Field Controls 603400700 Air System

The Field Controls 603400700 CAS-34U Fan-in-a-Drum Combustion Air System is a universal air supply solution engineered to provide a dedicated source of combustion air for oil or gas-fired appliances. This unit is the designated replacement and cross-reference for the discontinued 46266301 and 46266302 models. Designed for versatility in the field, it features dual voltage compatibility, operating on either 24VAC or 120VAC control circuits. This system effectively mitigates negative pressure issues in tight mechanical rooms, supporting oil burners up to 3.5 GPH and gas-fired equipment up to 450,000 BTU. The Fan-in-a-Drum design allows for a low-profile installation where traditional passive venting or large duct runs are impractical. By delivering a pressurized air supply directly to the appliance, the CAS-34U ensures consistent draft and optimal combustion efficiency across natural gas, LP, or oil applications.

Key Technical Benefits

• Universal Compatibility: Serves as a direct replacement for multiple previous Field Controls iterations, simplifying inventory and field replacement.
• Enhanced Safety: Includes a pressure sensing switch to ensure the fan is operational before the burner is allowed to fire, preventing localized oxygen depletion.
• Flexible Integration: Seamlessly interfaces with power stack dampers, 120V or 24V controllers like the CAC-120 or CAC-24, and even 30mV millivolt systems when using a CK-20FV kit.
• Space Optimization: The compact housing fits into restricted spaces, providing a 4-inch intake connection to pull fresh air from the exterior.
• Reliable Performance: Engineered for continuous duty to maintain stable flame patterns and reduce soot buildup caused by inadequate air-to-fuel ratios.

Common Technical Questions

Can I use the CAS-34U with a water heater and a furnace simultaneously?
Yes, by utilizing the CAC-120 or CAC-24 multiple appliance controllers, you can interlock the system with multiple units to ensure sufficient air is provided regardless of which appliance cycles on.

Does this unit replace the older CAS-3 and CAS-4 models?
The CAS-34U is the universal successor designed to cover the applications previously handled by the CAS-3 (oil) and CAS-4 (gas) models, consolidating them into one SKU for easier field application.

What size intake pipe is required for this system?
The unit is typically paired with 4-inch diameter intake piping, though longer runs may require adjustments based on the total equivalent feet of the venting path to maintain required airflow.

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.