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 PORTAGE & MAIN PRODUCTS - Ultimate Outdoor Furnace, LLC

More Innovation and Expertise for Your Alternative Heating Needs


Ultimate Outdoor Furnace offers customers the Portage & Main Boilers that have been manufactured for over 40 years as leading innovators in the outdoor boiler business. The research and recognition of these boilers add the value with a clean-burning, an environmentally friendly boiler that will save them fuel, money and time.

The Portage & Main products offered by ultimate Outdoor Furnace range of products include Ultimizer wood and coal models, auto-feed coal/pellet burners, automated wood chip burning systems and a line of EPA approved gasification boilers. 

These time tested and proven designs offer some of the most efficient heat transfer exchangers available in any outdoor boiler on the market today.

Portage and Main Boiler customers are homeowners, farmers, commercial and industrial businesses, schools and municipal authorities. We sell boilers across the entire continental US.


Our STANDARD Heater delivers on simplicity. Nothing is complicated about this heater. Get wood... any kind or type of wood. If it isn't dry wood, let it dry for a few months.


Gasification Furnaces Products are extremely clean burning outdoor wood furnaces with emissions as low as 1.96 grams per hour and efficiency over 86%.


Our various series are also available and use wood, coal, .

The Ultimizer Wood Series
The Ultimizer uses a revolutionary design to eliminate the problems associated (until now) with outdoor boilers. ie. smoke, creosote, moisture, corrosion
EGR  Gassification Series
The EGR Optimzer Wood Gasification model burns all types of seasoned dry wood - achieves even more savings for you.
Portage & Main Other Units
Keep your energy dollars circulating in your local economy and support jobs in your local forest products industry.
Ultimizer Wood/Coal Series
The Ultimizer Wood Series


The Ultimizer wood series is the product of more than 40 years of research and development that has earned Portage & Main Outdoor Boilers the reputation as an industry leader. 

With four sizes available, heating from under 2,000 sq ft to 12,000 sq ft, producing up to 500,000 BTUs. The Ultimizer can be connected to virtually any existing forced air or hydronic radiant heating system. Heat your home, domestic hot water, other buildings, hot tub, swimming pool, and more.

The Coal Series


The Ultimizer coal shaker grate model - the original shaker grate.


This model is unsurpassed in efficiency, reliability, and long lasting durability. Save time, labor and thousands of dollars in fuel over the years. Both the Ultimizer shaker grate coal and wood burning models share many of the same quality features, such as the all important refractory cement lining which retains heat and encourages proper combustion.

With water temperatures going from 50 to 180 degrees in less than one hour - that’s the fastest recovery time in the industry!

Optimizer 250
EGR Optimizer Wood Gasification


Not just a pretty face, this boiler is a heavy weight and is packed with energy saving features. The EGR Optimizer burns all types of seasoned wood. This gasification boiler is built with some of the same principals as commercial industrial boilers – dry based, sectional design, efficient multi-pass fire tube heat exchanger. 

When you purchase an EGR Optimizer Wood Gasification model, you will burn a lot less wood and get more heat and comfort. You will enjoy a consistent burn that will heat your home, garage and barn all at the same time. Keep the mess and the danger out of your home - all this warmth while enjoying a quick return on your investment.

What It Means For The Environment

The reports of dwindling fossil fuel supplies and a growing concern for the environment have governments and individuals alike looking for alternative heating options.
Portage and Main is proud to introduce the EGR gasification series which addresses the demand for a high efficiency, low emission furnace.

  • Not just a pretty face, the Optimizer EGR gasification model is a true heavy weight.

  • Built with some of the same principals as commercial industrial boilers – dry base, sectional design, efficient multi-pass heat exchanger.

  • Packed with energy saving features.

  • A consistent burn that heats your home and multiple buildings all at the same time.

  • Highly efficient – use less wood to give more heat.

  • Enjoy a quick return on your investment.

Portage & Main's most efficient design of heat exchanger


The Portage & Main EGR has not just one, but two high efficiency flue tube heat exchangers. This makes our brand one of the most efficient, most modern gasification units on the market today. Time tested and proven – this type of flue tube heat exchanger was the most efficient design 150 years ago and  is still the most efficient design today.

Optimal heat extraction saves the work and cost involved in burning wood.

Multi Fuel 
The Stoker Series


This multi-fuel boiler gives you the option to burn either coal or pellets. It will burtn 1/3 to 1/2 less fuel than any other conventional outdoor boilers. The auger feed bin system provides the convenience of having an efficient outdoor boiler that operates for extended periods of time without user input. Virtually smokeless, the Stoker series will heat 10,000 sq ft to 30,000 sq ft.


The Stoker series burns coal, wood pellets, oat hulls, grass pellets, sunflower hulls, cherry pips – basically any biomass that will flow from a storage bin - it even removes its own ashes. 

The Envirochip Series


Heating with Biomass made easy.

Portage & Main Chip Burning Hydronic Boilers give a longer burn time between fills and use less fuel than conventional wood boilers. The automated features eliminate daily service and provide heat for residential homes, garages, shops, businesses, farms, green houses, municipal buildings, apartments, resorts, retirement homes, kilns, domestic hot water, swimming pools, hot tubs and more.


The B500 makes burning biomass attractive and affordable for both residential and commercial properties.

The Envirochip Benefits


  • No fire hazard in your building;

  • Virtually no smoke;

  • The water temperature is electronically controlled with an aquastat.

The LCB 120K Envirochip Series


An EASY to use, Highly Efficient wood chip/pellet burner for residential market. 

The LCB-120 burner is a fully enclosed unit comprising of three parts:

Portage & Main Boiler - The burning unit has a high efficiency, 3-pass fire tube heat exchanger. Rock the turbulators with a handle to make quick work of cleaning the heat exchanger. The LCB-120 utlilizes and automated step floor that moves, ensureing that the burner grates are kept clean. Controls turn the feed system and combustion air on and off according to the water temperature. 

Automatic Stoker - Time tested and reliable. Heavy duty 4" diameter auger feed system.  Industrial quality Bonfiglioli gear box drive. Heavy duty Leeson drive motor ( 3-phase, inverted for residential use) 

Chip Storage Bin- Fill the 3.5 cubic yard storage bin using a utility tractor or loader. Enjoy constant, controllable heat for five to seven days* between fills.

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