diff. between EFM 520 and DF 520?

What is the difference beetween a EFM 520 and a EFM DF 520 if there is any at all? Thanks for any input.
-Luke

The DF stands for dual fuel w/ oil burner, ??? if their any other differences

The "plain vanilla" EFM 520 boiler only has the coal stoker; while, the EFM DF-520 has the coal stoker as the primary heat source plus a backup oil burner for a backup/secondary heat source. I'm sure one of the EFM experts will weigh in on this subject; perhaps, they can provide details on how the DF-520 is switched between coal and oil.

Wow fast reply. Thank you all for the info. DF = Duel Fuel. Sound logical to me.

DF's don't necessarily have an oil burner installed, only provisions in the left side of the boiler. Use the search box on the upper right and you will find out more than you ever wanted to know about 350's. 520's DF 520's, 700's, 900's and an occasional 1300.

Thanks Whistlenut. I will do the search. In the meantime: Is the 350 the smallest? Vs. the 520?

The 350 is the "baby".

Luke D wrote:Thanks Whistlenut. I will do the search. In the meantime: Is the 350 the smallest? Vs. the 520?

AP 350 holds 29 to 31 gals of water depending who the manufacture was and if it is a Sq top or Round Top
AP 520-1 520 holds 40 To 41 gals of water depending who the Manufacturer was and Tube boiler Vs Flat Plate heat exchanger boiler. Stokers are the same .

AP 350 Base size 24 1/8 " wide 32 1/2" Long 24 1/8" tall. With Jackets on 27 5/8" wide 38 1/8 Long 51 3/8" Tall
Boiler top 23 5/8" Wide 32 1/2" long 27 3/4" Tall. Heating Surface Sq Ft 22.5
Boiler weight is 575 lbs base is 135 lbs stoker is 214 lbs Jackets 105 lbs total weight 1029 lbs .

AP 520 -1 Base size 26 1/8" wide 36 1/2 Long 24 1/8" Tall
Boiler top 25 1/4" Wide 36 7/8" Long 28 3/8" Tall . Heating Surface SQ Ft 28.3
Boiler weight 750 lbs Base 142 Lbs Stoker 214 lbs Jackets 109 lbs Total weight 1215 lbs

DF 520 same size as AP-520-1 except weigh total weight 1250 shipping weight on DF 520

Note that about the same time the 520 became "Duel Fuel" capable, the viewing door was changed from a round door to a much larger square door.

markviii wrote:Note that about the same time the 520 became "Duel Fuel" capable, the viewing door was changed from a round door to a much larger square door.

No in 1978 The DF came out Round door up until late 1980 to early 1981 I seen both 1980 & 1981 Still having Round doors
One of My good friends has a Kirkland made boiler top 1981 round door Non DF model EFM did some weird stuff over the years .

coal berner wrote:

Luke D wrote:Thanks Whistlenut. I will do the search. In the meantime: Is the 350 the smallest? Vs. the 520?

AP 350 holds 29 to 31 gals of water depending who the manufacture was and if it is a Sq top or Round Top
AP 520-1 520 holds 40 To 41 gals of water depending who the Manufacturer was and Tube boiler Vs Flat Plate heat exchanger boiler. Stokers are the same .

AP 350 Base size 24 1/8 " wide 32 1/2" Long 24 1/8" tall. With Jackets on 27 5/8" wide 38 1/8 Long 51 3/8" Tall
Boiler top 23 5/8" Wide 32 1/2" long 27 3/4" Tall. Heating Surface Sq Ft 22.5
Boiler weight is 575 lbs base is 135 lbs stoker is 214 lbs Jackets 105 lbs total weight 1029 lbs .

AP 520 -1 Base size 26 1/8" wide 36 1/2 Long 24 1/8" Tall
Boiler top 25 1/4" Wide 36 7/8" Long 28 3/8" Tall . Heating Surface SQ Ft 28.3
Boiler weight 750 lbs Base 142 Lbs Stoker 214 lbs Jackets 109 lbs Total weight 1215 lbs

DF 520 same size as AP-520-1 except weigh total weight 1250 shipping weight on DF 520

Thanks for the info coal berner. Your like an EFM encyclopedia

coal berner wrote:

markviii wrote:Note that about the same time the 520 became "Duel Fuel" capable, the viewing door was changed from a round door to a much larger square door.

No in 1978 The DF came out Round door up until late 1980 to early 1981 I seen both 1980 & 1981 Still having Round doors
One of My good friends has a Kirkland made boiler top 1981 round door Non DF model EFM did some weird stuff over the years .

That is why I underlined "about"...because it was not a clear cut transition. Thanks for the clarification on the years.

-Rob

markviii wrote:

coal berner wrote:

markviii wrote:Note that about the same time the 520 became "Duel Fuel" capable, the viewing door was changed from a round door to a much larger square door.

No in 1978 The DF came out Round door up until late 1980 to early 1981 I seen both 1980 & 1981 Still having Round doors
One of My good friends has a Kirkland made boiler top 1981 round door Non DF model EFM did some weird stuff over the years .

That is why I underlined "about"...because it was not a clear cut transition. Thanks for the clarification on the years.

-Rob

Yea that's ok efm is not even clear on trasition