Stoker Rating Accurate?

Post Reply
 
Paulie
Member
Posts: 834
Joined: Tue. Apr. 08, 2008 8:44 pm
Location: MA, South Shore

Post by Paulie » Thu. Mar. 19, 2009 1:13 pm

Just wondering if anyone ever checked the BTU Ratings on your stove. Checking weights of coal used, burning a full grate,
breaking down the BTU to pound, and doing the math, I am not coming close to the rating of the stove. So, my math is junk,
or the BTU value of my coal is enormous or the stove is rated higher than its capacity, or , the testing method is not close to
real world. Anybody else ever check? Even allowing 10% error , I am still not close.


 
User avatar
LsFarm
Member
Posts: 7383
Joined: Sun. Nov. 20, 2005 8:02 pm
Location: Michigan
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Post by LsFarm » Thu. Mar. 19, 2009 2:41 pm

Some stoves are rated by BTU input [max coal feed and burn rate] and some are rated by BTU output, which factors in the efficiency of the steel box at getting the heat out of the fire and into the room.

Explain how you are doing the math, and also, do you use a barometric damper?? If not, a good 30-40% of your heat can just go up the chimney if you have a strong draft.

Greg L

 
Paulie
Member
Posts: 834
Joined: Tue. Apr. 08, 2008 8:44 pm
Location: MA, South Shore

Post by Paulie » Thu. Mar. 19, 2009 3:59 pm

I am using input #s as it is the only way I have,lacking instruments. My stove ,as most, is rated on input. Base numbers 26000000 BTU per ton divide by the stove rating 90000btu/hr.
This gives me 289.(288.8) hours at 90000/BTU .. Measuring FULL BURN is tricky as it is a guess. But figuring a full grate
burning all the time, which I have because my stove is undersized, . 289 divided by 24 = 12.041 days So, I should be burning
1 ton every 12.041 days. Well, I am not even close. I realize my BTU input is a guess, but it is a pretty good one, so it should
be in the ball park, it is not. I am burning 65-70 pounds a day. 26000000. divided by 2000 equals 13000BTU/lb. Burning
65LBS per 24 hrs equals 845000/BTU equals 1 Ton every 30 something days. Even at 70lbs, every 28ish days. These are close
based on my non NASA caliber consumption measurements. Sooooooo, why the is the theoretical burn rate more than
double the actual? Even allowing a large margin of error, it should be close. My math may be junk by missing something
obvious or just mixing my "apples and oranges" incorrectly. Stove is rated for 90000BTU/HR, so a full grate should be "close"
to 90000/BTU-HR. I realize that my measurements leave some wiggle room,but 50% wiggle?
As far as the stove and baro, set up, no problems. Throws big heat 24/7. Keeps the oil to a min in my big old house.
So, could not be happier( well, maybe if my boiler would show up.....). I am just curious why my theoretical numbers are
not even close to actual. Where am I dropping the ball? Am I ? If I am not, my stove is not rated close or my coal is
packing one hell of a punch.

 
User avatar
coaledsweat
Site Moderator
Posts: 13763
Joined: Fri. Oct. 27, 2006 2:05 pm
Location: Guilford, Connecticut
Stoker Coal Boiler: Axeman Anderson 260M
Coal Size/Type: Pea

Post by coaledsweat » Fri. Mar. 20, 2009 9:18 am

70# a day = 910,000 BTUs. Divided by 24 hours equals 37,917 input BTUs, @ 70% efficiency your stoves output is around 26,542 BTUs per hour at that rate. If you burn 166# per day you are at the maximum rating of 90,000 BTUs (90,000/13,000 = 6.923 X 24 = 166#. Output would be around 63,000 BTUs.

Don't be bashful, open some windows and doors and go WOT. :)

 
User avatar
LsFarm
Member
Posts: 7383
Joined: Sun. Nov. 20, 2005 8:02 pm
Location: Michigan
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Post by LsFarm » Fri. Mar. 20, 2009 6:39 pm

Is the grate fully covered with burning coal,, with only a half inch of ash at the end,, with the ocassional red piece of coal dropping into the ash pan?

Where is your coal from? some coal is hotter than others..

Greg L

 
Paulie
Member
Posts: 834
Joined: Tue. Apr. 08, 2008 8:44 pm
Location: MA, South Shore

Post by Paulie » Fri. Mar. 20, 2009 8:55 pm

Full burning grate, coal is Kimmels rice, meadow brook mine. Crunching the math, I keep getting 54000 BTU/hr input rate.
Adjusting the lbs of coal burned 10% to compensate for my shaky measurement, still leaves me with a HUGE difference
between stove rating and consumption/actual. Ah well, it is all academic, as I am warm as toast. :D

 
User avatar
BigBarney
Member
Posts: 1853
Joined: Wed. Feb. 08, 2006 2:48 pm

Post by BigBarney » Mon. Mar. 30, 2009 3:20 pm

Generally solid fuel heaters are rated by input BTU because of the variation in the fuel and

other factors.Nat gas and oil have set BTU's per unit measure so are rated at input and output

for each appliance.

Since Anthracite coal has ~12500 btu/# of clean coal with no ash,water,or gases,you have

to take these out of the equation.A 14% ash coal with 2% water has about 10500 BTU's of

usable heat per pound.If your stoker burn 99% of the available coal,and it burns 10# /hr

you got 103950 BTU's of heat energy.The more complicated calculation is how much heat you

actually transferred to the house,these are beyond what most can measure without many

instruments.You have to take off chimney loss,room air burned,density of air,oxygen content,

and many other variables.

BigBarney


 
Paulie
Member
Posts: 834
Joined: Tue. Apr. 08, 2008 8:44 pm
Location: MA, South Shore

Post by Paulie » Mon. Mar. 30, 2009 7:21 pm

I understand the variables, but even so, the rated input of the stove is WAY higher than what I can actually get in it.
And that is figuring 12500BTU/lb. Going to 10500BTU/lb the spread is even farther. So, how do they rate the input,
unless they are using super soft coal that is putting out some huge heat quick, I can not get close. I can see being off
even 25-30 pts. But I am consistently 45% off at 12500btu/lb. Using a lower BTU value, the spread between rated input
and actual grows to 60%. With sketchy measure, allowing for large variable in lbs burned, BTU values, I am still not even close
any way I calculate it. I would think I could get with in 20% allowing for a spread on the lbs burnt/btu values. I am not even
close.

 
bustedwing
Member
Posts: 152
Joined: Sun. May. 11, 2008 1:48 pm
Location: south central pa
Hot Air Coal Stoker Furnace: LL Pioneer
Coal Size/Type: Rice
Other Heating: Hot air oil

Post by bustedwing » Sat. Apr. 04, 2009 2:16 pm

Hmm..,interesting question.Jerry at LL should have the answer.My Pioneer has used 11,000 lbs since sept. 17,that's 199 burning days =55.2 lbs/coal per day average,605k btu/day (wet coal with about 30% buck and a little pea in the load)or average of 25,200 btu/hour.Really cold days was closer to 100 lbs/day,days like today maybe only 1 bucket(28 lbs).Also used 1/4 tank of oil(275gal tank).Guess I really don't give a hoot what the theoretical max is as it did the job just fine in a long colder than usual winter.Old uninsulated house too.Don't let the numbers drive you buggy. RichB

 
bustedwing
Member
Posts: 152
Joined: Sun. May. 11, 2008 1:48 pm
Location: south central pa
Hot Air Coal Stoker Furnace: LL Pioneer
Coal Size/Type: Rice
Other Heating: Hot air oil

Post by bustedwing » Sat. Apr. 04, 2009 2:19 pm

OOPs,forgot,I used 11,000 btu/pound guestimate because it's wet and not all rice. RichB

 
Paulie
Member
Posts: 834
Joined: Tue. Apr. 08, 2008 8:44 pm
Location: MA, South Shore

Post by Paulie » Sat. Apr. 04, 2009 11:00 pm

I dumped the number puzzle.I was curious about the numbers and why I could not come close. Bottom line is what I have worked good, and now I want MORE. Still waiting on a boiler. If I do not see it
by summer, I will get a larger stove with a custom monster hot water coil to help the oil boiler. My house is old, updated, but
still old. More heat is good! :up:

 
valley coal
New Member
Posts: 12
Joined: Tue. Feb. 10, 2009 7:31 pm

Post by valley coal » Sun. Apr. 05, 2009 2:42 pm

What brand of boiler was that Paulie?

 
Paulie
Member
Posts: 834
Joined: Tue. Apr. 08, 2008 8:44 pm
Location: MA, South Shore

Post by Paulie » Sun. Apr. 05, 2009 11:32 pm

Waiting on a Keystoker, been 10 months and counting. I am hoping by summer, if not I will go with plan B.

 
User avatar
oliver power
Member
Posts: 2970
Joined: Sun. Apr. 16, 2006 9:28 am
Location: Near Dansville, NY
Stoker Coal Boiler: KEYSTOKER Kaa-2
Hand Fed Coal Stove: Hitzer 50-93 & 30-95, Vigilant (pre-2310), D.S. 1600 Circulator, Hitzer 254

Post by oliver power » Tue. Apr. 07, 2009 10:01 pm

What size keystoker are you buying Paulie? Just currious.

 
Paulie
Member
Posts: 834
Joined: Tue. Apr. 08, 2008 8:44 pm
Location: MA, South Shore

Post by Paulie » Tue. Apr. 07, 2009 11:06 pm

KA-6, I hope! I call the dealer every two weeks, he in turn calls Keystoker. Last call was at the end of March, I will wait until May 1 to call. I am going to a 4 week call rotation for the spring/summer. I would hope that I would have it by June, from
what I understand, they are still slammed. Even with canceled orders, they have a ways to go to catch up. Not a bad problem
to have as a manufacturer, crappy if you are the customer.


Post Reply

Return to “Stoker Coal Furnaces & Stoves Using Anthracite (Hot Air)”