1. Product Overview
The First Alert BRK SC-9120B is a hardwired smoke and carbon monoxide (CO) detector designed to provide continuous 24/7 protection for your home. This dual-sensor alarm combines an ionization smoke sensor for detecting fast-flaming fires and an electrochemical carbon monoxide sensor for accurate CO detection. It features a 120V AC power source with a 9V alkaline battery backup, ensuring operation even during power outages.
Figure 1.1: Front view of the First Alert BRK SC-9120B Combination Smoke and CO Detector.
Key features include a single test/silence button, separate latching alarm indicators for smoke and CO, and a silencing technology that can temporarily quiet low-battery chirps for up to eight hours or nuisance alarms. The unit also provides an audible end-of-life signal, indicating when it's time for replacement.
Figure 1.2: The First Alert BRK SC-9120B detector installed on a ceiling, blending with home decor.
2. Important Safety Information
Please read and understand all instructions before installing and operating your detector. Failure to follow these instructions may result in property damage, injury, or death.
- This unit is designed for indoor use only.
- Ensure the detector is connected to a 120V AC power supply.
- A 9V alkaline battery is required for backup power and must be installed for proper operation. The battery is not included with the unit.
- Regularly test your detector as described in the Operating Instructions section.
- Do not paint the detector. Paint can clog the sensing chambers and prevent the alarm from operating properly.
- The detector has an end-of-life signal. When this signal sounds, the unit must be replaced immediately.
3. Package Contents
Verify that all items are present in your package:
- First Alert SC-9120B Combination Smoke and CO Detector Unit
- Mounting Bracket
- Quick Connect Wiring Harness
- Installation Hardware (screws, wall anchors)
- User Manual
Note: A 9V alkaline battery is required for battery backup functionality and is not included in the package. Please purchase separately.
4. Setup and Installation
The First Alert BRK SC-9120B is designed for easy installation, featuring a universal mount bracket and keyhole slots that simplify the process.
4.1 Choosing a Location
For optimal protection, install smoke alarms on every level of your home, inside bedrooms, and outside sleeping areas. Carbon monoxide alarms should be installed on every level of your home and in sleeping areas. Avoid installing near vents, fans, or in extremely dusty, dirty, or humid areas.
4.2 Wiring Instructions
This detector is hardwired and connects to your home's 120V AC electrical system. A large opening in the mounting bracket provides easy access to wiring. Use the quick connect wiring harness for secure connections.
Figure 4.1: Rear view of the detector illustrating the wiring harness connection points (Black, Orange, White).
Wiring Connections:
- Black Wire: Connect to the hot (live) wire from the electrical box.
- White Wire: Connect to the neutral wire from the electrical box.
- Orange Wire: (Interconnect) Connect to the interconnect wire from other compatible First Alert/BRK alarms for synchronized alarming.
Ensure all power to the circuit is turned off at the main fuse or circuit breaker box before beginning installation.
4.3 Battery Installation
A 9V alkaline battery is required for backup power. The battery compartment is located on the side of the unit, allowing for installation and removal even when the unit is mounted.
Figure 4.2: Side view of the detector with the 9V battery compartment open.
Insert the 9V battery, ensuring correct polarity (+/-). A battery pull tab keeps the battery fresh until the unit is installed and activated. Once the battery is installed and the unit is connected to AC power, the detector is ready for operation.
5. Operating Instructions
Your First Alert BRK SC-9120B detector is designed for simple operation and clear indication of alarm conditions.
5.1 Test/Silence Button
The large test/silence button on the front of the unit serves two primary functions:
- Testing: Press and hold the button to test the alarm's functionality. The alarm will sound, indicating that the smoke and CO sensors are working. Test the alarm weekly.
- Silencing: In case of a nuisance alarm (e.g., from cooking smoke), press the button to temporarily silence the alarm. The alarm will reset after a few minutes if the smoke or CO levels return to normal.
- Low Battery Chirp Silence: If the unit chirps due to a low battery, pressing the button can silence the chirp for up to eight hours, allowing time to replace the battery.
5.2 Alarm Indicators
The detector features separate latching alarm indicators for smoke and carbon monoxide. These indicators will illuminate and remain on to show which unit initiated an alarm, even after the alarm has stopped sounding. This helps in identifying the source of the alert.
6. Maintenance
Regular maintenance ensures the continued reliable operation of your detector.
6.1 Battery Replacement
Replace the 9V alkaline battery at least once a year, or immediately when the low battery chirp sounds (unless silenced temporarily). Use only recommended replacement batteries.
6.2 Cleaning Your Detector
Dust and debris can accumulate on the detector, potentially affecting its performance. Clean your detector at least once a month:
- Gently vacuum the exterior of the alarm using the soft brush attachment of your vacuum cleaner.
- Do not use cleaning solvents or sprays directly on the unit.
6.3 End-of-Life Signal
The detector is designed with an end-of-life signal that provides an audible notification when the unit needs to be replaced. This typically occurs after 10 years of operation. When you hear this signal, replace the detector immediately.
7. Troubleshooting
If your detector is not functioning as expected, refer to the following common issues and solutions:
| Problem | Possible Cause | Solution |
|---|---|---|
| Alarm sounds frequently without apparent reason. | Nuisance alarm (cooking smoke, steam), dust accumulation, improper placement. | Press the Test/Silence button. Clean the detector. Relocate if consistently triggered by non-emergency events. |
| Unit chirps periodically. | Low battery. | Replace the 9V battery. You can silence the chirp for up to 8 hours by pressing the Test/Silence button. |
| Alarm does not sound during test. | No power (AC or battery), faulty unit. | Check AC power connection. Ensure 9V battery is installed correctly. If issues persist, replace the unit. |
| End-of-life signal sounds. | Detector has reached its operational lifespan. | Replace the entire detector unit immediately. |
| Only one interconnected alarm sounds. | Interconnect wiring issue, or the initiating unit's latching alarm indicator is the only one active. | Check interconnect wiring. Identify the initiating unit by its latching alarm indicator. |
8. Specifications
| Feature | Detail |
|---|---|
| Brand | First Alert |
| Model Number | SC9120B |
| Power Source | Hardwired (120V AC) with 9V Battery Backup |
| Battery Type | 9V Alkaline (not included) |
| Sensor Type | Ionization (Smoke), Electrochemical (CO) |
| Alarm Type | Audible |
| Product Dimensions | 2.25"D x 5.59"W x 5.69"H |
| Item Weight | 10.4 ounces |
| Material | Plastic |
| Usage | Indoor use only |
| Manufacturer | BRK Brands |
9. Warranty and Support
The First Alert BRK SC-9120B Combination Smoke and Carbon Monoxide Detector comes with a 10-year limited warranty. This warranty covers defects in material and workmanship under normal use and service.
For warranty claims, technical support, or further assistance, please refer to the contact information provided in the documentation included with your product or visit the official First Alert website.
