Functional Devices

About Functional Devices

Functional Devices has built a strong reputation as a leading American designer and manufacturer of control devices for the HVAC, building controls, and energy management industries. Founded on the principle that reliable, precision-engineered components are the backbone of any well-functioning building system, Functional Devices has become a go-to name for contractors, engineers, and facilities managers who demand consistency and quality from their electrical control hardware.

What sets Functional Devices apart is their commitment to domestic manufacturing. Every product is designed and built in the United States, ensuring tight quality control and shorter lead times compared to overseas alternatives. Their catalog of over 200 products covers the critical electrical and control components that keep commercial and residential HVAC systems running safely and efficiently.

Transformers for HVAC and Building Controls

One of Functional Devices' most recognized product lines is their lineup of Transformers. These step-down control transformers are engineered specifically for HVAC applications, converting line voltage down to the 24VAC signal voltage that thermostats, zone valves, and control boards depend on. Functional Devices transformers are designed with built-in overcurrent protection and a range of VA ratings to match virtually any residential or commercial application.

Relays, Fan Sequencers & Automation Controls

Perhaps the product line Functional Devices is best known for is their Relays & Fan Sequencers. Their iconic RIB® (Relay in a Box) series revolutionized the industry by packaging a fully enclosed, plug-in relay into a compact, universal-mount enclosure — eliminating the need for a separate panel or DIN rail in many installations. Fan sequencers from Functional Devices help stage multi-speed blower motors and electric heating elements efficiently, reducing electrical stress and improving system longevity.

Motor & Electrical Parts and Accessories

Beyond their flagship lines, Functional Devices also offers a selection of Motor & Electrical Parts & Accessories that complement their control systems. These components are designed to integrate seamlessly with Functional Devices transformers and relays, making it straightforward to build or service a complete control circuit without sourcing parts from multiple vendors.

Accessory Power Relays

For applications requiring switched power control, Functional Devices produces Accessory Power Relays suited to a variety of load types. These relays provide dependable switching action for auxiliary equipment loads, and their robust construction reflects the same durability standards applied across the entire Functional Devices product range.

Why Choose Functional Devices?

• American-designed and manufactured for consistent quality and reliability
• Extensive product range covering transformers, relays, sequencers, and accessories
• Industry-leading RIB® relay platform with universal mounting flexibility
• Products engineered specifically for HVAC, building automation, and energy management systems
• Trusted by HVAC contractors, electrical engineers, and facilities professionals nationwide