ADEMCO 5821 Flood Detector with Temperature Sensing Option
The ADEMCO 5821 Flood Detector & Temperature Sensor is a wireless transmitter used with Honeywell's alarm
systems that support 5800 series devices. The 5821 can be configured to operate,
as a stand-alone temperature sensor and/or,
as either a Flood Detector or Remote Temperature Sensor.
The 5821 in combination with the FP280 or ADEMCO 470PB probe can be used to sense floods in basements
and other areas where there is a possibility of flooding.
temperature limit is exceeded or when a flood is detected. Temperature monitoring and flood detection is
dependent on the operating mode selected. Refer to Table 1 for applicable operating modes.
The 5821 in combination with the ADEMCO T280R temperature probe is ideal for monitoring refrigerators and
freezers in restaurants, kitchens and warehouses where food storage is a concern.
A separate 5821 is required for each external probe being used.
Flood detection is monitored remotely using the FP280 or ADEMCO 470PB probe with the supplied resistor.
Room temperature is monitored at the device using the 5821's internal sensor.
Refrigerator or Freezer temperature is monitored remotely using the ADEMCO T280R temperature probe.
In refrigerator or freezer applications, when the temperature increases past the high threshold limit and a delay of
greater than 30 minutes passes, an alarm is triggered. This preset delay offers greater reliability against false alarms,
especially due to open refrigerator or freezer doors.
The 5821 tamper supervision feature (Loop 4) causes a trouble signal to be sent to the control if the unit's cover is
removed from the base or if an external probe is used and the wire is cut (open) or the probe is shorted.
switch is also used to program the unit's serial number and loop assignments to the control panel.
Wireless Transmission Path Test
Before permanently installing the detector, determine that there is good signal reception from the proposed location.
Perform the test procedure described in TESTING THE DETECTOR section. Once confirmed, mount the detector.
MOUNTING THE DETECTOR
• Mount the 5821 in any direction, on a wall or
ceiling, within the protection area.
• We recommend that the mounting plate be used.
• Avoid mounting the detector near heat generating
devices (e.g. ovens, heat vents, furnaces, boilers)
or to a metal cabinet or surface.
When used in-conjunction with:
- FP280 flood sensor probe, with built-in wire
approx. 16 feet long (5 meters) ready to tie into
- ADEMCO 470PB flood sensor probe, use no
more than 48 inches of wire from the 5821 to the
flood sensor and connect the termination resistor
across the probes terminals.
- ADEMCO T280R temperature probe, use the
shortest wire possible (less than 96 inches) to
improve the signal integrity.
IMPORTANT: DO NOT remove the circuit board from the back case plastic.
External Probe Wiring Connections (If used)
1. With the battery not inserted, connect the wires to the unit's sensor terminals; see below.
2. Install the battery.
The 5821 will send an alarm when the preset