The Wisualarm DHI-HY-GC20A is a standalone carbon monoxide alarm built to continuously monitor CO concentration in the home using a high-performance Figaro electrochemical sensor. It responds quickly and accurately to rising CO levels while maintaining stable, low-false-alarm performance, and is suitable for homes, restaurants, hotels and any other space that needs carbon monoxide detection.
An easy-to-read three separate LED indicators for alarm, fault and power status, so occupants can see the alarm's condition at a glance. Power comes from a replaceable 3V CR123A lithium battery rated for up to 10 years, and the unit supports low battery warning, one-click silence and self-test functions from a single control button.
Electrochemical
Figaro CO Sensor
>85dB
Alarm Volume @ 3m
10-Yr
Battery Life
LED
CO Display
Standalone
Operation
EN 50291-1
Compliance Standard
UK Legal Requirement — Carbon Monoxide Alarms
Under the Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022, private sector landlords in England must install a CO alarm in every room with a fixed combustion appliance (excluding gas cookers); social landlords have been subject to the same requirement since 1 February 2023. The DHI-HY-GC20A, certified to EN 50291-1:2018, meets the technical standard required for compliance. Scottish properties are subject to separate requirements under the Housing (Scotland) Act 2006.
Standalone Unit — No Interconnect
The GC20A operates as an independent, standalone alarm and does not interconnect wirelessly with other CO alarms. Where a property needs multiple CO alarms linked together, the wireless interconnected Wisualarm CO alarm range (such as the GC20A-R8) is the appropriate choice instead.
High-Performance Figaro CO Sensor
A Figaro electrochemical sensor delivers accurate detection of carbon monoxide leakage and responds quickly to rising concentrations.
10-Year Replaceable Battery
Powered by a replaceable 3V CR123A lithium battery with a rated life of up to 10 years, combining long standby time with low power consumption.
Three-LED Status Indication
Separate red, yellow and green LED indicators clearly display alarm, fault and power status respectively, so the device's condition is obvious at a glance.
One-Click Silence & Self-Test
Supports low battery warning, one-click silence, and self-test from a single control, simplifying routine checks and false-alarm management.
Compact Wall-Mounted Design
A delicate, compact enclosure designed for simple and convenient wall-mounted installation in any room requiring CO detection.
Product Identity
Model number
DHI-HY-GC20A
Brand
Wisualarm (by Dahua)
Operation
Standalone
Detection
Collection type
Carbon Monoxide (CO)
Sensor type
Electrochemical (Figaro)
Alarm response threshold
50ppm: 60–90 min | 100ppm: 10–40 min | 300ppm: <3 min
Power
Power source
3V CR123A lithium battery (replaceable)
Battery life
10 years
Monitoring current
≤20μA
Alarm current
≤10mA
Alarm Output
Alarm volume
Over 85dB(A) at 3 metres
Alarm mode
Visual and audible alarm
Silencing
Yes — approx. 45 seconds
Indicators
Alarm
Red LED
Fault
Yellow LED
Power
Green LED
Physical & Environmental
Dimensions
116.4mm × 71.7mm × 28.3mm
Weight
125 g
Colour / material
White, PC + ABS
Installation
Wall mount
Operating environment
Indoor use only
Operating temperature
-10°C to +40°C
Operating humidity
≤95% RH, non-condensing
Certification
Certifications
TÜV and CE listed
Compliance standard
EN 50291-1:2018
Where should a carbon monoxide alarm be installed?
Fit a CO alarm in every room with a fixed combustion appliance — a gas or oil boiler, gas fire, log burner, open fireplace, wood-burning stove or pellet stove — typically within 1–3 metres of the appliance on the same level, plus each sleeping level of the property.
Is a CO alarm a legal requirement?
Yes. Under the Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022, private and social landlords in England must fit a CO alarm in any room with a fixed combustion appliance (excluding gas cookers). Scottish properties follow separate requirements under the Housing (Scotland) Act 2006.
How long does the battery last?
The GC20A's replaceable 3V CR123A lithium battery is rated for up to 10 years of service, with a low battery warning to give advance notice before replacement is needed.
Can this alarm be interconnected with other CO alarms?
No, the DHI-HY-GC20A is a standalone device. For a wirelessly interconnected CO alarm that links with other WisuLink devices, look to the Wisualarm GC20A-R8 or GC30A-R8 models instead.
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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