DF 520 Question.

Stoker Coal Boilers automatically feed the coal and have controls and pumps just like any conventions boiler. They are intended to be used as a primary heat and often have domestic hot water coils as an added bonus. They can be set up independently or in dual sytem with your existing oil/gas boiler. They can accommodate both hot water base board or steam plumbing.
Boots
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Stoker Coal Boiler: Keystoker KA-6
Hand Fed Coal Boiler: Burnham SFB 101 (sold)
Location: Central PA

Post Sun. Jan. 06, 2013 5:21 pm

on EFM' s website it says that u can turn the 520 down to 21,470 btuh. and they claim that is 2.5 lb/hr. what I do not understand is if you have13,000 BTU in a pound of coal that puts the DF 520 somewhere about 65% efficient.

what am I missing here? is the amount of ash in the coal figured in there somehow? Or is it way more complicated, and one can not easily deduce efficiency based on coal input and BTU output?

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lsayre
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Posts: 12187
Joined: Wed. Nov. 23, 2005 9:17 pm
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Blaschak Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW)
Location: N/E Ohio, between Medina and Wadsworth

Post Sun. Jan. 06, 2013 5:24 pm

65% sounds about right by me. Meaning it is in agreement with the overall system efficiency I see with my AHS S130 Coal Gun.
-Larry

Democracy rests upon the principle that collective wisdom arises from a pool of individual ignorance. A Republic rests squarely upon objective law, and fundamentally upon those laws which restrict the scope and actions of government.

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stoker-man
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Joined: Mon. Nov. 19, 2007 9:33 pm
Hand Fed Coal Boiler: 1981 efm wcb-24 in use 365 days a year
Coal Size/Type: Anthracite/Chestnut
Other Heating: Hearthstone wood stove
Location: Lehigh Valley, PA

Post Sun. Jan. 06, 2013 5:31 pm

Coal varies in BTUH depending upon where it is mined. I think it was a very general statement.
‹(•¿•)›

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Rob R.
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Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Coal Size/Type: Lehigh Rice
Other Heating: Dad's 1953 EFM Highboy
Location: Chazy, NY

Post Sun. Jan. 06, 2013 5:33 pm

EFM does not assume the coal will be perfect, and there are other things to consider like efficiency and a pickup factor. The 2.5 lbs per hour of run time per tooth of feed is correct for rice coal. 13,000 BTU's per lb is optimistic...12,000 is more like it. 4 teeth of feed with rice is 10 lbs per hour, allow 80% for the efficiency figure....96,000 btu's/hr.

I have setup three houses in Northern NY with 520's...it is a great boiler that can handle an average home with ease.

What are you looking to heat?

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lsayre
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Posts: 12187
Joined: Wed. Nov. 23, 2005 9:17 pm
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Blaschak Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW)
Location: N/E Ohio, between Medina and Wadsworth

Post Sun. Jan. 06, 2013 5:40 pm

An S130 will throttle down to about 14.5 lbs. per day. I believe the EFM DF520 can also throttle down to well below 60 lbs. per day (which is what 2.5 lbs. per hour of feed would result in over 24 hours). The listed range of 2.5 lbs. to 25 lbs. per hour is most likely for firing feed rates, and they do not account for idling.
-Larry

Democracy rests upon the principle that collective wisdom arises from a pool of individual ignorance. A Republic rests squarely upon objective law, and fundamentally upon those laws which restrict the scope and actions of government.

Boots
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Posts: 196
Joined: Thu. Nov. 10, 2011 4:38 pm
Stoker Coal Boiler: Keystoker KA-6
Hand Fed Coal Boiler: Burnham SFB 101 (sold)
Location: Central PA

Post Sun. Jan. 06, 2013 6:06 pm

Rob R. wrote: What are you looking to heat?
I am heating a 1400 sqft ranch home. single story with full basement. it was built in 1987 so it is fairly well insulated. I use 54 ft. of fin tube baseboard, and there is a cast iron rad. in the basement that measures about 42" x 30" x 8". the oil boiler is rated at 134,000 btuh and my hand fired coal boiler is rated at 85,000'. they both heat the house fine. Also I look to add 2 rooms to the system that are currently not heated, and eventually my 1 car garage.

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lsayre
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Posts: 12187
Joined: Wed. Nov. 23, 2005 9:17 pm
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Blaschak Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW)
Location: N/E Ohio, between Medina and Wadsworth

Post Sun. Jan. 06, 2013 6:11 pm

Boots wrote:
Rob R. wrote: What are you looking to heat?
I am heating a 1400 sqft ranch home. single story with full basement. it was built in 1987 so it is fairly well insulated. I use 54 ft. of fin tube baseboard, and there is a cast iron rad. in the basement that measures about 42" x 30" x 8". the oil boiler is rated at 134,000 btuh and my hand fired coal boiler is rated at 85,000'. they both heat the house fine. Also I look to add 2 rooms to the system that are currently not heated, and eventually my 1 car garage.
With only 54 feet of baseboard you seem to be more in the range of a Keystoker Kaa-2. At 600 BTU's per foot of fin tube baseboard radiator, you may find that you only need 32,500 BTU's of reliable boiler output to max them out. Even the Kaa-2 is more than twice what you need, though it sounds about right if you intend for it to also supply DHW.

An EFM DF520 would potentially heat 6 homes that each require only 54 feet of baseboard radiators.

I have 120 feet of fin tube radiators in my home, plus another roughly 30 feet in my garage, and I think my S130 is oversized for my application. A DF520 would be seriously oversized for my application.
Last edited by lsayre on Sun. Jan. 06, 2013 6:20 pm, edited 1 time in total.
-Larry

Democracy rests upon the principle that collective wisdom arises from a pool of individual ignorance. A Republic rests squarely upon objective law, and fundamentally upon those laws which restrict the scope and actions of government.

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Scottscoaled
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Stoker Coal Boiler: EFM 520, 700, Van Wert 800 GJ 61,53
Baseburners & Antiques: Magic Stewart 16, times 2!
Coal Size/Type: Lots of buck
Other Heating: Slant Fin electric boiler backup
Location: Malta N.Y.

Post Sun. Jan. 06, 2013 6:18 pm

;)
Last edited by Scottscoaled on Sun. Jan. 06, 2013 6:25 pm, edited 1 time in total.
I think a man does what he can, untill his destiny is revealed. Right now that is trying to sell my EFM plate boilers in 520 and 700 sizes.

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Boots
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Posts: 196
Joined: Thu. Nov. 10, 2011 4:38 pm
Stoker Coal Boiler: Keystoker KA-6
Hand Fed Coal Boiler: Burnham SFB 101 (sold)
Location: Central PA

Post Sun. Jan. 06, 2013 6:19 pm

Sorry, I did forget to mention that it will also heat my domestic water

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Rob R.
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Joined: Fri. Dec. 28, 2007 4:26 pm
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Coal Size/Type: Lehigh Rice
Other Heating: Dad's 1953 EFM Highboy
Location: Chazy, NY

Post Sun. Jan. 06, 2013 6:28 pm

Boots wrote:Sorry, I did forget to mention that it will also heat my domestic water
Does that include dual rainforest shower heads and a car wash?

Boots
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Posts: 196
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Stoker Coal Boiler: Keystoker KA-6
Hand Fed Coal Boiler: Burnham SFB 101 (sold)
Location: Central PA

Post Sun. Jan. 06, 2013 6:35 pm

Rob R. wrote:
Boots wrote:Sorry, I did forget to mention that it will also heat my domestic water
Does that include dual rainforest shower heads and a car wash?
afraid not.

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whistlenut
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Stoker Coal Boiler: AA130's,260's, AHS130&260's,EFM900,GJ & V-Wert
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Hot Air Coal Stoker Furnace: Alaska, EFM, Keystoker, Yellow Flame
Hot Air Coal Stoker Stove: Alaska, Keystoker-2,Leisure Line
Hand Fed Coal Stove: Alaska, Gibraltar, Keystone,Vc Vigilant 2
Hand Fed Coal Furnace: Ford, Jensen, NYer, Van Wert,
Baseburners & Antiques: Glenwoods
Coal Size/Type: Barley, Buck, Rice ,Nut, Stove
Other Heating: Oil HWBB
Location: Central NH, Concord area

Post Sun. Jan. 06, 2013 6:46 pm

Boots, you will hear me say this more that once...and I know Rob and Scott will concur: Do NOT UNDERSIZE the boiler.
I know you will expand demand with a garage, workshop, addition...something that you neighbors can't do unless they replace their boilers.
When it is 20 below and there a 5 people taking showers, that small boiler will be like taking a knife to a gunfight! I would NOT risk it.
I have a dozen 260's running year round and they don't overheat. The basements are dry, warm, and comfortable...not a frigging dungeon like most cellars.
SIZE MATTERS!!!! Only people too small to admit it understand this concept.......
"Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a 'piece of human solid waste' by the clean end." More true today....

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lsayre
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Posts: 12187
Joined: Wed. Nov. 23, 2005 9:17 pm
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Blaschak Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW)
Location: N/E Ohio, between Medina and Wadsworth

Post Sun. Jan. 06, 2013 7:40 pm

I agree that once you add two more rooms and a garage along with DHW the idea of the Kaa-2 becomes seriously more iffy, but then again there is actually a guy on this forum who is heating about twice the house you have described, and doing it successfully with only a Kaa-2. He believes them to be under-rated as to their BTU output capabilities. Perhaps he will chime in.
-Larry

Democracy rests upon the principle that collective wisdom arises from a pool of individual ignorance. A Republic rests squarely upon objective law, and fundamentally upon those laws which restrict the scope and actions of government.

User avatar
Rob R.
Site Moderator
Posts: 11343
Joined: Fri. Dec. 28, 2007 4:26 pm
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Coal Size/Type: Lehigh Rice
Other Heating: Dad's 1953 EFM Highboy
Location: Chazy, NY

Post Sun. Jan. 06, 2013 8:24 pm

Boots wrote:
Rob R. wrote: What are you looking to heat?
I am heating a 1400 sqft ranch home. single story with full basement. it was built in 1987 so it is fairly well insulated. I use 54 ft. of fin tube baseboard, and there is a cast iron rad. in the basement that measures about 42" x 30" x 8". the oil boiler is rated at 134,000 btuh and my hand fired coal boiler is rated at 85,000'. they both heat the house fine. Also I look to add 2 rooms to the system that are currently not heated, and eventually my 1 car garage.
Ok, so the heat load is low...what kind of domestic hot water usage is expected? One or two people isn't bad, but throw a few kids into the mix and suddenly the coal boiler is working overtime. My personal opinion is that the "little" boilers like the KAA-2 and LL110 are ok for a light heat & DHW load when there are NO plans to add additional loads. Considering that you are already thinking of adding to the heated space, you should get a boiler with some headroom.

Tightly-sized stoker boilers are fine with everything is going right, but not much fun when you get a load of sub-par coal, or someone forgets a window cracked open on a night with a howling wind.

Boots
Member
Posts: 196
Joined: Thu. Nov. 10, 2011 4:38 pm
Stoker Coal Boiler: Keystoker KA-6
Hand Fed Coal Boiler: Burnham SFB 101 (sold)
Location: Central PA

Post Sun. Jan. 06, 2013 8:54 pm

Rob R. wrote: Ok, so the heat load is low...what kind of domestic hot water usage is expected? One or two people isn't bad, but throw a few kids into the mix and suddenly the coal boiler is working overtime. My personal opinion is that the "little" boilers like the KAA-2 and LL110 are ok for a light heat & DHW load when there are NO plans to add additional loads. Considering that you are already thinking of adding to the heated space, you should get a boiler with some headroom.

Tightly-sized stoker boilers are fine with everything is going right, but not much fun when you get a load of sub-par coal, or someone forgets a window cracked open on a night with a howling wind.
I have a family of four. And in about a year my parents will be staying for extended visits every month or so. There will be lots of showers and laundry.

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