How We Optimize the Air to Fuel Ratio in Outdoor Boilers

How We Optimize the Air to Fuel Ratio in Outdoor Boilers

Transforming wood, coal, or biomass to gas may seem like a magic trick but it isn’t. It is simple science. In outdoor boilers, combustion is “staged” through a series of processes that allow the fuel to be burned extremely efficiently. By almost completely burning the fuel, outdoor gasification furnaces lower emissions and reduce fuel consumption.

The Magic of “Staged” Combustion

Combustion is affected by the ratio of fuel and oxygen. In outdoor boilers, the fuel is the smoke that occurs after the wood, coal, or biomass is burned with only a limited amount of oxygen. Restricting the oxygen results in a controlled fire that “vaporizes” the wood, causing smoke.

Burning smoke

We are so often used to watching the smoke rise from a campfire it is strange to think about burning smoke, but that is exactly what an outdoor boiler does through the gasification process. In this next step, additional oxygen is mixed with the smoke and introduced to the lower combustion chamber to achieve the optimal level of combustion. Efficient and effective combustion is greatly affected by the ratio of fuel (smoke) to oxygen.

Put your boiler on cruise control

This is a precise process, so we added our advanced oxygen sensor which automatically adjusts the fuel to air ratio so you don’t have to. This innovative technology allows your HeatMasterSS furnace to achieve longer burn times and reduced fuel consumption.

How Our Air to Fuel Ratio Control Works

The air intake opens and closes, controlling the amount of air in the firebox to ensure the fuel burns efficiently at every stage of the cycle. If there is too little oxygen in the lower chamber, the upper air will flood the combustion, just like flooding an engine. By adding the precise amount of oxygen required the air to fuel ratio control allows for the cleanest and most complete combustion possible.

When the HeatMasterSS furnace enters a heating cycle, the upper and lower dampers open to begin the combustion process. If there is too little oxygen in the lower chamber, the lower damper opens injecting more oxygen to prevent “flooding”. If the lower damper is fully open, and the oxygen level is still too low, the upper damper will begin to close, limiting the amount of smoke produced until the lower chamber catches up. This modulation continues throughout the burn cycle with the upper and lower dampers continuing to adjust.

Getting the right amount of BTUs

The target oxygen level for the optimal burn is usually 5-6%. However, this may need to be adjusted based on the type of wood being used. Wood with a higher moisture content requires more oxygen to burn efficiently.

Additionally, if too much air is introduced, it is likely that the furnace will produce more BTUs than the heat exchanger can handle. This results in BTUs being lost through the exhaust. HeatMasterSS air to fuel ratio control ensures that the amount of air introduced is always at the right level to achieve the desired BTUs.

Reducing creosote maintains proper airflow

The air injection panels in the HeatMasterSS furnaces help to create a more even burn. the firebox to stay creosote free and creates an even burn. Having the right amount of oxygen ensures that the fuels burn cleanly and evenly.

Creosote, a black tar that occurs when smoke and ash combine with moisture inside your outdoor furnace. Excess creosote can reduce airflow through the boiler preventing the boiler from operating cleanly and efficiently. By controlling the airflow ratio in your furnace, HeatMasterSS minimizes creosote buildup, keeping airways open and your furnace working with little effort.

The HeatMasterSS Advantage

We know that time is a commodity that you can’t get back which is why HeatMasterSS engineers furnaces to make your life easier. We focus on providing you with innovative features that save you time and effort while avoiding the mess. Our modulating air dampers and oxygen sensors keep you in control of your energy.

An outdoor furnace is a long term investment in the safety and comfort of your family. We give you the features, advantages, and benefits you need for your lifestyle and independence. Our dedicated staff is continually researching new and innovative ways to improve and perfect our products.

When you are looking to heat your home, it’s good to know that your outdoor furnace is backed by an extensive network of local, professional dealers.

Find the right outdoor wood furnace for your heating needs.