Coal Boilers


The S1000 model offers the highest BTU output of all the Coal Guns —perfect for medium-large commercial buildings. The Coal Gun is nearly 100% automated. You can be confident that your boiler is burning at optimum efficiency, without having to make ongoing adjustments.

Coal Gun boiler units are made to be the last boiler you’ll ever buy, and require only minimal seasonal maintenance. Built for lifetime durability, many of our units are into their fourth decade of operation.

Every AHS Coal Gun is manufactured from the highest quality materials by highly trained, dedicated technicians. Every unit is tested extensively before it leaves our factory to ensure its adherence to our high standards of quality. In fact, we guarantee that our product is free from defects in materials and workmanship*. Each AHS Coal Gun comes complete with all controls necessary for operation and safety. Standard equipment includes an insulated boiler jacket, totally enclosed motor and drive systems, primary and backup aquastat thermostats, thermo ash-monitoring control, pressure relief valve, ash pan (x2) and square hopper with lid. The S1000 also comes with hopper level controls and is ASME certified.

Our Coal Gun boilers are some of the most durable heating units available. The AHS commitment to quality leads to a long boiler life and years of hassle-free operation. The bottom line is that a quality-manufactured AHS Coal Gun will save you both time and money in your heating application.

How It Works…

Pea or buckwheat sized anthracite coal is transferred to the coal pot through the gravity feed hopper. An induced draft fan pulls air through the barrel enhancing combustion of the coal. The hot exhaust gasses then spin through our unique swirl chamber heat exchanger and into the cyclone separator where any fly ash is removed. Anthracite coal does not create creosote or give off any smoke! Though designed primarily for use with hydronic boiler systems, the Coal Gun can be adapted to work with forced hot air systems or steam heating applications.

Fuel Consumption…

The amount of fuel used depends on a great many factors, including the weather, type of installation, and building construction. Due to its high efficiency, however, the AHS Coal Gun uses less fuel than other units on the market and will substantially reduce your annual heating costs.

Thermo Ash-Monitoring Control…

All Coal Gun® boilers feature a Thermo Ash-Monitoring Control which provides optimal use of your fuel. Ash that contains fuel that is not fully combusted will be a higher temperature than ash coming from thoroughly combusted fuel. The Thermo Ash-Monitoring Control automatically monitors the temperature of the ash leaving the coal pot and leaves the ash in place until complete combustion occurs before allowing it to fall away. No adjustment from the factory setting is typically necessary to have the boiler perform at peak power output throughout the burn season (a minor on-site adjustment may be necessary when the boiler is first installed). With the Thermo Ash-Monitoring controlled grate, it is possible for the fire to remain lit for days during low use periods.

*Limited Warranty

Alternate Heating Systems boilers and furnaces are warranted against defects in materials and workmanship for the following periods:

  • Boiler Vessel – 20 years pro-rated
  • Grate S130/S260 -Lifetime
  • Grate S500/S1000 – 12-months
  • All other components both manufactured by Alternate
    Heating Systems and purchased from vendors will
    vary in length of warranty from 30 days to 1 year

A copy of the complete warranty text, detailing coverage, limitations, warranty claim procedure and state law rights is available from Alternate Heating Systems.

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  • Simple to Use
  • Smoke Free
  • Minimal Maintenance
  • Cost Effective
  • Fuel Efficient
  • Versatile Applications
  • Lifetime Durability
  • Standard ASME Certification

Call (717) 987-0099 for pricing

Assembled Specifications



Heating Capacity (max sqft)


Approximate Water Capacity (gal)


Width (in)


Height (top of hopper) (in)


Length (in)


Approximate Weight (lbs)


Flue Size (in)


Return Tapping (NPT) (in)

(2) 2 1/2

Supply Tapping (NPT) (in)

(2) 2 1/2

Hopper Capacity (lbs)



Extended Base

The Extended Base upgrade for the S1000 gives it an extra-large ash pan that is 3x bigger than the standard ash pan, which greatly extends the time period between emptying. It also makes the ash pan accessible to front-end loaders making dumping the ash hands-free


Domestic Coil

This Domestic Coil features a 100° F rise at 5 gallons per minute, 50° water inlet temperature and 65 PSI water pressure. It is threaded into a 4 IN NPT threaded fitting provided on the boiler for this purpose.


Warnock Hersey Certification

WH certification is available on all Coal Gun boilers for an additional charge. This certification assures that the boiler complies to UL 2523 Standards. Some insurance companies may require this certification and it is the responsibility of the homeowner to determine the need for a WH certification on any boiler purchased.

Auger Loading

The Coal Gun can be enhanced with an auger add-on that eliminates the need to manually fill the hopper. This is especially important on the large models (S500, S1000), as a higher demand for heat requires more regular filling. Auger add-ons have both automatic and manual settings for maintaining coal reserves.

4″ or 6″ Diameter

Your choice of diameter will depend on load size and cleanliness of coal. If your coal typically has debris, like wood chunks, a 6″ auger would be recommended. Auger length can be customized per requirements.

Auger Inlet Guard

An auger inlet guard provides added safety. The guard’s sturdy mesh screen prevents unwanted objects from contacting the auger screw.

Low Water Cutoff

A Low Water Cutoff senses the water level in the boiler’s vessel and will shut the unit down if the water level drops to an unsafe level. Available with automatic reset or manual reset.