Did you know that the first air conditioner was invented in 1902 by Willis Carrier? Since then, air conditioning technology has evolved dramatically, and today, many buildings rely on Rooftop Units (RTUs) to maintain comfortable indoor environments.
RTUs handle more than just heating and cooling. Many also manage humidity and air quality to keep conditions just right. Controlling these units efficiently can be challenging, especially when trying to integrate them into a building automation system.
The Functional Devices’ “Relay-In-a-Box®” (RIB) Trifecta is a versatile solution that simplifies RTU control while maintaining reliability and flexibility. It’s an all-in-one solution that combines a power supply, relay, and current sensor into a single compact device. In this blog, we’ll explore how the RIB Trifecta can enhance RTU operation, simplify wiring, and optimize energy use, making it an essential tool for facility managers and system integrators.
Functional Devices has been designing and manufacturing reliable relays and building automation solutions for over five decades, with products trusted in HVAC, lighting, and energy management applications. If you’re looking to simplify RTU control with the RIB Trifecta, contact our team today to find the right solution for your project.
RTU Basics
RTUs provide centralized heating, cooling, and ventilation, often for commercial spaces such as offices, schools, or retail buildings. They typically include compressors, fans, and sometimes economizers, all of which need precise coordination to operate efficiently.
In most RTUs, you'll find a fan to pull air from the building and heating and cooling coils to condition the air before that same fan pushes the air back down into the building. At the heart of all this equipment is the control system. The control system takes readings from sensors and tells the equipment how to react to create a comfortable environment for the occupants, making it a key part of the best building automation solutions for any facility.
Common challenges in RTU integration include:
- Coordinating multiple units to avoid energy waste
- Managing fan and compressor staging for comfort and efficiency
- Integrating with building automation systems that require multiple control points
A reliable, flexible relay like the RIB Trifecta helps address these challenges by providing streamlined control options and reducing the need for multiple relays.
What Is the RIB Trifecta?
The RIB Trifecta is a multi-functional relay designed to handle a variety of control applications in building automation. Unlike standard RIB relays, the Trifecta combines multiple control features and devices in a compact footprint, offering:
- Three independent contact sets in a single device (power supply, relay, current sensor)
- High reliability for commercial HVAC applications
- Compact size for easier panel installation
- Versatility for switching multiple loads with a single relay
This combination makes it ideal for controlling RTUs, allowing facility managers to simplify system design while maintaining precise control over critical HVAC components.
How Functional Devices' Trifecta Supports Your RTU
Functional Devices' Trifecta is the perfect set of accessory components to include in your RTU applications to power the control system, enable equipment, and verify operation. Let’s dig into some of the technical details.
Power Supply
The power supply, as the name suggests, supplies power to the control system. The controller and all the accessories use 24 volts AC (Vac). The power supply reduces the voltage from 120Vac to 24Vac, but it also has a few extras to make life easier for the installers and technicians who work on the equipment.
For example, a PSH75A will have a breaker to protect the transformer in the event of an overload. It also has terminal strips for the wiring to land on, and it even has a 120Vac receptacle for a service technician to plug his laptop into, in case he needs to make adjustments to the control system.
Relay
Relays are used to switch equipment on and off from the control system. You'll find a relay enabling fan contactors, stages of heating or cooling, and sometimes commanding dampers open or closed.
You can even mount the NEMA 4 rated RIB2401C-N4 to the outside of a control cabinet so you can see the LED indicator without opening any of the panels, which makes troubleshooting a faulty unit easier.
When the fan command is sent, the controller will often look for a status before enabling heating or cooling stages. The RIBXKTF is a cost-effective current switch that can be installed on one of the fan's current-carrying conductors, watching for current flow. Once current is detected, we know that the fan is running, so the controller can enable heating or cooling.
Current Sensor
Some of our RIB relays, like the RIBXKTF we just discussed, are a two-in-one relay and current sensor. But you do have the option of having separate devices. Current sensors give your control system the proof it needs that equipment is actually operating.
For example, when a fan command is sent, the controller will often require verification before enabling heating or cooling. A model like the afore-mentioned RIBXKTF can be installed on one of the fan’s current-carrying conductors to detect current flow, confirming the fan is running so the controller can safely enable the next stage.
For applications where a compact sensor is preferred, the RIBXGTF offers similar functionality in a smaller footprint. Both models provide reliable, cost-effective feedback for fans, pumps, compressors, and other loads, making Functional Devices current sensors an easy way to improve safety, efficiency, and troubleshooting in RTU control.
Frequently Asked Questions About the RIB Trifecta
Q: What is the RIB Trifecta?
A: The RIB Trifecta is a three-in-one device from Functional Devices that combines a relay, a current sensor, and a power supply in one compact unit. It’s designed to streamline rooftop unit (RTU) installations and other HVAC control applications by reducing the number of separate components you need.
Q: Why should I use the RIB Trifecta instead of individual components?
A: By combining three functions into one device, the Trifecta saves space, simplifies wiring, and reduces installation time. It also lowers the number of components that need troubleshooting or maintenance, which cuts down on long-term costs.
Q: What applications is the RIB Trifecta best suited for?
A: The Trifecta is ideal for rooftop units, air handling units, fan control, pumps, and other HVAC systems where you need all three components — a relay for control, a current sensor for status feedback, and a power supply for powering devices.
Q: Which models are available?
Functional Devices offers Trifecta models with different configurations of components. It’s really up to you and what you need! One of our engineers would be happy to help you figure out the right combination for your specific application.
Get Control of RTUs with Functional Devices
The Functional Devices’ RIB Trifecta power-supply-relay-current-sensor combo is a powerful, versatile solution for controlling RTUs in commercial HVAC systems. Its compact design, multi-contact functionality, and reliability make it an excellent choice for simplifying RTU integration and improving energy efficiency.
At Functional Devices, we pride ourselves on creative design that prioritizes efficiency and functionality. Contact our technical support team to find the best configuration of the Trifecta for your HVAC and building automation systems.
About Functional Devices, Inc.
Functional Devices, Inc., located in the United States of America, has been designing and manufacturing quality electronic devices since 1969. Our mission is to enhance lives in buildings and beyond. We do so by designing and manufacturing reliable, high-quality products for the building automation industry. Our suite of product offerings include RIB relays, current sensors, power controls, power supplies, transformers, lighting controls, and more.
We test 100% of our products, which leads to less than 1 out of every 16,000 products experiencing a failure in the field.
Simply put, we provide users of our various products confidence and peace of mind in every box.