Boiler Mate

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.
Posts: 2732
Joined: Tue. Sep. 04, 2007 10:14 pm
Stoker Coal Boiler: H.B. Smith 350 Mills boiler/EFM 85R stoker
Coal Size/Type: Buckwheat/anthracite
Location: Dalton, MA

Post Tue. Aug. 20, 2013 2:49 pm

I don't want to mess with Rob, but I'll still vote for the 7 gpm coil. It is a few more $ up front, but I think its larger surface area would let you produce any given DHW flow rate with a lower boiler water temperature, so you'd save on standby losses. And it provides extra capacity in case you want to run the dishwasher or laundry, have people take showers, or carry whatever other DHW loads you have. Plus, it was the original equipment spec'd by EFM for 700's, and is called for under the Massive Overkill Doctrine to which I subscribe. :lol:


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Rob R.
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Posts: 11347
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 Tue. Aug. 20, 2013 3:48 pm

I was trying to be cost sensitive. If the funds are available, use the 7 gpm coil. If even more funds are available, look at an indirect.

This boiler is in a remote building, so I assumed there would not be additional DHW load during the pressure washing.

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Posts: 2597
Joined: Tue. Jan. 08, 2008 9:51 pm
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 Tue. Aug. 20, 2013 5:58 pm

Boiler is in attached mother of all god garage.
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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Mark (PA)
Posts: 383
Joined: Thu. Feb. 28, 2008 9:40 am
Stove/Furnace Make: 1953 EFM SF-520 High Boy
Stove/Furnace Model: Fitzgibbon Boiler
Location: South Central, PA

Post Wed. Aug. 21, 2013 9:29 pm

I like my 7 GPM coil... ;) while your doing it....

Phil May
Posts: 194
Joined: Sun. Nov. 06, 2011 9:12 pm
Stoker Coal Boiler: EFM 700
Coal Size/Type: Buckwheat
Stove/Furnace Make: EFM
Stove/Furnace Model: 700
Location: Wellsville NY

Post Thu. Aug. 22, 2013 4:39 pm

Yes the water is hard but it has not been a problem with my appliances and we built the house in 1997. I am going to try the coil. I am going to mix the water at the spicket. I am going to use 3/4 in and out for the coil.

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Posts: 12204
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 Thu. Aug. 22, 2013 6:02 pm

I would add a proper mixing valve so you don't get scalded. There are several good brands. This is the one I have: ... xing-Valve

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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Posts: 282
Joined: Fri. Jun. 20, 2008 9:27 am
Stoker Coal Boiler: EFM DF520
Coal Size/Type: Rice
Stove/Furnace Make: EMF
Stove/Furnace Model: DF-520

Post Wed. Sep. 18, 2013 7:02 pm

I ran the hot water from the DF520 7gpm coil to a Marathon 85 gallon hot water heater as a big capacitor. Works great even with the Marathon heating element off. My wife says this is the best space capsule I have ever bought since it keeps her soaking tub filled with hot water. No more angry faces or threats to replace my DF520 boiler(or was that me?)! Coal just takes too long to heat up to keep up with lots of domestic hot water. When its on oil its fine, but not on coal. Takes a while to get the coal nice and hot!


Posts: 2732
Joined: Tue. Sep. 04, 2007 10:14 pm
Stoker Coal Boiler: H.B. Smith 350 Mills boiler/EFM 85R stoker
Coal Size/Type: Buckwheat/anthracite
Location: Dalton, MA

Post Wed. Sep. 18, 2013 7:47 pm

To handle big DHW loads with a coil you need to make sure the feed/air rates and low temp limits are set accordingly. In our old house we used a coil in an EFM 900 and it made infinite hot water for a family of 8 without breaking a sweat.


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