (every 20 minutes) without decreasing boiling rate, I am looking at a lot less wood. Probably not half as I'm guessing you have to put a full load in each time you fire with the high efficiencies.

I've read claims of up to 45 minutes between loads. Do we have anyone out in Trader land that can substantiate this or give us a real world figure.

[PerryW]

I'll believe it when I see it.

I always figured wood stoves were something like 75% efficient, so I would assume standard evaporators would be roughly the same.

I can't see how the efficiency can increase that much since you can not exceed 100% efficiency without violating the laws of Physics.

[jason grossman]

all of the new evaporators are based on gasification wood boiler technology. i saw the first ones 15 years ago. they are efficient( not as much as hyped!, but nothing ever is) ever seen a gasification boiler melt down when the power goes out and the fans stop!!!! lots of heat and nowhere to go!!:o

[Grade "A"]

I saw the force 5 go for 40 minutes between firing at maplefest in vermont this spring.

[Brent]

Evaporators will never come close to the efficiency of a modern wood stove.
The stack temp on our Blaze King stove is about 300 degrees 2 feet above the stove. There's 8' more of plain black stove pipe before it hits the roof jack and goes to double wall. Up on the roof we can put our hand in the stack and it's only warm. Blaze King claim the EPA test earned the 92% efficiency rating.

On the other hand the evaporator is 975 to 1150 degrees two feet above the evaporator and unless you've got an air injection system above the fire, you're letting a huge amount of wood gas go up the stack unburned. The Force 5 and similar rigs likely hit numbers like or better than the Blaze King, but a big part of that heat goes up the stack too. If the flue pan was 50% longer and properly partitioned, you could absorb more heat before the gasses went up the stack, but you'd never be boiling way back there, just preheating.

[syrupkid]

lapierre claims 85% efficency with a force 5 while a normal wood fired evap gets some where around 45% the main efficency gain comes from the extra air injection with all that said it is almost impossible to get above 95% efficency because above 95% condensation in the exahust occurs. so........ i figure i was getting 15%-20% if that on my flat pans i hope my new evap gets about 45%

Joel

[nymapleguy607]

I don't think that it is fair to compare a woodstove to an evaporator. The woodstove doesn't put out nearly the BTU's of the evaporator. I think that if you ran a wood stove as hot as an evaporator the efficientcy would drop like a rock.

[brookledge]

I agree with nymapleguy there should be no comparision to an evaporator and a wood stove. While it is nice to increase efficiency the two operate differently. A wood stove works by giving off radiant heat and a slow small fire is all you need. An evaporator needs flame and hot gasses all the way through the flue pan. You can have a fire box full of hot coals and it will boil in the syrup pan but will just simmer in the flue pan.
Keith

[Brent]

I suppose we need to ask what you mean by efficiency. Are you trying to measure how much stuff goes up the stack unburned, ie wasted fuel, or are we trying to measure heat transfered from the fuel to the objects to be heated ie room air for the woodstove and sap for the evaporator.

To me heating sap efficiently is a factor of getting the hot gasses in contact with a huge surface area in the flue pan, and essentially the lower the stack temp the more heat has transferred into the pan. A fellow I know got a Maxi-flue from Leader last year and with no adjustment to his oil burner his stack temp dropped 45 degrees ... he was thrilled and at the end of the year could count the gallons of syrup to gallons of oil as a big improvement.

For us wood guys the other part, burning all the fuel, seems to be a factor of getting enough oxygen to the hot gasses to complete combustion. Here the wood stove and the Force 5 are doing the same thing. Air is introduced above the fire to create turbulence and burn nearly 100% of the wood gasses. Eventually all those guys putting blowers under the grate are going to realize that the fire is hotter and the boil is better but more wood gas goes up the stack unburned and you'll be putting a lot more wood in front door. Bin der, dun dat.

[brookledge]

Brent
Well said
Keith

[KenWP]

If it wasn't needed to have the flue pans boil so hard evaporators could be made to work on very little wood or even oil but when you need so much heat things change. These new high efficency furnaces have plastic stacks even but you also need a floor drain for the moisture. I do know that with a new oil furnace I need a new stack with pure SS becasue of the moisture problems but it also has to have a all fuels stack due to being dual fuel.

[danno]

And it's not just a matter of throwing air above the fire and presto, efficiency goes way up. There is some real science in how much air, where, etc, etc. Air tight arch and proper firing methods are also pretty critical.

I attempted air above the fire box - and failed. Will try again this year. Still think good wood is also a critical component.

[Brent]

Yeh ... trial and error.

Last year I put two pipes in across the top of the firebox with holes pointing down and put one small blower on each. The flames got more white/yellow in colour, the stack temps went up a bit and the fire was noisier, sort of rumbling. The best part was that it seemed to be using less wood. I did not have to put in wood as often. I never got enough out of the little blowers to cause back drafting. This year I've got a 3/4 Hp higher pressure blower and plan to put in about 6 pipes with a vari-speed on the blower to try to find the sweet spot.

We'll see. So far it works perfect ... in my imagination!

[3rdgen.maple]

Well after Dr. Perkins directed me to an article on tapping red maples I was looking for I came across this article you guys will be interested in. Here's the link http://www.uvm.edu/~pmrc/Combustion.pdf

[PerryW]

yeah, I guess the other big difference I hadn't thought of between a woodstove and an evaporator is that...

With a woodstove, there is no such thing as waste heat, since producing heat is what you are trying to do.

Wheras, with an evaporator; any heat that does not directly cause evaporation (like radiant heat, or warming up the air in the sugarhouse for example) is waste.

[nymapleguy607]

It seems to me that in order to increase the evaporator efficientcy you need to keep as much heat as possible under the pans. I agree that over fire air is important to getting the most out of your wood but I think more needs to be done to keep that heat in the arch under the pans. I want to try and reduce the gap under the rear of ny flue pan to about 4" and see if I can hold more heat under the flue pan also if I can insulate the sides with something to reflect the heat back under the arch. I would love to see my arch run as cool as an oil fired rig
Can anyone with a high efficientcy arch tell me how warm do the sides get?

[WESTVIRGINIAMAPLER]

I think it is all great except the price. It is unbelievable what the Force 5 arches cost. Appears Leaders new arch will be a lot cheaper as it was field tested this past spring, so it will likely be at least next summer or fall before it becomes available for sale as they will want to test even more of them this spring with any changes they may decide to make to it. If it is cheaper, it likely means it is not as efficient as the Force 5, but not all of us can make the investment a Force 5 costs.

[Brent]

Jeff

there is another thread going here where someone wants to keep a good boil going all the way back in the flue pan. There is a real trade-off when you start trying to do that. You've got to have more air flow to carry more heat further back, and then up the stack. If you've got unlimited wood or oil, go for it. I'm looking at my small bush and in a year or two I'll need to start cutting the goose that lays the golden egg, or buying firewood. So I'll be happy if I get a rapid boil in the front 1/3 of the flue pan.

I think most up could do better trying to keep more heat in the arch. Better insulation or reflection. I'm seriously thinking about insulating at least the back side of my flue pan and the back side of the hood. Also a lot of heat lost from the float boxes. I already wrap them and cover them.

Of course the grand daddy of them all for saving energy is a good RO

[nymapleguy607]

Brent
You do make a good point. that you need a good draft to pull the heat and flames back
I was thinking that by closing down the rear gap to help hold some heat and running forced draft below and above the grates, you would keep more heat under the pans, and by holding the heat in you can keep the combustion gases hot allowing them to mix with the injected air and burn the smoke completely
I am like you, it works in my head

[Steve O'Farrell]

The Force 5 arch is the result of observation and science.
It did'nt come easy. The principal goals, were to manufacture the real first
eco energetic wood fire arch.

[3% Solution]

Hi all,
From what I can figure with all this talk about being more efficient and adding air is a little thing known to the fire service is "Flashover".
Flashover is the ignition of a rooms contents after those contents have reached their ignition temperature.
I have been in a "Flashover Simulator" and it is pretty neat, neatest thing I have ever seen.
Now what I was sitting in, is a basically a woodstove or an arch.
I was able to watch the solid wood off gassing and as the air got filled with gasses and fine particles (smoke) the vent was opened, air was introducted and there it was a flashover.
We measured the temperature of some of the flashover (called snakes and black fire), 1800*, less than 16" above our heads.
I have looked into, from the stack end, an evaporator and what I saw was a constant flashover in and around the flues.
So, I think this is what is happening and what the strive is in manufacturing more effecient evaportors.
Why now, technology is getting better all of the time.
We are understanding the effects of fire and just how it burns.
With the proper air combination and fuels combination I bet an evaporator can be made that would be 90% efficient.
Now, how much do you want to pay??
Just my thoughts.

Dave

[danno]

Yeh ... trial and error.

Last year I put two pipes in across the top of the firebox with holes pointing down and put one small blower on each. The flames got more white/yellow in colour, the stack temps went up a bit and the fire was noisier, sort of rumbling. The best part was that it seemed to be using less wood. I did not have to put in wood as often. I never got enough out of the little blowers to cause back drafting. This year I've got a 3/4 Hp higher pressure blower and plan to put in about 6 pipes with a vari-speed on the blower to try to find the sweet spot.

We'll see. So far it works perfect ... in my imagination!

Brent - what did you use for pipes? I put 5 pipes with holes pointing down at an angle over the top of my fire. My manifold feeding the pipes lasted, but my pipes were toast by my 3rd boil.

[WESTVIRGINIAMAPLER]

Try to cover the pipes or square steel tubing you are using with a layer of 1" ceramic blanket and they should last for many years.

[nymapleguy607]

Brandon
How well are the sides on your inferno arch insulated ?
Do they stay cool enough to put your hand on them ?

[Brent]

Dano
I got the pipes from the folks that sell and service wood and natural gas stoves. These were the pipes that run the gas into the stove and came with a half dozen or so small holes in them. Picked these hoping they would stand up ... and they did . ... so far. Had about 10 good burns with them.

I'll be looking for something cheaper this year. I have a customer that makes parts for barbque makers and will be asking him for some tube or recommendations.

[WESTVIRGINIAMAPLER]

Jeff,

No, they get very hot. I only have 1 layer of full size firebrick and no insulation behind brick. I hope to redo the arch in a year or two and add 1" ceramic blanket or archboard behind brick, likely archboard.

[ennismaple]

With the proper air combination and fuels combination I bet an evaporator can be made that would be 90% efficient.

I was told by Lapierre that they did an efficiency test on the Force 5 for the EPA and got an 86.5% efficiency rating. Of course that's under ideal conditions and in practice we won't see results that good but it's a significant improvement over what we've used in our camp for the past 35 years!

[KenWP]

If you could find ceramic tubeing it might last longer or cover the tubes with foundry cement. There has to be thick wall metal tubeing made someplace.

[Brent]

Somewhere on the Blaze King woodstove set up there was an explanation of how the EPA test is done. From memory the wood must be square hewn douglas fir, dried to something like 20% moisture and periodic tests for emissions. Not quite as ideal as I would have expected .. ie hardwood etc.
But that's they way they test all of them so at least the playing field is levelled.

[Gary R]

Here's a picture of my air over fire manifold. It is all stainless. I don't believe there will be any problems of burning out. Stainless pipe is used in industrial settings. It should be available from the plumbing supply store. As others have posted in the past, the manifold could be made out of mild steel. You can cover it with a coating of refractory cement. The pipe nipples could stick out over the fire.

[inthewoods]

just finished bricking my arch today. started building just before xmas, it was alot of work but a fun project. hear is one pic,to see more pics go to my photobucket and goto 3x8 custom built intensofire.




http://i628.photobucket.com/albums/uu5/wagnersinthewoods/3%20x%208%20Custom%20Built%20Intensofire%202010/100_1596.jpg

[johnallin]

inthewoods,... that thing is beautiful.

[C.Wilcox]

inthewoods-

That thing looks awesome. Did you have access to one to take your measurements from or did you come up with it all from photos? Either way, it's impressive. Promise you'll post photos of it in action this coming season.

[3rdgen.maple]

sweeeeeeeeet rig. Be sure to post the results of how she boils.

[Bucket Head]

Inthewoods,

Thats a good looking arch! Very nice.

What are you using for a blower? Also, why did you go with air nozzles at the front and back and not all around the firebox? Do the factory forced air arch's only have air at the front and rear? Just wondering.

Thanks,
Steve

[maplwrks]

Very nice job, let us know how she boils!!

[DanE.]

Wow, that is really nice. Tell us about it.

[jdj]

If it works as good as it looks you should quit making syrup and start building arches, probably make more money:) Awesome job!!!!!

[Gary R]

Wow! That is nice. What are the three rods on the side for? Some kind of damper control? I know what to shoot for next:)

[Rhino]

You are very talented with metal work!!! Looks factory made to me!

[Loun]

I am extremely new to this game, so new in fact that I dont have an arch of any kind setup yet :) Likely this season I will be going with the uber non efficient cinder block and brick method and hope I can scavenge enough wood for what I need without spending too much $. However you all talk about efficiency and one thing that I dont think has been mentioned (unless I missed it) was a thermal coating like we would use on exhaust pipes and manifolds for modified cars to keep under hood temps down and increase exhaust flow by keeping exhaust temps up.

The coating is something you brush on and then bake in. It works extremely well and I believe temps of 300 degrees was all that was needed to bake it on. Is this something you guys currently employ? I would have to find the name of it but its available for easy purchase.

-Lou