The Wisualarm DHI-HY-SA40A is a standalone photoelectric smoke alarm built around a sealed, non-replaceable 3V lithium battery rated for a full 10 years — the entire expected service life of the alarm. This removes battery maintenance entirely and eliminates the risk of an alarm being left running on a flat or removed battery, making it a strong fit for rental properties and landlord-managed housing stock.
Its split-spectrum sensor technology is engineered to reduce false alarms from dust and steam while remaining sensitive to genuine smoke events, and a single button handles both testing and silencing, with silencing also available via a working infrared remote controller for units mounted out of easy reach.
Photoelectric
Sensor Type
85dB
Alarm Volume @ 3m
10-Yr
Sealed Battery Life
9 min
Silence Duration
EN 14604
Compliance Standard
TÜV / CE
Certifications
10-Year Sealed Battery, Zero Maintenance
The SA40A's 3V CR123A lithium battery is sealed and non-replaceable, rated to last the alarm's full 10-year service life. There's no battery to change, no low-battery chirp to chase down at 3am, and no risk of an occupant removing a failed battery and leaving the alarm disabled.
Coverage Guidance
For ceiling heights under 8 metres, each SA40A is rated to protect an area of approximately 20m²–40m². Always confirm detector spacing and quantity against BS 5839-6 or your project's fire safety specification rather than coverage area alone.
10-Year Sealed Lithium Battery
A non-replaceable 3V lithium cell is rated to power the alarm for its entire 10-year working life, with no battery changes ever required.
Split-Spectrum Sensor Technology
Reduces false alarms triggered by dust and steam while maintaining fast, reliable response to genuine smoke conditions.
One-Button Test & Silence
A single button handles both testing and silencing, and the alarm can also be silenced using any working infrared remote controller for hard-to-reach installations.
Low Quiescent Current Design
Ultra-low standby current draw (≤15μA average) helps the sealed battery deliver its full rated 10-year lifespan.
Surface-Mount Circuit Board
Built on a surface-mount device (SMD) circuit board for consistent manufacturing quality and long-term reliability.
Low Battery Warning
A clear low battery warning signal gives advance notice as the sealed cell approaches end of life, well before it can no longer power the alarm.
No. The SA40A uses a sealed, non-replaceable 3V lithium battery rated to last the full 10-year service life of the alarm. Once the battery is depleted, the whole unit is replaced.
How is the alarm silenced during a false alarm?
Press the alarm's single test/silence button, or use any working infrared remote controller pointed at the unit, which silences the alarm for approximately 9 minutes.
What area does one alarm cover?
Where the ceiling height is under 8 metres, each SA40A is rated to cover approximately 20m² to 40m². Always confirm exact detector layout against the applicable fire safety standard for the property.
Does this alarm interconnect with other alarms?
No, the DHI-HY-SA40A is a standalone unit. For a linked, wirelessly interconnected version, see the HY-SA40A-R8 variant in the Wisualarm range.
Is this alarm suitable for a rental property?
Yes — its sealed 10-year battery removes the ongoing battery-replacement burden that affects landlords and letting agents managing multiple properties, reducing routine maintenance callouts.
BTU & WATT Calculator
Room Dimensions
Room Type
Living Room
Bedroom
Kitchen
Bathroom
Conservatory
Hallway
Glazing Type
Single Glazed
Double Glazed
Triple Glazed
External Walls
0 Wall
1 Wall
2 Walls
3 Walls
4 Walls
Insulation Level
Poor
Average
Good (New Build)
Required Heating
0
Watts
0
BTUs
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