Combustion Air Requirements For Oil Burners

Bulletins, Burners, General

o understand why oil burners need combustion air, let’s review the basics of how combustion occurs. Three elements must exist together in order for combustion to take place:

  1. A source of fuel, whether it is oil for an oil burner, wood for a fireplace, or rocket fuel for a rocket.
  2. A source of ignition to start the process of combustion, for instance a spark, a flame, or a hot surface. In most cases, once the process is started, the heat of the combustion is adequate to sustain continued combustion.
  3. A supply of oxygen to support the combustion process, whether it is room air for oil burners, bottled gaseous oxygen for welding torches, or liquid oxygen for rockets.

If any one of these three ingredients is missing, combustion will not take place.

CombustionFig1

 

CAUSES FOR LACK OF COMBUSTION AIR

A house which has a tight construction does not allow adequate airflow for combustion into the house. This problem is compounded by having multiple air-using appliances, fireplaces, and exhaust fans operating at the same time as the oil burner. A tightly sealed furnace / boiler room will create the same condition.

Another cause of the lack of combustion air is the environment in which the burner operates. If the burner draws air from an environment which has a large amount of dryer lint and animal hair, the air delivered to the combustion zone may be restricted due to clogging of the air openings, blower wheel, or combustion head.

One of the first noticeable signs of a lack of combustion air could be the odor of combustion products in the building. More than one air-using appliance running simultaneously may depressurize a tightly sealed building, causing a backdraft in one or more of the appliances. This condition could cause flue products to be pulled back through the chimney / exhaust system and into the building.

When combustion is deprived of the necessary oxygen, the correct ratio between the air and fuel changes to a fuel-rich, air-lean ratio. This causes an oil flame to become bright, orange, and soot-producing. In the case of a tightly sealed building, a burner which is operating cleanly might generate smoke as soon as another air using appliance is started.

Combustion test equipment is required to check the flue gas products. When you are performing the initial setup of a burner, if the flame does not burn cleanly, inadequate combustion air may be the cause. To determine quickly if this is the problem, open an outside door or window and perform the combustion and smoke tests again. If the flame now burns cleanly with the door or window open, lack of combustion air is most likely the problem.

One method of compensating for insufficient air is to supply outside air directly to the oil burner. An outside air intake kit is available which allows the ductwork to be coupled directly to a Beckett model AF or AFG burner. This kit (#51747, shown below in Figure 2) replaces the Beckett outside air intake kit #5753. The boot can be mounted either horizontally or vertically, as shown in Figure 5 below. Be sure to follow the manufacturer’s instructions for installation of the Airboot™, intake air hood, air supply duct, vacuum relief valve, and exhaust terminal.

CombustionFig2-3

THE VACUUM RELIEF VALVE

As shown below in Figure 4, the Beckett model AFII burner has a built-in receptacle that allows an outside combustion air duct to be connected directly to the burner.
CombustionFig4

The vacuum relief valve (VRV) is installed in an unconfined area to provide a secondary opening in the duct system for combustion air supply. This is especially important in the event of damage or blockage of the intake air hood.

The VRV gate operates when changes occur in vacuum pressure generated between the air intake and the oil burner. The VRV gate remains closed during normal burner operation. If any blockage of the intake air hood or duct pipe occurs, or if significant changes in external building pressure occur, the increased negative pressure on the intake of the burner opens the VRV gate, which stabilizes and maintains proper air flow to the burner. The VRV gate closes again once the abnormal condition is corrected.

 

AIR REQUIREMENTS

A burner operating in an unconfined space in a conventional frame, brick, or stone building will usually receive adequate air supply from normal air leakage into the building. However, if the building is tightly sealed, air must be supplied from the outside. A permanent opening to the outside (or to an area that receives air flow from the outside) is necessary, and the opening or openings must have a total free area of at least one square inch per 5000 Btu per hour, or 28 square inches per GPH of #2 fuel oil.

If the burner is located in a confined space such as a furnace or boiler room, the air requirements depend on the source of the ventilation and combustion air:

  1. If both the ventilation air and combustion air are to be drawn from inside the building, there must be two openings, one near the top and one near the bottom of the enclosed space. Each opening must have at least one square inch of free area per 1000 Btu/hour (140 in.² per GPH). See *Example.
  2. If both the ventilation air and combustion air are to be drawn from outside the building, there must be two openings, one near the top and one near the bottom of the enclosed space. Each opening must have at least 1 square inch of area per 2000 Btu/hour (70 in.² per GPH) if horizontal ducts are used, or at least 1 square inch of area per 4000 Btu/hour (35 in.² per GPH) if vertical ducts are used.
  3. If ventilation air is to be drawn from inside and combustion air is to be drawn from outside, there must be two openings, one near the top and one near the bottom of the enclosed space, each with at least 1 square inch of area per 1000 Btu/hour (140 in.² per GPH). Also, there must be one opening (to the outside) for combustion with at least 1 square inch of area per 5000 Btu/hour (28 in.² per GPH).

To summarize, for combustion air, an opening is needed that has at least 28 in.² of free space per GPH of #2 fuel oil. For ventilation air, two holes are needed, each with at least 140 in.² of free space per GPH (divide area by 2 for outside air; divide by 2 again for vertical ducts). Remember to take the total input of all air-using appliances into consideration when calculating the opening sizes. Refer to the NFPA 31 Standard (Chapter 1) and local codes for more information about combustion and ventilation air requirements.

*EXAMPLE CALCULATION: If an oil furnace is firing at 1.25 GPH and a water heater is firing at 0.50 GPH, two openings to the inside space of the building must each have at least 245 square inches of free area (1.25 GPH + 0.50 GPH = 1.75 GPH; 1.75 GPH x 140 square inches = 245 square inches). A 245 square inch opening would typically be 10″ x 25″ or 16″ x 16″.

 

SERVICE OF AN OUTSIDE AIR INTAKE SYSTEM
  1. Check the intake air hood and air supply for accumulation of any foreign material. Give special attention to the mesh screen inside the intake air hood. Thoroughly clean all foreign material from the system.
  2. Note any damage to the air supply components and replace with exact system components.
  3. Verify that the VRV is operating properly.
  4. Verify that the over fire draft is set according to the manufacturer’s recommendations (usually -.01″ to -.02 ” W.C.). Be sure that the firing rate of the appliance does not exceed the specifications in the tables below.
    1. Using combustion test instruments, perform a smoke test. Adjust the air setting until a trace of smoke is obtained. This is a reference point only. Do not leave the air settings here.
    2. Measure the CO2 or O2 in the flue gas at the trace of smoke level. Then open the air adjustment to add reserve air until the CO2 is lowered by at least 1.5% (or the O2 is raised by at least 2%).
    3. Perform a smoke test again. The smoke paper should now be clean (zero smoke). Securely tighten the air adjustment at this setting.

SUMMARY

Combustion air requirements are probably one of the most important and most neglected aspects of proper combustion. An adequate supply of combustion air is vital to the performance and continued operation of the heating unit. This outline of combustion air problems and solutions should assist you in maintaining a trouble-free, soot-free installation. The next time you take a deep breath, remember to check that the oil burner also has the capacity to “breathe” plenty of fresh air without restriction.

 

APPROXIMATE AIR DIAL SETTINGS – BECKETT OUTSIDE AIR INTAKE KIT #51747

(Based upon 30 linear ft. of 4″ duct, two 90° elbows, and an Intake Air Hood) Read notes carefully!

AF Burner-Maximum Firing Rates for Negative Overfire Drafts (approx. -.02″ W.C.)

HEAD F0 F3 F4 F6 F12 F16 F22
STATIC PLATE G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING
2 – 3/4 U* 0.75 195° 1.14 260° 1.19 250° 1.37 260° 1.56 260° 1.75 260° 1.83 260°
3 – 3/8 U* 0.69 225° 1.07 260° 1.14 250° 1.28 260° 1.49 260° 1.57 260° 1.70 260°
3 – 3/8 R* 0.62 250° 0.95 260° 1.10 250° 1.20 260°
3 – 5/8 R 0.89 260°

 

AFG Burner-Maximum Firing Rates for Negative Overfire Drafts (approx. -.02″ W.C.)

HEAD F0 F3 F4 F6 F12 F16 F22 F22 F22 F22
STATIC PLATE G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING
2 – 3/4 U* 0.75 55° 1.25 90° 1.35 120° 1.58 260° 1.84 260° 2.05 260° 2.23 170° 2.33 270° 1.96  270°
3 – 3/8 U* 0.75 115° 1.21 110° 1.35 145° 1.54 260° 1.78 260° 1.90 260° 2.05 260°  1.00  270°
3 – 3/8 R* 0.75 175° 1.14 140° 1.50 260°
3 – 5/8 R 1.10 155°

 

AFG Burner-Maximum Firing Rates for Positive Overfire Drafts (approx. +.05” W.C.)

HEAD F0 F3 F4 F6 F12 F16 F22 F22 F22 F22
STATIC PLATE G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING G.P.H. AIR DIAL SETTING
2 – 3/4 U* 0.75 80° 1.25 170° 1.19 250° 1.52 260° 1.71 260° 1.83 260° 2.11 140°  2.13 270°  1.83  270°
3 – 3/8 U* 0.75 155° 1.21 195° 1.35 250° 1.44 260° 1.75 260° 1.72 260° 1.89 260° 1.00  270°
3 – 3/8 R* 0.75 235° 1.14 240° 1.35 260°
3 – 5/8 R 1.10 260°

 

Notes:

  1. *Firing rates up to and including 0.75 GPH REQUIRE the installation of the flow restrictor (see Figure 2 for location).
  2. G.P.H. is the MAXIMUM firing rate for that specific combustion head. If firing below that rate, a decrease in airflow on the AIRBOOT™ dial will be required.
  3. AIR DIAL SETTINGS are initial settings. Always use combustion test instruments for final adjustment settings.

CombustionFig5

Contact Us

Drop us a line with any comments or questions!

Burner Settings

(OEM Spec Guides)

Specifications for nozzles, air tube combinations, and other initial settings.

Tech Bulletins

Service bulletins and product updates.

Tutorials

Training videos and PowerPoint presentations.

Troubleshooting Guides

Solutions to common issues.

Find A Part

Look through exploded views to find the part you need.

Manuals & Guides

A library of product manuals and supplemental guides.

Product Warranty

View the limited warranty for all Beckett products.

Return Material Authorization

Submit a return material authorization (RMA) Request.

Warnings

(Proposition 65)

Frequently asked questions, and a list of affected products.

Classroom Training

Hands-on, practical installation, application, and operation training on Beckett’s latest products — in-person with the industry’s foremost authorities. Register today.

Online Training

Informative and technical training resources from the leading experts in the heating industry — now available online, on-demand, and FREE.

Product Instructional Videos

Our most popular product-related instructional / training videos for the most relevant and widely seen products and applications you’ll find in the field.

Find a Distributor

Beckett solutions are available through our network of distribution partners throughout the United States and Canada.

Find an Independent Representative

Beckett Independent Representatives provide Sales Support for our products throughout the United States and Canada.

Find an Export Representative

Beckett solutions are available for export outside of the United States and Canada through our network of Export Representatives.

Residential Heating Solutions from Beckett®

For over 80 years Beckett products have been the number one choice of homeowners and contractors for their furnaces, boilers, and water heaters. As North America's foremost brand of burners, Beckett continues to provide industry leading design, reliability, and support. All backed by a comprehensive warranty program that ensures you will have years of trouble-free operation.

Commercial Heating/Steam Solutions from Beckett®

As North America's leading brand of burners, you can have peace of mind in using a Beckett burner on your next commercial project. With the environment in mind, we have the most comprehensive lineup of biofuel rated burners in the industry. Supported by a broad network of trained technicians, choosing a Beckett burner for your next commercial project ensures your building will have years of trouble-free operation while reducing your equipment’s impact on the environment. A return on investment for future generations.

Road Maintenance Solutions from Beckett®

When the sun is blazing and you're responsible for keeping Americas roads maintained, you'll want a burner that's as hard working as you are. Beckett's lineup of DC burners provides mobile heat for all types of road maintenance equipment. With their ease of service and parts availability from coast to coast, you can ensure the job gets done when the heat is on.

Heated Pressure Washing Solutions from Beckett®

For over 30 years Beckett has served the pressure washer market in providing rugged yet reliable burners and components for the pressure washer industry. Our compact DC powered burners provide off-grid dependable operation in the wettest of environments. All backed by a comprehensive warranty program that ensures you will have years of trouble-free operation. So, when the "pressure" is on to get a job done, you can rely on Beckett to keep you in "hot water".

Agriculture / Greenhouse Solutions from Beckett®

With a wide range of capacities, Beckett has served the needs of the agricultural industry for over 20 years. Our proven experience in the combustion field allows us to work with appliance engineers to ensure the strictest of parameters are met when drying organic products. Beckett's modular burner platform provides the most flexibility in applications while offering the most comprehensive lineup of biofuel rated burners in the industry. This ensures efficient reliable heat for future generations.

Construction Solutions from Beckett®

When freezing temperatures hit your job sites and you need dependable heat, consider Beckett for the job. From the Arctic circle to Antarctica, Beckett has proven to be the burner of choice in the harshest most remote environments. Our robust, user-friendly design provide quick maintenance and dependable operation to ensure your site stays warm.

Food Processing Solutions from Beckett®

Beckett burners and components are used in food processing applications all over the world. From bakery ovens, coffee roasters, dehydrators, and industrial process lines, Beckett robust, reliable products reduce line down time and ensure an uninterrupted output.

R.W. Beckett

From tank to flame, Beckett delivers the most technically advanced product line in the industry — burners, igniters, controls, and accessories designed to meet the performance requirements of the industry while meeting the demands of biofuels to reduce emissions and meet carbon reduction goals. Explore all that Beckett has to offer below by selecting a brand, product category, or simply filtering through the entire product offering.

Westwood by Beckett

With the acquisition of Westwood Products in 2021, Beckett added depth and diversity to its already impressive catalog. In addition to the Tigerloop suite of Oil Dearaetors which has been transitioned to our Beckett branded offering, our Westwood by Beckett product offering includes fuel filters, electrodes, tank accessories, and many other HVAC service and repair items. The line includes B100 filters which, in conjunction with the Tigerloop Bio models, completes Beckett’s industry leading suite of B100 rated components from tank-to-flame and further positions as the market leader in the drive to alternative fuels.

Residential Heating Solutions from Beckett®

For over 80 years Beckett products have been the number one choice of homeowners and contractors for their furnaces, boilers, and water heaters. As North America's foremost brand of burners, Beckett continues to provide industry leading design, reliability, and support. All backed by a comprehensive warranty program that ensures you will have years of trouble-free operation.

RF Oil Burner

RF Oil Burner

NEW! Designed to meet the many challenges of today’s modern heating appliances and process equipment, the Beckett RF oil burner is designed to ...

Commercial Heating/Steam Solutions from Beckett®

As North America's leading brand of burners, you can have peace of mind in using a Beckett burner on your next commercial project. With the environment in mind, we have the most comprehensive lineup of biofuel rated burners in the industry. Supported by a broad network of trained technicians, choosing a Beckett burner for your next commercial project ensures your building will have years of trouble-free operation while reducing your equipment’s impact on the environment. A return on investment for future generations.

Road Maintenance Solutions from Beckett®

When the sun is blazing and you're responsible for keeping Americas roads maintained, you'll want a burner that's as hard working as you are. Beckett's lineup of DC burners provides mobile heat for all types of road maintenance equipment. With their ease of service and parts availability from coast to coast, you can ensure the job gets done when the heat is on.

Heated Pressure Washing Solutions from Beckett®

For over 30 years Beckett has served the pressure washer market in providing rugged yet reliable burners and components for the pressure washer industry. Our compact DC powered burners provide off-grid dependable operation in the wettest of environments. All backed by a comprehensive warranty program that ensures you will have years of trouble-free operation. So, when the "pressure" is on to get a job done, you can rely on Beckett to keep you in "hot water".

Agriculture / Greenhouse Solutions from Beckett®

With a wide range of capacities, Beckett has served the needs of the agricultural industry for over 20 years. Our proven experience in the combustion field allows us to work with appliance engineers to ensure the strictest of parameters are met when drying organic products. Beckett's modular burner platform provides the most flexibility in applications while offering the most comprehensive lineup of biofuel rated burners in the industry. This ensures efficient reliable heat for future generations.

Construction Solutions from Beckett®

When freezing temperatures hit your job sites and you need dependable heat, consider Beckett for the job. From the Arctic circle to Antarctica, Beckett has proven to be the burner of choice in the harshest most remote environments. Our robust, user-friendly design provide quick maintenance and dependable operation to ensure your site stays warm.

Food Processing Solutions from Beckett®

Beckett burners and components are used in food processing applications all over the world. From bakery ovens, coffee roasters, dehydrators, and industrial process lines, Beckett robust, reliable products reduce line down time and ensure an uninterrupted output.

Beckett Oil Burners

R.W. Beckett oil-fired burners were created with customer satisfaction and sustainability in mind. Our utilization of advanced components results in higher efficiency and reliability, all while reducing carbon emissions.

Our burners are suitable for a multitude of needs. They are certified for firing traditional heating oils, biodiesel blends (B20), and renewable diesel blends (R95). Truly versatile, our burners are available in AC and DC voltages and in capacities from 0.40 to 35.0 GPH. Applicable uses range from residential homes to commercial buildings, for both industrial and process installations, R.W. Beckett can meet your demands. After installation our proven burners provide years of reliable service with strong and accessible technical support.

Beckett Gas Burners

R.W. Beckett gas-fired burners were created with customer satisfaction and sustainability in mind. Our utilization of advanced components results in higher efficiency, reliability, and accessibility, all while reducing carbon emissions.

Available in capacities ranging from 250 to 5,000 MBH, our burners are suitable for a multitude of needs. Applicable uses range from residential homes to commercial, for both industrial and process installations, R.W. Beckett can meet your demands. Our burners are easy to install and service, engineered to provide years of reliable service, and backed by solid technical support and fast delivery.

Beckett GeniSys® Burner Primary Safety Controls

R.W. Beckett’s burner controls were created with customer satisfaction and safety in mind. Our entire suite of burner controls utilizes the most current technology to safely control the combustion process.

Available in both AC and DC voltages for off-grid applications, our controls are suitable for a multitude of needs. Our new GeniSys® model 7565 Advanced Burner Control is compatible with the myTechnician™ app for modernized accessibility. The app assists with diagnostics, troubleshooting, and more. With applicable uses of our controls ranging from residential homes to commercial buildings, to process applications R.W. Beckett can meet your demands. Our multitude of models offer both fixed and programmable options and serve as a direct replacement for many competitive combustion controls.

Beckett AquaSmart® Boiler Safety Controls

R.W. Beckett’s boiler controls were created with customer satisfaction and sustainability in mind. The boiler control was built using Beckett’s proprietary HeatManager® algorithm which saves fuel by minimizing operating temperature, reducing energy consumption without sacrificing homeowner comfort.

Applicable to both oil and gas-fired boilers, the control is convenient for any household. With our digital display and touch pad we have made for a more intuitive experience, allowing for flexible programming of temperature limits and other settings.

Beckett Powerlight® Igniters

R.W. Beckett igniters were created with customer satisfaction and reliability in mind. Providing an advanced option for oil-fired burners, our Powerlight® igniter also serves as a universal replacement for other manufacturers’ igniters.

Available in a variety of AC and DC voltages for off-grid applications, our product is suitable for a multitude of needs. Designed for various applications, our igniter can be found in residential homes, commercial property, and even high-moisture environments.

Beckett Tigerloop® Oil Deaerators

R.W. Beckett’s oil deaerators were created with customer satisfaction and efficiency in mind. With over 30 years of fine-tuning, the Tigerloop® is the most advanced oil deaerator in the world.

With its unmatched performance, Tigerloop® can handle capacities up to 50 GPH and is compatible with different heating fuels, depending on the model. The standard model is compatible with #1 and #2 heating oil and B5 Bioheat, while the Bio model accepts biofuel blends up to B100. Catering to many needs, our oil deaerator is also a safe, economical, and environmentally friendly choice for all supply systems.

Beckett Oil Filters

Beckett branded Spin-on filters are epoxy coated, UL Listed or UL Recognized and rated from 10 to 15 microns. Commercial Spin-on filters are rated for 52 GPH, 20 PSI, and 30 Microns. The line includes a cast aluminum tops, Filter Life Indicator (FLi™) gauge and is suitable for #1 and #2 fuel oil and rated up to B100 bio-fuels.

Westwood by Beckett canister filters feature cast iron tops and epoxy coated canisters. Element options include Classic Felt, cellulose acetate, and Classic Yarn. UL Listed/Recognized canister filters exceed GPH and pressure ratings of most competitors.

Beckett Connected Devices

R.W Beckett’s internet connected products were created with customer satisfaction and accessibility in mind. With our modernized approach, these products can be remotely accessed through our mobile app or web browser.

Through the myTechnician™ mobile app, connected products come with multiple features including troubleshooting, product programming and diagnostics. With the BeckettLink® connected tank gauge system and Wi-Fi hub, end users and oil dealers can use the Beckett Dealer Dashboard to be alerted remotely if the tank drops below predetermined levels.

For your convenience, Tank Accessories has been divided into distinct categories to help you find the products you need. Please click the links below to see all the products in each of these categories.

Beckett Electrodes and Insulators

RW Beckett manufacturers hundreds of Westwood electrodes, flame rods and spark ignitors. Many are sold through distribution and additional items are available for OEM customers for special applications. RW Beckett can manufacture specialty electrodes to your specifications. The Auburn and Champion brands are also available.

All Categories

View All Products