Flood & Temperature Sensors — Specs, Brands & Hong Kong Installation
Water-leak probes and temperature sensors for kitchens, plant rooms, and compact IT cupboards.

What this sensor does
Environmental sensors protect against water damage and temperature extremes — AC drip trays, hidden pipe joints, and overheating DVR cupboards are typical Hong Kong failure points that an intrusion PIR will never see.
Honeywell 5821 is the wireless 5800 flood/temperature device. On Bosch panels we wire a zone water probe at the lowest point of the room or plant area.
- Floor-level water probe
- High / low temperature reporting
- Freeze warning for exposed pipes
- Same keypad as intrusion zones
Sensor brands & official websites
Brand names with manufacturer product pages. We specify models after a site survey and install them in Hong Kong.
Brand
Honeywell / Resideo
Wireless 5800-series PIRs, contacts, glass-break, smoke, shock, and flood sensors for VISTA and ProSeries panels.
Brand
Bosch
Blue Line and TriTech motion, magnetic contacts, glass-break, smoke, seismic, and zone water probes for G-series panels.
Brand comparison
Side-by-side specs for models Swan CCTV supplies and installs.
| Spec | Honeywell5821 Wireless Temperature / Flood | BoschZone Water / Flood Probe |
|---|---|---|
| Type | Wireless flood + temperature | Wired water / flood probe |
| Coverage / range | — | Lowest point near AC drip trays or pipe joints |
| Power | Lithium (supervised) | Panel zone voltage |
| Best for | Kitchens, bathrooms, plant rooms, and server cupboards | Plant rooms, kitchens, and meter cupboards |
Models we install
Open any model for full specifications, datasheets, and Hong Kong installation notes.

5821 Wireless Temperature / Flood
Wireless environmental sensor for water leaks and high/low temperature alerts.
- Type
- Wireless flood + temperature
- Flood
- External probe / contact input
- Temperature
- High / low threshold reporting
- Battery
- Lithium (supervised)

Zone Water / Flood Probe
Wired water probe on a Bosch zone for plant rooms, kitchens, and leak-prone interiors.
- Type
- Wired water / flood probe
- Loop
- NO/NC with EOL on Bosch zone
- Detection
- Conductive water contact at floor level
- Voltage
- Panel zone voltage
Hong Kong / local context
Place probes under window-unit A/C drip trays and at bathroom/kitchen pipe entries — the usual leak sources in older blocks.
Server / NVR cupboards in meter rooms need overheat as well as flood — we often quote both on one 5821 or a pair of Bosch zones.
Other sensor types
Complete coverage usually mixes several detector types on one panel.
PIR Motion Sensors
Passive infrared and dual-technology motion detectors for rooms, corridors, and shop floors.
View modelsDoor & Window Contacts
Magnetic reed contacts for metal gates, aluminium windows, shutters, and internal doors.
View modelsGlass Break Detectors
Acoustic detectors that listen for breaking glass across a room — useful for shopfronts and glazed offices.
View modelsSmoke & Heat Detectors
Photoelectric smoke and heat detectors that report fire warning on the same alarm panel as intrusion.
View modelsVibration & Shock Sensors
Shock and seismic detectors for windows, walls, safes, and forced-entry on solid structures.
View models