The Dahua DHI-HY-SA21A-W2 is a battery-powered wireless smoke alarm designed to deliver fast, reliable smoke detection for residential environments. Featuring advanced split-spectrum photoelectric sensor technology, it minimizes false alarms while providing timely alerts via loud siren and real-time DMSS app notifications.
Key Features
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Photoelectric Split-Spectrum Sensor - for early and accurate smoke detection
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Loud 85–90 dB Alarm - at 3 meters with both visual and audible notifications
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Battery-Powered - with 3-year lithium battery (replaceable CR123A)
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Smart LED Indicators - for standby, alarm, fault, and low battery states
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DMSS App Integration - for real-time remote smoke alerts
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Single Button Test/Silence Function - for user convenience
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Surface-Mount Device (SMD) Circuit Board - for stable performance
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Two-Way Encrypted Wireless Communication - with AES128 & frequency hopping
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Easy Ceiling Mount Installation — no wiring required
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Long Wireless Range - Up to 1000m (open space)
Perfect For:
- Residential homes and villas
- Apartments and condominiums
- Small retail shops
- Airbnbs or rental units
- Utility or storage rooms
- Small office environments
Install Tips
- Mount the device on the ceiling in the center of rooms for optimal smoke detection coverage.
- Avoid installing near fans, vents, or cooking appliances to reduce false alarms.
- Ideal mounting height is on flat ceilings—do not place on sloped or wall surfaces.
- Replace battery after 3 years or when low battery warning LED blinks red.
- Pair the alarm with the DMSS app for remote notifications and enhanced monitoring.
- Press and hold the button for testing functionality or silencing during false triggers.
Downloads
Quick-Read Specs Card
Feature |
Details |
Sensor Type |
Photoelectric |
Alarm Volume |
85–90dB @ 3 m |
Alarm Types |
Smoke, fault, low battery |
LED Indicators |
Red and green (multi-state) |
Battery Life |
Up to 3 years (CR123A lithium) |
Wireless Frequency |
433.1–434.6 MHz |
Communication Range |
Up to 1000 m (open space) |
Mobile App |
DMSS (real-time alert support) |
Installation |
Ceiling mount |
Operating Temp |
-10°C to +55°C |
Humidity |
≤ 95% RH (non-condensing) |
Certifications |
TÜV, CE, EN 14604:2005+AC:2008 |
Material |
ABS casing, white |
Extra Info
Advanced Smoke Sensing
The DHI-HY-SA21A-W2 uses photoelectric detection technology to better sense slow-burning, smoldering fires, which are typically harder to detect. This increases the chances of early warning in typical residential and light commercial environments.
Wireless Communication & Reliability
The alarm operates on the 433 MHz frequency range with AES128 encryption, and it supports two-way communication with frequency hopping. This helps prevent signal interference and ensures reliable, long-range connectivity—up to 1000 meters in open spaces.
Real-Time Mobile Alerts
Integration with the DMSS app means users are notified instantly when smoke is detected—even if they're not home. This is crucial for remote property management or when protecting vulnerable residents.
Built-In Visual Indicators
Multicolor LED indicators let users know the device’s status at all times—from standby mode to low battery or alarm conditions—without needing to guess.
Test & Silence Button
With a single press, users can perform a routine test or silence the alarm for approximately 12 minutes—handy for false alarms caused by dust or cooking smoke.
Q&A
Q: Can this device send alerts to my phone?
A: Yes, it connects to the DMSS app for real-time push notifications.
Q: How loud is the smoke alarm siren?
A: It produces an audible alarm of 85–90 decibels at 3 meters—loud enough to wake sleeping occupants.
Q: How long does the battery last?
A: The included 3V CR123A battery can last up to 3 years under normal usage.
Q: Can I silence false alarms?
A: Yes, pressing the button will silence the alarm for about 12 minutes.
Q: Does it work with other brands' alarm systems?
A: This model is a standalone wireless smoke alarm, and integration depends on the system used. It works natively with Dahua’s DMSS app.
Q: What does the LED indicator mean?
A: A green flash every minute means standby; red flashes indicate alarm, fault, or low battery conditions.
Q: Is the alarm suitable for kitchens?
A: While it can be used in kitchens, placement should avoid areas near stovetops or vents to reduce false alarms.
Q: How far apart should I install multiple alarms?
A: Each unit covers around 20–40 m². For larger homes or spaces, multiple units should be spaced to ensure full coverage.