Heiman Carbon Monoxide Detectors, Digital Display Low-Level CO Alarm 3 Pack

The HEIMAN Carbon Monoxide Detector 3 Pack provides residential monitoring designed to track CO emissions from household sources such as furnaces, water heaters, gas stoves, fireplaces, clothes dryers, portable generators, and vehicle exhaust. Certified to UL 2034 5th Edition standards, these units give households dedicated safety coverage across multiple living spaces without complicated setup.

Each detector features a digital LCD screen that displays live readings starting at 20ppm, allowing you to check ambient levels at a glance. Safety monitoring is handled through a tiered notification system: a low-level early warning alerts you at 30ppm for slow buildups, while an 85dB alarm sounds during dangerous conditions. If an event occurs while you are away, the unit includes a 12-hour alarm memory so you are notified of missed spikes when you return.

Powered by 2 replaceable AA batteries, these standalone units do not plug into wall outlets or require home wiring. You can place them directly on a tabletop or attach them to a wall using the included hardware kit. A built-in safety lock prevents the battery compartment from closing if batteries are missing, and each unit automatically powers on after an initial 100-second warm-up. For regular maintenance, a single Test/Hush button handles weekly self-tests and lets you temporarily silence nuisance alarms for 4 minutes, low-battery alerts for 12 hours, or end-of-life chirps for 48 hours.

Keep in mind that these are strictly battery-operated devices and will require routine battery changes over their operational life whenever the low-battery warning sounds. They also do not support outlet power, so users looking for plug-in units will need to look elsewhere.

Verdict: This 3-pack is a practical choice for homeowners, renters, and travelers who need certified, portable carbon monoxide detection with clear digital readouts. It is well suited for anyone wanting flexible tabletop or wall placement across several rooms without dealing with electrical wiring.

• Safety Standard: UL 2034 5th Edition Certified
• Power Source: 2 replaceable AA batteries per unit
• Alarm Volume: 85dB
• Display: Digital LCD (reads from 20ppm)
• Early Warning Level: 30ppm
• Alarm Memory: 12-hour memory
• Dimensions: 4.09 inches L x 2.89 inches H x 1.43 inches W
• Weight: 4.37 oz
• Warm-up Time: 100 seconds
• Package Quantity: 3 units

A great fit if you:

• Need multi-room carbon monoxide coverage for areas near fuel-burning appliances like furnaces and water heaters.
• Want visible, real-time CO level readouts on an LCD screen starting at 20ppm.
• Prefer freestanding or wall-mounted alarms that do not require an electrical outlet or professional wiring.
• Want portable detectors for trips to hotels, vacation rentals, cabins, or RVs.

Consider something else if you:

• Prefer hardwired or plug-in alarms that run directly on household electrical power.
• Do not want to manage periodic AA battery replacements.

What kind of batteries does this alarm use?
Each detector operates on 2 replaceable AA batteries and does not connect to wall outlets or household wiring.

How does the alarm notify you of low carbon monoxide levels?
The LCD screen displays real-time readings starting at 20ppm, and the system delivers an early warning alert at 30ppm for gradual buildups.

What does the Test/Hush button do?
The button runs weekly self-tests and can silence false alarms for 4 minutes, low-battery chirps for 12 hours, and end-of-life alerts for 48 hours without stopping active CO monitoring.

Can this detector be placed on a shelf or tabletop?
Yes. You can set it directly on any flat surface or mount it to a wall using the provided hardware kit.