Honeywell Home FP280 Wireless External Flood Probe Sensor, White

The Honeywell Home FP280 is a wired external flood sensing probe designed to detect standing water and provide early warning of potential leaks through compatible Honeywell and Resideo security systems. Designed for use with the Honeywell 5821 Wireless Temperature Sensor and Flood Detector and 470-12 Water Sensor, the FP280 detects water when approximately 1/4 inch (6.4 mm) of non-distilled water contacts the sensing probe. Featuring a 16-foot (approximately 5-meter) two-conductor cable, integrated end-of-line resistor, and compact white housing, the FP280 allows the sensing element to be positioned near floors, plumbing fixtures, water heaters, sump pumps, and other locations vulnerable to water accumulation. The probe measures approximately 1.5 inches long, 1 inch wide, and 0.38 inch high and supports wall or floor mounting using the included double-sided adhesive tape or mounting screw. When connected to a compatible wireless transmitter, the FP280 enables flood alarm reporting to supported security control panels and remote notification services. Its passive sensing design requires no separate batteries, wireless enrollment, or external power supply, making it suitable for residential basements, laundry rooms, bathrooms, kitchens, utility spaces, and commercial facilities requiring localized water leak detection.

Honeywell Home FP280 External Flood Detection Probe with 16-Foot Cable

The Honeywell Home FP280 External Flood Probe provides localized water detection for residential and commercial properties requiring early notification of leaks, flooding, and unwanted water accumulation. Manufactured by Resideo under the Honeywell Home brand, the FP280 is designed to connect to compatible Honeywell 5821 Wireless Temperature Sensor and Flood Detector and 470-12 Water Sensor equipment. The probe detects the presence of conductive water at its sensing contacts and communicates the resulting electrical condition to the connected transmitter. The transmitter then reports the flood event to a compatible security control panel or monitoring system. This arrangement allows installers to position the water sensing probe near the floor while mounting the associated wireless transmitter in a separate, accessible location, reducing the likelihood of exposing the transmitter electronics to standing water. Typical applications include basements, laundry rooms, bathrooms, kitchens, utility closets, water heater locations, sump pump areas, and commercial mechanical spaces where water leaks could damage flooring, stored materials, electrical equipment, or building infrastructure.

The FP280 incorporates a compact white sensing enclosure, permanently attached two-conductor cable, and integrated end-of-line resistor for use with compatible supervised water detection transmitters. The manufacturer specifies physical dimensions of approximately 1.5 inches (38 mm) long, 1 inch (25.4 mm) wide, and 0.38 inch (9.5 mm) high, allowing the probe to fit into confined locations near plumbing connections and water-sensitive equipment. Its attached cable measures approximately 16 feet (5 meters), providing flexibility when locating the transmitter away from the potential flooding area. The manufacturer documents a 2.2-megohm end-of-line resistor in the flood sensing arrangement, allowing supported transmitters to supervise the external sensing circuit. The probe uses non-polarized wiring, simplifying connection to the designated sensor terminals on compatible equipment. When used with the Honeywell 5821, the flood detection function is designed to respond when approximately 1/4 inch (6.4 mm) of water covers the probe contacts. Unlike an independent electronic flood detector, the FP280 contains no internal wireless radio, alarm sounder, batteries, or user-programmable electronics. Its sensing operation depends on the connected transmitter and the electrical conductivity of the detected water.

For wireless security and environmental monitoring applications, the Honeywell FP280 functions as the external sensing component of a compatible flood detection system. When conductive water reaches the probe contacts, the electrical characteristics of the sensing circuit change, allowing the connected transmitter to recognize a flood condition. With the Honeywell 5821 Wireless Temperature Sensor and Flood Detector, this condition can be reported through a compatible 5800 Series wireless receiver and security control panel. The 5821 operates at 345 MHz and supports configurations for flood detection alone or simultaneous flood and low-temperature monitoring. In combined operation, the transmitter can monitor water at the FP280 probe while using its internal temperature sensor to detect ambient temperatures below approximately 45 F (7 C), with separate alarm zone assignments as specified by the manufacturer. When integrated with supported Honeywell Total Connect or Resideo remote services, the associated security system may provide email, text, or application notifications of detected flooding, depending on system configuration and service availability. The FP280 is also documented for use with the Honeywell 470-12 Water Sensor, and compatible third-party transmitters such as the Inovonics EN1751 may support the probe in specifically approved configurations. The FP280 itself does not provide wireless communication or remote notifications without the required connected equipment.

Installation of the Honeywell Home FP280 water sensing probe involves selecting a location where leaking or accumulating water is likely to reach the sensing contacts before significant damage occurs. The probe supports floor-level or wall-mounted placement using the supplied double-sided adhesive tape or mounting screw, allowing installers to position it near water heaters, washing machines, plumbing fixtures, condensate drains, sump pumps, or other potential leak sources. The attached approximately 16-foot cable connects directly to the external sensor terminals of the compatible transmitter, with no polarity requirement for the two probe conductors. For Honeywell 5821 installations, the manufacturer specifies connecting the probe wiring before installing the transmitter battery and then configuring the appropriate flood detection operating mode. The 5821 installation documentation identifies Loop 3 for flood sensing, with additional loop programming available when simultaneous low-temperature monitoring is required. Once the transmitter is enrolled with the compatible security panel, technicians verify wireless signal strength, confirm proper flood detection operation, and test the system's alarm restoration and supervisory reporting according to the manufacturer instructions. The probe should remain accessible for periodic inspection and functional testing, and its sensing contacts must not be painted or obstructed. The FP280 differs from the Honeywell 470PB external water probe by incorporating an extended factory-attached cable and integrated termination resistor, simplifying installation where the transmitter must be mounted away from the sensing location. Combining compact construction, integrated circuit supervision, flexible mounting, and compatibility with established Honeywell environmental monitoring systems, the FP280 provides a practical accessory for detecting water accumulation before it causes extensive property damage.