Nowadays, all of the major rooftop unit manufacturers are installing control packages into their units and more and more Facilities Managers are investing in smarter HVAC equipment. However, since rooftop units are a sizable investment, it’s important for managers to understand the why for an upgrade. One of our HVAC gurus of 10 years, Eric Kelly, explains his observations of the evolution of RTU control technology.
Q: Eric, what is are RTU controls useful for? How does the common end-user benefit?
The Rooftop Unit (RTU) controls the amount of air and the temperature that flows into the facility. Now, think of the control platform as the brains of the RTU. It makes pre-set temperature decisions for the facility manager’s indoor air environment. RTU controls give options and functions that allow the rooftop units to operate more efficiently and make the facility more comfortable.
Using an analogy, if the RTU is a Ferrari on top of your roof, then the controls platform is the Ferrari’s built-in GPS or on-board computer that tells the most efficient route and puts less wear and tear on your expensive vehicle. With rooftop equipment often adding up to the cost of a Ferrari, who wouldn’t want control over your investments’ performance?
Lennox Control Board
Lennox 1st Generation Prodigy Board
Lennox 2nd Generation Prodigy Board
Trane’s Voyager Unit with ReliaTel Controls Interface
Q: How does it make a facility more efficient and comfortable?
Older units that don’t have controls require messing with the set point and adjusting mechanical changes, such as changing the size of belts and pulleys, to set the RTU’s proper airflow. Now, with RTU controls, you can make those changes digitally without hardware adjustments, as with belts and pulleys. The digital capability allows for accuracy and fine tuning with less trial and error.
Most RTU manufacturers offer this technology with their units and have all made improvements to it over the years. We have worked with controls from all the main manufacturers—Lennox, Trane, Carrier, York, and Aaon.
Q: How have RTU controls evolved? How has accuracy and usability changed?
I’ve seen great improvement in the usability of the interface. In my earlier days, I saw the older version of the technology, which were standard circuit boards with switches allowing you to perform certain functions. A specific example of this was the Lennox Control Board (pictured above), which had 1 push button, dip switches, and a 3-digit digital display. Users had to press 1 button to cycle through to different settings. Now the newer generations of RTU controls have improved the flow of the menus and have more intuitive buttons.
A second improvement over the evolution of RTU controls is how it can be integrated with a building’s Energy Management System.
Q: Are you saying that all existing facility RTUs need to be replaced with those that have a control platform?
If your facility goals involve optimization of your HVAC equipment, then I’d suggest an upgrade. That being said, if your RTUs don’t have this technology, then it doesn’t mean it can’t be optimized, it just means you or your contractor will just spend more time and skill to get it just right.