Central Boilers claims + maximum load size

[rschoensta]

Central Boiler is now claiming 85% efficiency for their e-classic boilers.
(And implying this is overall since, they claim the combustion efficiencies are almost 100%).
At the same they indicate that when the stove is burning at 150,000 Btu's output the stove will burn for 8 hours.
All of this from their website.
http://www.centralboiler.com/e-classic.html
Note that the overall efficiency values also appear on the EPA website.

So here are my computations.
Firebox = 27 cu ft or .21 cords.
1 cord of hardwood = 22 million btu's.
.21 x 22 million = 4.62 million btu's potential when fully loaded.

8x150,000=1.2 million btu's.
1.2/4.62 =
Overall efficiency = 26%.

Is my math is wrong here?
If not where does the difference come from.
Does central boiler recommend loading the boiler significantly less than full.
If so what is their recommendation.

Also has anybody ever tried burning the eclassic 2300 with a completely full firebox.
If so what were the problems if any.
If not what's the size of the average load during the coldest weather.

 

[stee6043]

I've seen folks on this site describe the differences between "combustion" efficiency, "system" efficiency and even "boiler" efficiency. So my first question is what type of "efficiency" is Central claiming to be 85%?

And since I've never seen one of these in person I'd like to say....DEAR GOD.....that is one huge firebox! 27 cubic feet? Really? Wow. I think I Have just over 6 cubic feet....and I feel like that is a fair amount of capacity...

 

[rschoensta]

re Efficiencies claimed I am guessing the following.
Combustion efficiency - almost 100%
Total Heat transferred to water within the boiler - 85% efficiency.

No figures for overall system efficiency which would be beyond their control I would think.

 

[DaveBP]

How advertising people come up with their sales claims usually requires the use of long sterile gloves, not mathematical analysis.

 

[logjammed]

Hey coalman, i am going into my second year with the e-classic , and second year in my 40 year old life burning wood. Note that I have never used another wood burning appliance. July of 2007 i had one fill of oil $1000. (250 gallons OUCH!). 1877 farm house 1600 gallons avg. annually. With pending state and local regs. I jumped into the wood game and have learned quite a bit, and my first year was a success. I did not bother neighbors and the house has never been warmer. As far as centrals claims , I have never done any calculations as far as heat load or efficiencies. My system does work for me and the unit does easy overnight burns in the dead of winter on dry pine 3/4 full fire box. I don't know , but i would imagine that even the best and cleanest units out there put into all kinds of various setups would come up with different efficiency #'s. That being said would it be correct to look at and believe any manufacturers claims? I wish i could have an engineered system ,but i think it would be pi$$ed away with my old house. I burned approx. 10 cords and i also have a zone to my 2000 square ft. shop. I did have some problems with the unit and central did take care of that and it did not effect performance or usage.

 

[shagy]

Central Boiler is now claiming 85% efficiency for their e-classic boilers.
(And implying this is overall since, they claim the combustion efficiencies are almost 100%).
At the same they indicate that when the stove is burning at 150,000 Btu's output the stove will burn for 8 hours.
All of this from their website.
http://www.centralboiler.com/e-classic.html
Note that the overall efficiency values also appear on the EPA website.

So here are my computations.
Firebox = 27 cu ft or .21 cords.
1 cord of hardwood = 22 million btu's.
.21 x 22 million = 4.62 million btu's potential when fully loaded.

8x150,000=1.2 million btu's.
1.2/4.62 =
Overall efficiency = 26%.

Is my math is wrong here?
If not where does the difference come from.
Does central boiler recommend loading the boiler significantly less than full.
If so what is their recommendation.

Also has anybody ever tried burning the eclassic 2300 with a completely full firebox.
If so what were the problems if any.
If not what's the size of the average load during the coldest weather.

The Epa rates the efficiency of the furnace not the manufacture. Go to the EPA'S web site. Some very good info there

 

[altheating]

I spoke to a e-classic user this fall at a trade show. He claimed that he replaced a standard central boiler with a e-classic and he now burns just as much wood with the new eclassic as he did with his old style central boiler. If his claim is true, and I have no reason to believe he lied to me. Either the old central boiler was way more efficient than we think or the eclassic is much less efficient than they claim. Since we all know how inefficient old non gasification OWBs are, then the later must be closer to the truth.

 

[sgschwend]

I just read the EPA stuff. As far as I can see they don't indicate which stove is on the graphs.

In the EPA test the working volume was measured to the top of the door.

They do list mfg stove models that meet the different phase standards. The standards are based on emission per heat output of a stove after it has been brought up to working temperatures.

The EPA efficiency numbers vary depending on the fuel load/type. The phase 2 passed E class stove models efficiency varied from 72-88% (results vary with each size).


What concerns me is that the EPA tested 56 stoves but only showed the data for 8 of them. If they worked for me I would have required all the data to be shown too (include manufactures name/model).

 

[shagy]

I do believe all stoves are tested with a full firebox. At least I would think so..That is how anyone would figure out the max btu's. The list of stoves (8) I think on Phase 2 are the only ones that met the OWH 28 method testing. They had to meet the 75% efficiency and be under .31 grams of emissions ?.The phase 1 list met that standard which was less strict.
I am glad to see published data on these furnaces.Should have happened a long time ago. If any out there knows how to get the test results for EKO Tharm Econoburn ect that are published that would be great also. I see Econoburn tested with the method 28 test and didn't do very well. If I remember 50 something efficent. But they still claim 87% with no test data available.I would guess they decided to use a different test. All the inside boilers lack this little bit of info. Why?
I know of a couple people that have the gasification boilers and all are happy with them. Both inside and outside.Both have the had the same problems creosote! A guy with the inside boiler (econoburn) put in a old fuel tank and sprayed foam on it. Now he fires his stove a couple times a day to heat that with only enough wood to last a short time. The other is a E Classic owner that had a 6048 before this one. He was used to packing his old stove to the top and walked away for 36 hrs or so. Which made it smoke like **** Now he puts on only enough to go 12 hrs. He has very little creosote . The wood consumption has dropped about 1/3 to 1/2 from the old stove unlike the story Altheat said. I just spied a other E Classic as driving down the road so I stopped by and ask him questions . He stated he had a rough learning curve with it but after going from his way of thinking to the way the dealer told him to operate the stove it works great.10 face cord on a 3000 sq ft home. Wish it were easier to spot the inside boilers I think what I'm seeing is they all work their best when burning hot and often. In the mean time I have to go stoke my ol Fisher.... Its 10 deg out

 

[heaterman]

"I think what I’m seeing is they all work their best when burning hot and often"

That my friend, is the key to making ANY wood "boiler" efficient and as clean as possible within the capabilities of its design. When that is understood by everyone we will have made some progress. Once that part of the equation gets in peoples minds we can put the whole bit about "dirty wood burners" to bed. Next on the list of things to be driven into wood burning minds would be storage.

 

[TCaldwell]

walks like duck, talks like duck, then must be duck!