For over a century, Simplex (now part of Johnson Controls) has been one of the most trusted names in fire alarm and life safety. From the iconic Simplex 4100ES and 4100U addressable panels to the legacy 4020 and 4010 series, Simplex systems protect hospitals, universities, high-rises, and government buildings across North America. When a detector fails or a NAC circuit board needs replacing, sourcing the correct Simplex fire alarm replacement parts is essential to keep your building code-compliant and your occupants safe.
At Fire Alarm Spare Parts, we carry over 2,600 Simplex parts in stock — from TrueAlarm smoke sensors and IDNet modules to signal cards and NAC extenders — so you can find exactly what you need without waiting on long factory lead times.
Popular Simplex Fire Alarm Systems We Support
Understanding which system you have is the first step toward finding the right part. Below are the most common Simplex panels and their typical replacement needs:
| Panel / System | Protocol | Common Replacement Parts |
|---|---|---|
| Simplex 4100ES | IDNet / TrueAlarm | CPU boards, TrueAlarm detectors, IDNet modules, NAC extenders |
| Simplex 4100U | IDNet | Power supplies, signal cards, annunciator boards |
| Simplex 4010 | IDNet | Motherboards, loop cards, detector bases |
| Simplex 4020 | Conventional / Mapnet II | Zone cards, relay modules, pull stations |
| Simplex 4006 / 4008 | Conventional | Zone boards, power supplies, horns |
Common Simplex Replacement Parts
Smoke Detectors & Heat Detectors
The Simplex 4098-9714 TrueAlarm photoelectric sensor and 4098-9733 heat detector are among the most frequently replaced devices. Older systems may use the 2098-9201 conventional photoelectric head or the 2098-9529 combination smoke/heat base. We stock new, refurbished, and reconditioned options for every generation.
Browse all Simplex Smoke Detectors → | Browse Simplex Heat Detectors →
Addressable Modules (IAMs, Control & Monitor)
IDNet modules are the backbone of any Simplex addressable system. The 4090-9001 supervised IAM and 4090-9002 relay IAM are the most commonly replaced. For newer 4100ES installations, the 4090-9116 and 4090-9118 TrueAlarm modules provide enhanced diagnostics.
Notification Appliances (Horns, Strobes & Speaker/Strobes)
Simplex TrueAlert notification appliances — including the 4906-9127 wall strobe and 4903-9219 horn/strobe — must meet ADA candela requirements. We carry multi-candela and single-candela models in both red and white housings.
Shop Simplex Horns & Strobes → | Shop Simplex Speakers →
Pull Stations
The Simplex 4099-9001 addressable pull station and 2099-9754 conventional pull station are standard across most installations. Dual-action and single-action variants are available.
Power Supplies, Boards & Signal Cards
Panel-level failures often trace back to a power supply or signal card. We stock the Simplex 4100-3204 power supply, 565-771 NAC extender card, and a wide range of CPU and loop controller boards for the 4100ES, 4100U, 4010, and 4020 families.
Shop Simplex Power Supplies → | Shop Simplex Boards →
How to Identify the Right Simplex Replacement Part
Simplex uses a consistent part-numbering scheme (e.g., 4098-9714) that makes identification straightforward. Here are the best practices:
- Locate the Part Number — Check the label on the device itself, the back of the detector, or the circuit board silk-screen printing. Simplex part numbers typically follow a XXXX-XXXX format.
- Check Your Panel Type — IDNet devices are not interchangeable with Mapnet II or conventional devices. Confirm your panel protocol before ordering.
- New vs. Refurbished — Many legacy Simplex parts (4020, 4010 era) are no longer manufactured. Our certified refurbished inventory is fully tested and offers significant cost savings.
- Use Our Search — Enter the exact part number in our search bar for instant results across our 20,000+ part inventory.
Ready to find your part? Shop All Simplex Fire Alarm Parts →
Why Buy Simplex Parts from Fire Alarm Spare Parts?
- 2,600+ Simplex parts in stock and ready to ship
- New, refurbished, and reconditioned options available
- Fast shipping with most orders dispatched within 1 business day
- 30-day return policy on all parts
- Expert support from technicians who know Simplex systems
Have a question about a specific Simplex part? Call us at 1-844-839-6844 and our team will help you find the right replacement.