Multi-Fuel Boilers

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Product line logo for Multi-Fuel Boilers
BTU/hrBTU/hr Oil or GasTypical Heating Capacity (square ft)Weight (lbs)Flue Size (in)Fuel TypeOptional Backup FuelResidential/ Commercial
WC40150,000N/A1,000 - 4,0001,0508Wood*, Hard Coal, Soft CoalN/AResidential/ Commercial
WOC40150,000225,0001,000 - 4,0001,2308Wood*, Hard Coal, Soft CoalFuel Oil, Propane, NGResidential/ Commercial
WC55225,000N/A2,000 - 5,5001,2208Wood*, Hard Coal, Soft CoalN/AResidential/ Commercial
WOC55225,000225,0002,000 - 5,5001,4008Wood*, Hard Coal, Soft CoalFuel Oil, Propane, NGResidential/ Commercial
WC70265,000N/A3,000 - 7,0001,4508Wood*, Hard Coal, Soft CoalN/AResidential/ Commercial
WOC70265,000250,0003,000-7,0001,6308Wood*, Hard Coal, Soft CoalFuel Oil, Propane, NG, Waste OilResidential/ Commercial
WC100400,000N/A7,000 - 11,0001,9508Wood*, Hard Coal, Soft CoalN/AResidential/ Commercial
WOC100400,000400,0007,000-11,0002,1308Wood*, Hard Coal, Soft CoalFuel Oil, Propane, NG, Waste OilResidential/ Commercial

(Click product image for more detailed specifications)

For the ultimate in fuel-burning flexibility, look to the Multi-fuel boiler. Engineered to burn a variety of fuels with high efficiency, our dual fuel boilers will provide economical heat and hot water for your specific application. This is more than just a dual fuel boiler.

* NOTE:  EPA regulations prohibit continuous firing with wood for residential use, however, they are safe and effective with wood and can burn wood in a commercial application.

Heavy Duty Construction

The Multi-Fuels are made out of ¼ inch Sa-36 steel plate. The Multi-Fuel is a traditional, hand-fired, updraft boiler. They have been sold for more than 40 years now. These units can completely replace your current hot water boiler or can be installed in conjunction with your current boiler.

Cast-Iron Grates

Our grate base design features time-proven perforated cast-iron grates to allow more airflow into the combustion chamber. The grates are linked together to provide even and precise movement for equal ash separation along the entire coal bed, ensuring you have the highest quality ash. The base design is furnished with a larger ash pan with a top handle, making it easier to lift. The ash door design is larger; it will include a gasket for a tight seal and a draft control knob for more precise combustion.

Dual Draft System

Our trademark cast iron grate and our Dual Draft systems allow the burning of various types of solid fuel in the same combustion chamber. Having two different ways to bring air into the fire allows you to customize the airflow to maximize burn efficiency with each kind of fuel.

The Multi-Fuel boilers have a forced draft fan that forces air up through the grates into the fire, perfect for anthracite coal. The other draft option is a natural draft damper. This damper opens and allows the chimney to pull in combustion air. Both of the Draft Systems are controlled by the water temperature.

Water Cooled Baffle

The Multi-Fuel boiler series maximizes each BTU you put in. It has a water-cooled baffle, which increases the amount of time the hot exhaust is in the boiler to extract more heat. The baffle is constructed of schedule 80 2-in diameter pipes. The heavy-duty pipes are water-cooled, which significantly increases the efficiency of the boiler.

Liquid Fuel Backup

The Multi-Fuel boiler is available in configurations that allow you to burn liquid or gas fuel backup. The secret to burning different fuels in the same firebox is a separate firing chamber where fuel oil, natural gas, or propane can be fired.

The difference between our WC and WOC models is that the WOC models have a special burn chamber on the rear of the boiler that allows a burner to be fitted on it. This separate chamber keeps the burner cleaner while you burn solid fuel in the main firebox.  The burner fires into the separate burn chamber, which leads into the main firebox. Whether you are burning oil, hard coal, or soft coal, you only need one flue. The WOC models come standard with a Riello #2 fuel oil burner that is controlled by the boiler’s operate aquastat.


Our Multi-Fuel boilers can be configured to operate without electricity. All you need is some fuel, and you will keep warm. We use a bimetal spring which senses the water temperature and controls the draft accordingly.

Cost of Ownership

Our Multi-Fuel boilers’ cost of ownership is one of the lowest in the industry—$40.00 – $80.00 per year on average!

Burning Wood

Traditionally, Multi-Fuel boilers have been sold as wood/coal combinations; however, due to EPA Phase 2 regulations, these units are no longer sold for residential applications.

For automatic feeding boilers, please explore our Coal Gun product lines

For duel fuel wood gasification boilers, check our Wood Gun.