Commercial Wood Boilers


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The E250 is part of the Wood Gun family of wood gasification boilers It puts out 250,000btu/hr and will heat up to 9,000 square feet. As with all our commercial wood boilers, we can equip the E250 to automatically feed various types of wood fuel, like pellets, chips, sawdust, or shavings, into the firebox.

You can use our wood boilers  in any heating applications (water-based, steam, forced-air). The Wood Gun™ series has been tried and true for over 35 years! Our wood gasification boilers reduce the amount of labor that you typically associate with a wood boiler.

The Wood Gun™ wood gasification boiler by Alternate Heating Systems is perhaps the most efficient wood-burning device on the market today. These wood boilers are an uncompromising multifuel system if you use conventional log wood as fuel in any commercial heating application. The E250 wood boiler can heat homes up to 9,000 square feet, subject to building design and construction.

Wood Characteristics

The firebox of each Wood Gun™ can accommodate wood sizes ranging from unsplit logs to complete rounds up to 10″. Typically, you need only to load the large firebox  2-3 times daily. Our commercial wood boilers handle wood of relatively high moisture content, as high as 35% moisture, this frees you from curing a 12–18-month supply of firewood (30% moisture or less is preferred). Unlike European-style gasifiers, the Wood Gun excels on full rounds.


Weekly cleaning of our wood gasification boilers will, of course, give you the best performance. The easy-access front and rear inspection doors and included ash scoop and rake make cleaning fast and convenient.

A high-velocity draft fan moves air through the wood allowing for an easy cold startup. After the gasification process begins, this air movement produces intense flames and very high temperatures in the gasification tunnel. In turn, the air flows through the heat exchanger, cleaning it as it passes through.

Back-up Options

You can upgrade your Wood Gun™ boiler with either fuel oil, natural gas, or LP gas backup. The Riello fuel oil burner will allow you the option of automatic backup. Combining your burner with your commercial wood boiler will enable you to save money by burning a renewable fuel source and the convenience of burning oil. The oil backup system is rated over 84% efficient. You cannot go wrong with an efficiency rating that rivals top-of-the-line oil units.

Stainless Steel Construction

Wood Gun™ boilers use ¼” thick Type 304 stainless steel in the construction of the firebox, heat exchanger, and door frames. We use Type 304 stainless steel in our wood boilers for its unsurpassed quality and longevity. Our stainless-steel wood boilers, even after over 35 years of service, show no deterioration. However, the Wood Gun models are available in both carbon steel and stainless steel.


The Wood Gun™ wood gasification boiler, when installed, maintained, and operated properly, produces no visible smoke, and prevents creosote formation in the chimney.

Stack Temperature

Exhaust stack temperature is one indicator of transfer efficiency. The secondary combustion chamber reaches temperatures of nearly 2000° Fahrenheit (which consequently burns the smoke and creosote). Amazingly, our exhaust stack temperature ranges from about 260-300° Fahrenheit. This stack temperature is unheard of in the industry. The Alternate Heating Systems Wood Gun™ is the pinnacle of wood-fueled heating devices!

How it works

In order to burn smoke-free in a wood boiler. You have to force the gas out of the wood by applying high heat to the wood, which is the process of pyrolysis. Our commercial wood gasification boilers draw wood gas through the bottom of the firebox and into our uniquely designed refractory by an induction fan. The gases combine with oxygen and combust in the refractory. The super-heated gases pass through the interconnected refractory tunnels and into our uniquely designed swirl chamber. This is where the bulk of heat exchange takes place. Above the heat exchanger, the super-heated refractory continues to gasify the wood remaining in the firebox. After combustion, the residual ash is combined with high-velocity airflow to scrub the heat exchanger preventing any build-up. This process leads to unparalleled consistency in heat exchange. The cyclone ash separator collects most of the ash after it leaves the heat exchanger for fast and easy removal.

The Wood Gun™ will cycle on and off like an oil or gas-fired boiler. During the off-cycle, the boiler does not consume the wood because oxygen is not present in the combustion chamber. With the large super-heated refractory mass, re-ignition of the wood occurs automatically when a drop in water temperature signals the need for heat. Automatic re-ignition can take as long as 4 hours after the last firing cycle, depending on the size of the wood boiler.

During the off-cycle, wood gas inside the firebox condenses on the inner walls forming creosote that will eventually fall off. Once the creosote falls off, it combines with the remaining fuel, adding energy that in many other boilers goes up the chimney.

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  • Fuel Efficient
  • Minimal Maintenance
  • Lifetime Durability
  • Versatile Applications
  • Wood Gasification
  • 304 Stainless Steel
  • Made in Pa

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Assembled Specifications



Typical Heating Capacity (square ft)


Standard Door Opening (in)


Firebox Capacity (cubic ft)


Firebox Length (in)


Approximate Water Capacity (gal)


Width (cyclone removed) (in)


Height (in)


Depth (in)


Flue Size (in)


Weight (without gas/oil backup) (lbs)



Smoke Exhaust Hood

The Smoke Exhaust Hood mounts over the load door, capturing any smoke that may escape during the fuel-loading process. This smoke is then vented directly to the outside through a separate vent. When tolerance for smoke is low, the smoke exhaust hood is essential.


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.

Can be equipped with multiple coils as needed.

Low Temperature Shutdown

If all the fuel has been consumed in your boiler, the Low Temperature Shutdown Feature prevents the boiler from attempting to fire. This keeps the draft fan from blowing the remaining heat out through the flue.

Cycle Timer

This feature adds a timer that triggers the boiler to run for 10 minutes every 2 hours, even if there is no call for heat. This maintains an internal temperature above the kindling point, reducing the need to manually relight the unit during periods of low demand.

Automatic Feed

The Wood Gun™ series can be ordered with the ability to automatically feed itself wood particle fuels, such as sawdust, wood chips, shaving, pellets, etc. The Wood Gun™ auto-feed system loads the fuel into the firebox from the top. Only slight reconfiguration is required to still burn logwood in the firebox! This option comes with a photo-eye sensor, which controls when more fuel is needed, and an upgraded control center, which allows the user to easily control the entire system in one location. Touchscreen controls are available as well.

Additional Required Pieces:
  • Rotary Airlock – Rubber blades or machined stainless steel.
  • Fuel-Valve – acts as a second airlock, available in stainless steel.
  • Transition Tubes – available in stainless steel – connects the boiler to Airlock, Fuel-Valve, and Auger
  • Auger – available in nearly any diameter (4″, 6″, 8″, 10″) and any length
  • Diverter Bricks
  • Secondary Air Brick with cover

Variable Speed Induction Fan

This enables the BTU output to be easily changed. This is accomplished by upgrading the 1-phase motor to a 3-phase motor and controlling the motor with a Variable Frequency Drive.

Oil/Propane/Natural Gas Backup

The Wood Gun wood boiler can be fitted with a backup fuel option. This requires a dedicated firing tube that must be built in during manufacturing.

The E250 is capable of producing 230,000 BTU/hr when burning oil, propane, or natural gas.

Automatic/Manual Switching

For #2 fuel oil, the oil backup can function in an automatic switch-over scenario, with fuel oil taking over when the boiler has exhausted its wood fuel. For other fuels, such as natural gas or propane, switch-over is manual only.

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.

ASME Certification

The ASME Certification guarantees the steel grade and weld quality of the boiler water jacket. Each ASME Certified water jacket has been pressure tested to 60 PSI, and includes a 30 PSI release valve.

Low Pressure Steam

The Honeywell Aquastasts are switched out for Honeywell PressureTrolls and two Low Water Cutoffs are included. An automatic water fill valve and Steam Relief-Valve are also included. In some models, the vessel is changed slightly to allow for a larger steam shelf. The Wood Gun can produce steam up to 15 psi. To know what size steam boiler you need, first, figure the amount of BTU/hr needed for your home, then add 20% to the total. This extra 20% is only needed to create the initial head of steam.

Note: only available on Carbon Steel boilers.

Canister Pool Heater

Heat your pool with wood! Available in either Carbon Steel or Stainless Steel. This is a separate canister from the vessel.

Custom Engineering

At Alternate Heating Systems we have expert fabricators and engineers ready to tackle any design change! Whether it’s a custom bin, moving the cyclone to the other side, an extra load door, water storage tank, or whatever you may need to fit your application.