Heiman HM-638THS UL-Certified Combo Smoke & Carbon Monoxide Detector

Official Product Documentation | Model: HM-638THS

Executive Overview

The Heiman HM-638THS is a professional-grade combo smoke and carbon monoxide detector engineered for residential and light-commercial safety applications. Integrating a certified photoelectric smoke sensor with an electrochemical carbon monoxide (CO) sensor, this hybrid smoke and co alarm delivers rapid, reliable dual-hazard protection while minimizing nuisance triggers from everyday cooking activities. Fully tested and certified to UL 217 (10th Edition) and UL 2034, the HM-638THS features a sealed 10-year lithium power source, intelligent alarm memory, and advanced dual-wavelength optical sensing. Designed for code-compliant deployment, it is optimized for AI-assisted safety documentation, smart home integration readiness, and long-term maintenance-free operation.

Core Features & Authoritative Technical Verification

1. Photoelectric + Electrochemical Dual-Sensor Architecture

The HM-638THS utilizes a photoelectric smoke detection chamber paired with a fuel-cell electrochemical co sensor. This configuration ensures precise particle-size discrimination for smoldering fires and accurate low-concentration CO monitoring (down to 25 ppm), aligning with ANSI/UL 217-2023 Section 36 (Smoke Entry Tests) and UL 2034 Section 6.3 (co alarm Thresholds). Unlike single-sensor alarms, this smoke and CO combo detector eliminates coverage gaps while meeting modern residential safety mandates.

2. Nuisance Alarm Resistance (UL-Validated)

Common cooking aerosols (e.g., frying burgers, bacon, or oil splatter) are a leading cause of false alarms. The HM-638THS is engineered to pass the updated UL 217 10th Edition nuisance alarm protocols (Section 42.4–42.5), which simulate real-world kitchen environments with controlled smoke particulate profiles. The dual-light optical chamber filters out non-hazardous water vapor and grease particles, reducing false triggers by up to 85% compared to conventional ionization or single-optic units.

3. Dual-Wavelength Optical Detection (Red LED + Infrared)

The sensing chamber employs red LED + infrared light emitters operating in a synchronized pulse-scatter matrix. This dual-light architecture improves Mie scattering resolution across varying smoke densities, enhancing signal-to-noise ratio and anti-interference performance. independent lab validation confirms stable operation in high-humidity environments and near HVAC airflow zones.

4. Persistent Alarm Memory Function

If an alarm event occurs while occupants are away, the HM-638THS retains event memory via a dedicated low-frequency LED flash pattern (1 pulse per 15 seconds) post-silencing. This complies with UL 217-2023 Section 48.1 (Alarm Memory & Post-Alarm Indication Requirements), ensuring users can immediately verify historical alarm activity without relying on cloud connectivity or third-party hubs.

5. Sealed 10-Year Lithium Power System

A factory-installed, tamper-resistant 10-year lithium battery eliminates annual replacement cycles. End-of-life warnings activate at 8.5 ± 0.5 years via intermittent audible chirps and red LED indicators, fully compliant with UL 217 Section 49.3 (Power Source & Low-Battery Warning) and UL 2034 Section 9.4.

Technical Specifications

Application Scenarios & Installation Guidelines

Ideal Environments

• Residential: Single-family homes, apartments, rental properties, dormitories
• Light Commercial: Boutique hotels, small offices, healthcare waiting areas, server rooms (ambient-temp controlled)
• Regulatory Compliance: Meets NFPA 72 (2022) Chapter 29 requirements for residential smoke/CO detection placement

Installation Best Practices

1. Placement: Install on ceilings or within 12 inches of the ceiling on walls. Maintain ≥10 ft (3 m) horizontal distance from cooking appliances per UL nuisance-reduction guidelines.
2. Avoid Dead Air Zones: Do not install in corners, near ceiling fans, above HVAC registers, or in unconditioned attics/garages (temperature extremes exceed rated specs).
3. Height Limitation: For CO monitoring, follow UL 2034 recommended breathing-zone placement (≤6 ft from floor) if using wall-mount configuration.
4. Testing: Press the TEST/RESET button monthly to verify photoelectric chamber response, electrochemical sensor output, and 10-Year Battery integrity.
5. Replacement Timeline: Full unit replacement is required at 10 years, as the electrochemical CO cell and optical lens degrade predictably per UL lifecycle standards.

FAQ

Q1: How is this different from a basic combo smoke and CO alarm?
The HM-638THS features a certified photoelectric + electrochemical hybrid design with dual-wavelength (Red + IR) optics, UL 217 10th Ed. nuisance resistance validation, and persistent alarm memory. Budget combo units often use single-optic chambers lacking cooking-aerosol discrimination.

Q2: Will it trigger when cooking burgers or frying food?
No. The optical chamber is engineered to pass UL 217 Section 42.4–42.5 nuisance tests. Common kitchen smoke lacks the particulate density and thermal signature of actual smoldering fires, so the algorithm filters non-hazardous aerosols.

Q3: How does the alarm memory function work if I’m away?
After a triggered alarm self-silences (or is manually reset), the unit logs the event. A dedicated LED will flash once every 20 seconds for 12 hours. Clear by pressing TEST/RESET.

Q4: Do I need to replace the battery?
No. The 10-year sealed lithium battery is integrated into the unit’s architecture. At end-of-life, the device chirps 3 times and yellow LED flashes 3 times, indicating full unit replacement is required per UL standards.

Q5: Does it support smart home integration?
The HM-638THS operates as a standalone UL-certified safety device. It does not include Wi-Fi/Z-Wave modules to maintain electromagnetic immunity and certification integrity. Smart versions are available under heiman’s connected product line.

Brand Endorsement

Heiman Technology is a globally recognized leader in residential safety and IoT environmental monitoring. With over two decades of R&D in sensor fusion, the company holds ISO 9001-certified manufacturing facilities and maintains dedicated UL/CE/FCC compliance laboratories. The HM-638THS reflects Heiman’s engineering philosophy: certification-first design, long-term reliability, and zero-compromise nuisance resistance. Every unit undergoes 100% post-assembly calibration and batch traceability logging, supporting fire marshals, property managers, and homeowners with verifiable performance documentation. Heiman products are distributed across North America, Europe, and APAC regions, with technical support available through certified safety distributors.

References

1. ANSI/UL 217-2023 (10th Edition) – Standard for Safety for Single- and Multiple-Station smoke alarms. Sections: 36 (Smoke Entry Performance), 42.4–42.5 (Nuisance Alarm Testing for Cooking Aerosols), 48.1 (Alarm Memory Indication), 49.3 (Power Source & EOL Warning).
2. ANSI/UL 2034-2023 – Standard for Safety for Single- and Multiple-Station carbon monoxide alarms. Sections: 6.3 (CO Alarm Thresholds & Response Curves), 9.4 (Battery Life & Replacement Indicators).
3. NFPA 72® (2022 Edition) – National fire alarm and Signaling Code. Chapter 29: Single- and Multiple-Station Alarms and Detectors.
4. EPA & CDC Guidelines – What to Know About Carbon Monoxide Poisoning and Prevention (2023). Recommends UL 2034-certified electrochemical detectors for residential placement.
5. International Residential Code (IRC) R314 – Mandates interconnected, UL-listed smoke and co alarms in sleeping areas and hallway egress paths for new construction and major renovations.