Skip to content
Fan in a Can


Field Controls Introduces the New “Fan in a Can” CAS-34U

(Kinston, NC  |  May 1, 2023) –  Field Controls would like to announce the launch of a new product, the CAS-34U Combustion Air System. The universal design of the CAS-34U combines the CAS-3 and CAS-4 units. The original CAS-3 was designed for 120V control systems and the CAS-4 for 24V control systems. The new CAS-34U model, also known as the “Fan in a Can,” is now capable of switching from 120V to 24V applications, and the new model also features an electronic control. This simplifies two models into one, reducing inventory and leading to cost savings.

The “Fan in a Can” Combustion Air System diffuses the outside air into the room near the appliance burner to ensure adequate air for efficient combustion. The purpose of the  CAS-34U is to provide combustion air for appliances. According to NFPA 54 and NFPA 31, an engineered system may be used to overcome the lack of air in a confined space. This product is designed for use with any oil, natural gas, or LP burning furnace, water heater, or boiler when direct connection to the burner is not possible (when the appliance is located in a confined space). The CAS-34U may also be used in combination with a 30mV standing pilot gas water heater with the use of an additional CK-20 series control kit. Additional 120V or 24V controlled appliances may also be served by the CAS-34U with the addition of one CAC-120 or CAC-24 control kit. The CAS-34U also relieves depressurization, enabling proper venting of combustion appliances, as well as other exhausting appliances such as range hoods and bath fans.

See also  Why Hydrogen Peroxide Air Purification is Shaping the Future

Moving forward, the CAS-34U will replace the CAS-3 and CAS-4, which have been discontinued. If replacement products are needed, you will be supplied with the CAS-34U, however, we will continue to offer product support for the CAS-3 and CAS-4. If you have any questions or concerns, please contact Tech Support at or 800-742-VENT (8368).

About Field Controls

As experts in air treatment, air quality, and air control, we have provided homeowners with the highest quality and best-performing indoor air solutions since 1927.


Press Contact

Nicole Edwards
Director of Marketing


Brochures PDF
Brochures PDF Link

Nicole Edwards

Back To Top