HVAC controls in Florida operate on a cooling-dominant duty cycle: compressors, fans, and condensate pumps run most of the year rather than seasonally, and switching cycles and runtime hours accumulate accordingly. Functional Devices, Inc. manufactures RIB® (Relay-In-a-Box®) relays and current sensors for building automation, including models suited to the low current draw of electronically commutated motors (ECMs).
Relays in Florida HVAC Control
A relay handles low-voltage signal switching, building automation system (BAS) output isolation, fan coil control, and staging. The RIBU1C is an enclosed relay rated 10 Amps SPDT with a 10–30 Vac/dc or 120 Vac coil and a dry contact output, which lets a controller output switch a load without passing power from the coil.
Motor Status on Long-Runtime Equipment
A current switch reads the actual draw at the equipment, which distinguishes a running motor from a commanded-on point that did not start. On equipment that runs near-continuously, a wrong status point can stand uncorrected for longer: a failed fan or condensate pump will report as running until someone discovers that it isn’t. Florida’s latent load produces condensate year-round, so a current switch on the condensate pump reports actual operation rather than an assumed one. The RIBXGTA is a split-core adjustable current switch with a 0.75–150 Amp sensing range and a dry contact output; split-core models can be installed around an existing conductor without disconnecting wiring.
ECM Current Sensing in Florida HVAC Systems
An ECM draws standby current whenever it is powered on; but at low speed, its running draw sits only slightly above standby, so a current sensor for ECMs must be able to distinguish between the two. The RIBXGTA-ECM adjusts down to 0.25 Amps, and its LED indicators guide trip-point setting during commissioning. Set the trip point with the motor at its lowest normal operating speed: above the standby draw, at or below the lowest running draw.
Staging Multiple Units on Florida Rooftops
Many Florida commercial buildings run several rooftop units off the same electrical service. Starting them all at once creates a combined inrush current well above what the units typically draw, which can trip a breaker sized for normal operating current. A relay lets the BAS start the units one at a time instead: the controller closes one relay, that unit starts and stabilizes, and a time delay closes the next. In Florida, where rooftop units already run more of the year than in a shorter cooling season, this staged startup also keeps demand-charge spikes lower than starting all of the rooftop units at once would create.
Frequently Asked Questions About HVAC Controls in Florida
How do I confirm a fan is running?
A current switch reports whether a motor is drawing running current.
Where do I set the trip point on an ECM?
Run the motor at its lowest normal speed, then set the trip point above the standby draw and at or below that lowest running draw. The RIBXGTA-ECM’s LED indicators show whether the sensed current is below, in, or above range during setup.
What relay works for fan coil switching?
The RIBU1C is the commonly specified device when the load is 10 Amps or less and the control signal is 10–30 Vac/dc or 120 Vac. Above 10 Amps, or for motor loads with high inrush, check the contact ratings on the datasheet for the specific model.
Can one relay control multiple staged units?
No. Each stage needs its own relay so the controller can turn each unit on independently on its own schedule. The RIBU1C is rated for a single SPDT contact, so staging several units calls for one relay per stage, each triggered by its own BAS output.
What is a dry contact output, and why does it matter for BAS integration?
A dry contact output switches a circuit without carrying voltage or current from the relay itself, which isolates the controller’s low-voltage side from the field device it’s switching. This lets a building automation system output control a load, such as a fan or pump, without exposing the controller to that load’s voltage or inrush current.
Do I need to disconnect wiring to install a current switch?
No, not for split-core models. A split-core current switch such as the RIBXGTA opens to install around an existing conductor, so it doesn’t require breaking the circuit or disconnecting existing wiring.
Source RIB Relays and Current Sensors for Florida HVAC Work
Functional Devices’ RIB® relays are built to withstand Florida’s cooling-dominant duty cycle. The RIBU1C carries a rated mechanical life of 10 million cycles minimum, well beyond what Florida’s higher switching volume would use over a building’s service life. An authorized distributor can confirm availability on the RIBU1C, RIBXGTA, RIBXGTA-ECM, or any other Functional Devices product. Find an authorized Functional Devices distributor in Florida before the next cooling season.