A new air-temperature sensor from Spectrum Sensors and Controls (St. Marys, PA, U.S.) is said to be both easy to install and rugged, and has the ability to accurately sense the ambient air temperature in air-handling units and heat pumps.

John Sidoni, engineering manager from Spectrum, says that the sensor is currently the only one of its kind. “No one has looked at the specific needs of the HVAC OEMs who need to sense ambient air temperature as part of their system,” he explains. “Some designs are relatively simple to install, but do not accurately sense temperature, while others are accurate, but are not rugged or are costly and time-consuming to install.”

Rather than having to utilize special mounting screws or equipment, the sensor is designed to be snapped into place, saving a great deal of time and cost on the production line. According to Sidoni, most previous air sensors were surface-type sensors that were mounted directly to a face of the sheet metal, which would cause it to sense the temperature of the sheet metal more so than the ambient air. “This new snap-in sensor allows the sensing element to be thermally isolated from the sheet metal so that it can accurately sense the temperature of the ambient air,” Sidoni says.

The sensor’s fast response thermistor element is integrated into a potted metal housing that can be snapped into a 0.30-in.-diam predrilled hole in 14- to 18-gauge sheet metal. This is designed to keep the sensor off the sheet metal while the plastic-molded body with strain relief thermally separates the assembly from the environment on the backside. Sidoni says the composition of the retaining clip allows for the part to be accurately and securely positioned so that it can correctly sense the air temperature.

Although applicable to any HVAC system, Sidoni says heat pump engineers may especially benefit from the new sensor. “For all heat pumps, the ambient air temperature is very important in the control of the system,” Sidoni says. “The air sensor needs to be a part of the overall system rather than a separate assembly in order to keep the cost down and simplify installation. This new snap-in sensor can be easily installed on the manufacturing line and will be ready to accurately sense temperature once the units are installed in the field.”

To integrate the sensor in existing designs, Sidoni says the HVAC equipment engineer would need to find a small area internal to the system where the sensor could be installed. “A small hole for the sensor would need to be designed into the manufacture of the appropriate panel, and the sensor would be ready to be snapped in on the line, which would be very quick and simple,” Sidoni says.

The sensor assembly is available in a wide range of sensor values and curves to make it compatible with most HVAC control systems. Additionally, the design can be customized to change lead lengths and add connectors to meet the specific needs of HVAC OEMs.