Heiman HM-638PHM-AC Hardwired Interconnected Smoke Detector

UL 217 (10th Edition) Certified | AC Powered photoelectric alarm with 10-Year Backup Battery

Product Overview

The heiman HM-638PHM-AC is a professional-grade, AC Hardwired Interconnected Smoke Detector engineered for reliable whole-building fire protection. Designed to meet the latest safety benchmarks, this hardwired smoke alarm features dual-optical photoelectric sensing, advanced nuisance alarm resistance, and seamless unit interconnection. Whether for new construction, multi-family dwellings, or commercial retrofits, the HM-638PHM-AC delivers rapid smoke detection, clear alarm routing, and uninterrupted operation during AC power interruptions.

Optimized for both residential and light commercial use, this interconnected smoke detector aligns with modern building codes and fire safety regulations, making it a trusted choice for contractors, property managers, and facility inspectors.

Engineered for Real-World Performance: Key Features

Hardwired Interconnect System

Up to 30 units can be connected via a dedicated interconnect wire across a single AC circuit. When any detector senses smoke, all units in the network sound simultaneously, ensuring occupants are alerted regardless of location. Each detector features a localized status LED that identifies the originating alarm source, enabling rapid response and precise fault or fire location.

Dual-Optical Photoelectric Sensing

The HM-638PHM-AC utilizes an advanced dual-wavelength photoelectric sensor combining optimized red LED and infrared light paths. This configuration increases sensitivity to slow-smoldering fires while maintaining robust immunity to environmental interference such as dust, humidity, and air turbulence.

UL 217 10th Ed Nuisance Alarm Resistance

Cooking fumes and steam have historically caused unnecessary evacuations. The HM-638PHM-AC integrates proprietary signal-processing algorithms validated against UL 217 (10th Edition) cooking smoke resistance protocols. It reliably distinguishes between hazardous combustion byproducts and transient non-hazardous aerosols (e.g., toast or light cooking smoke), significantly reducing false alarms without compromising life-safety response times.

10-Year Sealed Lithium Backup Battery

AC power failures no longer mean protection loss. A built-in 10-year lithium battery automatically engages during mains outages, providing continuous monitoring and full interconnect functionality. The sealed design eliminates maintenance, replacement costs, and tampering risks.

Alarm Memory Function

If a smoke event occurs when the premises are unoccupied, the detector stores the alarm state and indicates it via a slow-flashing LED pattern (typically 1 pulse every 20 seconds) until manually reset. This memory feature ensures property managers or residents are immediately aware of past events upon return.

Technical Specifications

Note: Specifications represent standard production data. Consult local electrical codes for exact wiring requirements.

Certification & Compliance: UL 217 (10th Edition)

The Heiman HM-638PHM-AC is independently tested and listed to UL 217 (Single and Multiple Station smoke alarms), 10th Edition. Key compliance validations include:

• Section 22.4 – Nuisance Alarm Resistance (Cooking Smoke Test): Validated under standardized pan-frying and toaster testing protocols to ensure reliable suppression of false alarms triggered by normal cooking activities.
• Section 23 – Photoelectric Response Requirements: Meets threshold sensitivity and alarm timing criteria for both smoldering (paper/cotton) and flaming (wood) fire tests, with optimized particle-size discrimination.
• Section 31 – Interconnection Performance: Verified for signal transmission integrity, alarm synchronization (< 5 seconds between first and last unit), and polarity-independent wiring compatibility across mixed-installation circuits.
• Section 44 – Power Failure & Battery Backup: Confirms automatic transition to backup power within 1 second of AC loss and continuous monitoring for ≥ 7 days under standby load.

Full certification details can be verified via the UL Online Certifications Directory under the HM-638PHM-AC listing reference. The device also meets FCC Part 15 Class B for EMI/RFI immunity, ensuring stable performance in modern wired environments.

Installation & Whole-Building Fire Protection

Designed for contractors and facility engineers, the HM-638PHM-AC simplifies compliance with NFPA 72 and International Residential Code (IRC) requirements for hardwired smoke alarm placement:

• Ideal Coverage: One unit per bedroom, outside each sleeping area, and on every level (including basements).
• Interconnect Routing: Standard 18–22 AWG solid copper wire for the interconnect line; no polarity restrictions.
• Mounting Compatibility: Fits standard 4" octagonal electrical boxes or surface-mount brackets (accessories sold separately).
• Retrofit Friendly: Direct replacement for legacy hardwired units; maintains existing wiring architecture while upgrading sensing and compliance standards.

When deployed as a unified network, the system creates a whole-home fire protection layer with synchronized auditory alerts, localized alarm tracing, and centralized event memory for post-incident review.

Why Professionals Specify the Heiman HM-638PHM-AC

• ✅ Code-Ready: Fully aligned with UL 217 (10th Ed), NFPA 72 (2025), and IRC 2021/2024 hardwired interconnect mandates.
• ✅ Lower Service Calls: Advanced dual-optical sensor + cooking smoke resistance drastically reduces nuisance dispatches.
• ✅ Zero Maintenance Battery: Sealed 10-year backup eliminates ladder work, battery stocking, and tenant complaints.
• ✅ Scalable Interconnection: Reliable performance across small homes to mid-rise residential buildings.
• ✅ Audit-Ready Documentation: CE, FCC, and UL certification packages available for permitting, insurance, and inspection submissions.

Frequently Asked Questions (FAQ)

Q: Is the HM-638PHM-AC compatible with existing 2-wire AC smoke detectors?
A: Yes. It uses a standard 3-wire configuration (Live, Neutral, Interconnect) and backward-compatible terminal labeling. Consult your wiring diagram for proper interconnect wire routing.

Q: How does it prevent false alarms from cooking smoke or steam?
A: Per UL 217 Section 22.4, the detector's firmware and dual-wavelength photoelectric chamber are calibrated to ignore particle profiles typical of light cooking, while maintaining immediate response to true combustion smoke.

Q: What happens when AC power fails?
A: The built-in 10-year lithium battery instantly engages. Alarm output, interconnect signaling, and LED memory functions remain fully operational until mains power is restored.

Q: Can I mix HM-638PHM-AC with other brands on the same interconnect loop?
A: Interconnect compatibility depends on brand-specific signaling protocols. For guaranteed synchronization, Heiman recommends using HM-638PHM-AC units across the same circuit. Cross-brand mixing may require signal compatibility verification.