Installation Instructions for Modine CAS-2B Field Control AIRBOOT™ Outside Combustion Air Kit
A comprehensive installation guide for the Modine CAS-2B AIRBOOT™ kit, designed for Model POR units with Beckett AF burners. Includes step-by-step assembly, VRV installation, ducting requirements, and burner start-up adjustments.
Table of contents
Quick guide from the manual
The CAS-2B AIRBOOT™ kit is designed to provide outside combustion air to Modine Model POR units equipped with Beckett AF burners, particularly in buildings with inadequate makeup air or negative pressure. Installation must be performed by a qualified service agency. Before starting, ensure the fuel supply is shut off and electrical power is disconnected.
Kit Components
- AIRBOOT™ unit
- Burner housing gasket set
- Mounting screws (1/4-20 x 1-1/4)
- Extended coupling (#21775)
- Vacuum Relief Valve (VRV)
- Intake Air Hood (IAH)
AIRBOOT™ Installation
- Remove the fuel pump, air shutter, and air band from the burner housing.
- Replace the original shaft coupling with the provided extended coupling (#21775).
- Install the sealing gaskets to the burner housing.
- Position the AIRBOOT™ over the burner housing intake side.
- Align holes, guide the pump shaft into the coupling, and secure with mounting screws. Do not overtighten.
The AIRBOOT™ can be oriented vertically or horizontally by adjusting the spacer ring using the plastic fasteners.
Vacuum Relief Valve (VRV) Installation
The VRV provides a secondary air opening if the Intake Air Hood is blocked. Mount the VRV tee assembly or 90° elbow into the AIRBOOT™ intake using three sheet metal screws. Assemble the balance weight onto the gate, ensuring it is level and plumb across the pivot point.
Intake Air Hood and Ducting
Mount the Intake Air Hood at least 12 inches above the finish grade or snow line. Cut a 4-1/4 inch hole in the wall, insert the hood, and seal with silicone. The maximum duct length is 34 equivalent feet (20 feet straight pipe plus two 90° elbows). Tape all joints with foil or duct tape. In cold climates (below -10°F), insulate the duct for at least 10 feet from the hood.
Burner Start-Up and Adjustment
After installation, set the initial AIRBOOT™ air dial (250° for POR100/145, 260° for POR185). Perform a smoke test and adjust the air dial until a trace of smoke is obtained. Measure CO2 levels and adjust the air dial until CO2 is between 11.5% and 12.5% with zero smoke. Tighten the lock screw after final adjustments.
Maintenance
Periodically check the Intake Air Hood and the 1/4 inch mesh screen for debris. Verify the VRV operates freely and perform a smoke test during annual servicing.
Practical help
Common problems
The Vacuum Relief Valve (VRV) will automatically open to stabilize airflow to the burner.
Insulate the duct work for at least 10 feet from the Intake Air Hood if operating in temperatures of -10°F or below.
Perform a smoke test and adjust the AIRBOOT™ air dial until zero smoke is achieved.
Before use
- Ensure fuel supply is shut off and electrical power is disconnected.
- Verify the unit is a Modine Model POR with a Beckett AF burner.
- Check that the duct run does not exceed 34 total equivalent feet.
- Ensure the Intake Air Hood is mounted at least 12 inches above grade/snow line.
- Confirm the VRV gate is level and plumb across the pivot point.
Specs in practice
- Maximum Duct Length
- 34 total equivalent feet (20' straight + two 90° elbows at 7' each).
- Over-fire Draft
- Should be -0.02" W.C. when burner air supply is properly adjusted.
Images and diagrams
- Figure 1: Exploded view of AIRBOOT™ and gasket assembly.
- Figure 2: Vertical vs. Horizontal orientation options.
- Figure 4: Proper installation of the VRV tee assembly.
- Figure 5: Balance weight and gate assembly for the VRV.
- Figure 6: Leveling requirements for the VRV pivot point.
Model compatibility
- Specifically designed for Modine Model POR units with Beckett Model AF burners.
- Not for use with the original inlet air shutoff; it must be removed.
- Flow Restrictor (part #31990) is NOT used with Modine model POR units.
Manual page author
Emily Carter
User documentation editor
Prepares concise manual descriptions and highlights the most useful setup, operation, and maintenance information for readers.