Obsolete Simplex Fire Alarm Parts & Direct Replacements
Simplex panels have lifecycles measured in decades — but Simplex authorized parts support does not. When your local Johnson Controls / Simplex office tells you a TrueAlarm sensor or 4100 board is no longer available, QuickShipFire is one of the few independent suppliers in the United States that still stocks it. New-old-stock, bench-tested refurbished, and select compatible replacements.
Why Simplex Parts Are So Hard to Find — Even When Buildings Still Need Them
Simplex, founded in 1894 and now part of Johnson Controls, has installed fire alarm systems in more US commercial buildings than nearly any competitor. The catalog runs from the legacy 4001 and 4002 conventional panels through the 2120, 4100U and current 4100ES addressable platforms, plus the TrueAlarm sensor family and TrueAlert notification appliances.
Simplex obsolescence is uniquely painful for three reasons:
- The authorized channel is single-source. Unlike Notifier or Fire-Lite, Simplex parts historically have not been sold through independent distribution. Once Johnson Controls retires a SKU, the corporate channel closes — and most building owners discover this only at the next ITM cycle.
- The installed base is enormous. Hospitals, federal buildings, universities, transit hubs and major commercial high-rises were standardized on Simplex 15-30 years ago. Replacing the head-end alone is a six-figure project before labor.
- Replacement paths are not always backward-compatible. The jump from a 4100U to a 4100ES — or from a 2120 to anything current — usually means reprogramming the entire database, replacing legacy sensors, and re-mapping notification circuits.
QuickShipFire was built to keep those Simplex systems running until the building owner is genuinely ready to replace them — not when the manufacturer’s product cycle says they have to.
Obsolete Simplex Parts Currently in Stock
Below is a working snapshot of the obsolete Simplex parts we ship most often. Simplex inventory moves fast and we don’t always publish every SKU online — if your exact model is not listed, submit the part number below and we’ll check our supplier network the same day.
| Model | Description | Replaced By | Availability |
|---|---|---|---|
| 4098-9714 | TrueAlarm photoelectric smoke sensor | 4098-9714 (current rev) | In Stock |
| 4098-9733 | TrueAlarm photoelectric/heat sensor | 4098-9733 (current rev) | In Stock |
| 4098-9788 | TrueAlarm sensor base, addressable | 4098-9792 (revised) | In Stock |
| 4090-9001 | IDNet input/monitor module | 4090-9001 (rev D) | In Stock |
| 4090-9002 | IDNet control module, single relay | 4090-9116 (form-factor change) | Low Stock |
| 4906-9101 | TrueAlert horn/strobe, wall-mount | 4906-9151 (ADA candela) | Low Stock |
| 4905-9931 | TrueAlert speaker/strobe, ceiling | 4906-9931 (current) | Low Stock |
| 4100-1431 | 4100U PDI/CPU board | 4100ES upgrade required | Call to Confirm |
| 4100-9111 | 4100ES IDNet card, 250-point | 4100-9111 (current rev) | In Stock |
| 2098-9201 | Manual pull station, addressable | 2099-9201 (current) | Low Stock |
| 4001-9301 | Legacy 4001 conventional panel boards | 4007ES upgrade | Call to Confirm |
| 2120 series | Legacy 2120 modules and sensors | 4100ES retrofit | Call to Confirm |
Simplex SKUs change revisions frequently. Submit the part number below for current pricing, panel-firmware compatibility and lead time.
Simplex Cross-Reference & Replacement Guide
Simplex part numbers carry generation, application and revision data inside the SKU itself. Reading a “4098-9714” off a sensor and asking “is the current part the same?” is a fair question — and the answer depends on which revision of the TrueAlarm CPU your 4100 panel is running. Here are the cross-references we field most often:
| Legacy Simplex Part | Current Equivalent | Compatibility Notes |
|---|---|---|
| 4098-9714 (older rev) | 4098-9714 (current) | Sensor envelope identical; verify TrueAlarm CPU firmware. |
| 4098-9733 | 4098-9733 (current) | Photo-heat combo; check fixed-temp threshold. |
| 4098-9788 base | 4098-9792 base | Wiring identical; new addressing pin layout. |
| 4090-9002 module | 4090-9116 | Relay form-factor change; mounting depth same. |
| 4906-9101 horn/strobe | 4906-9151 | ADA candela ratings updated; verify field of view. |
| 4100U PDI board | 4100ES PDI | Not a drop-in. Panel-level migration required. |
| 2120 platform parts | 4100ES retrofit | End-of-line. Full head-end replacement is the path. |
| 4001 conventional panel | 4007ES | New addressable architecture; legacy NACs require interface. |
If your cross-reference isn’t in this list, submit the SKU below. We maintain an internal Simplex cross-reference database with several hundred entries and can usually return a definitive answer within one business day.
The Real Cost of a Simplex Impairment
A Simplex panel that has been flagged for a discontinued part is not just a maintenance issue — it’s a business-continuity issue. Here’s what an extended impairment actually costs a typical commercial owner:
Fire Watch Costs
When a fire alarm system is impaired, NFPA 72 (Chapter 14) and most local AHJs require a manned fire watch until the system is restored. That typically runs $25-$60 per hour, 24 hours a day. A two-week parts wait can quickly exceed $15,000.
Insurance Exposure
Commercial property policies require a functioning, code-compliant fire alarm system. A documented impairment that drags on can void coverage on a claim — or trigger a sharp premium increase at renewal.
Occupancy Risk
For hospitals, hotels, schools and multifamily, an extended impairment can force partial closures or restrict occupancy. The revenue impact dwarfs the cost of a $200 module.
Avoided Capital Expense
A full panel replacement is often $15,000 to $80,000 depending on building size. A legitimate repair-in-kind using a stocked discontinued part can keep that system running another 5-10 years.
Got Simplex Parts? We Buy New-Old-Stock
One reason we can stock so much obsolete Simplex inventory is our Got Parts program. If you’re decommissioning a Simplex 4100U or 2120 building, finishing a retrofit, or have unused TrueAlarm devices in original packaging, we want to make you an offer.
We pay fair market value for:
- New-in-box TrueAlarm sensors and bases (4098 series)
- Sealed IDNet modules (4090 series)
- Unused TrueAlert horns, strobes and speakers (4906 series)
- Spare 4100U / 4100ES boards and CPUs
- Legacy 2120 and 4001 parts in original packaging
Industries That Rely on Legacy Simplex Systems
Simplex obsolete demand is concentrated in the building types that can’t afford to wait six months for a Johnson Controls retrofit project:
- Hospitals and healthcare campuses — Joint Commission and CMS surveys require continuous fire alarm functionality. A mid-survey 4100U impairment is not optional.
- Federal and GSA-spec buildings — many were standardized on Simplex in the 1990s; the specification still pins Simplex model numbers today.
- Universities and large school districts — multi-building campuses with networked 4100ES head-ends; parity across buildings depends on stocked legacy parts.
- Class A commercial high-rises — Simplex was the default in big-city office towers for two decades; retrofitting 30+ floors is rarely budgeted in advance.
- Transit and infrastructure facilities — Simplex networked systems are common in airports, transit terminals and water/wastewater plants.
Frequently Asked Questions
How do I know if my Simplex part is obsolete?
Johnson Controls / Simplex publishes lifecycle and end-of-life notices through its authorized service network. If your local Simplex branch tells you the part is no longer available, or the model has been removed from current Simplex catalogs, it is obsolete. Submit the part number to QuickShipFire and we will confirm availability plus identify any direct replacement within one business day.
Are obsolete Simplex parts still code-legal to install?
In most cases, yes. NFPA 72 does not require replacing a working Simplex system simply because a part has been discontinued. As long as the device is listed (UL, ULC, FM) and was originally approved for the application, repair-in-kind is permitted by most AHJs. Always confirm with your local Authority Having Jurisdiction. Our NFPA 72 Compliance Guide covers the regulatory background.
Do you guarantee obsolete Simplex parts?
Yes. Every part we ship — new, new-old-stock or refurbished — carries our standard limited warranty. Refurbished Simplex components are bench-tested before they leave our warehouse. Specific terms appear on the product page for each SKU.
Can you cross-reference a discontinued Simplex model to its current production replacement?
In most cases, yes. Simplex maintains documented replacement paths — for example, the 4098-9788 base has been replaced by the 4098-9792. Submit the part number through our quote form and we’ll send the current replacement SKU plus the panel-firmware notes you need before installation.
How fast can you ship an obsolete Simplex part?
Most in-stock items ship the same day if your order is placed before noon Eastern Time. Ground transit anywhere in the continental US is typically 2 to 5 business days. Expedited and overnight shipping are available at checkout for urgent jobsite needs. Discontinued items flagged as “Call to Confirm” usually ship within 1-3 business days after stock verification.
Do you stock parts for the legacy 2120 or 4001 panels?
We carry select 2120 and 4001 modules and field devices when we can source them — these are deeply legacy SKUs and stock is intermittent. For 2120 and 4001 owners, the long-term plan is usually a 4100ES head-end retrofit; in the meantime we can often keep the system in service while you plan the project.
Do you buy old or new-old-stock Simplex parts?
Yes. If you have new-old-stock Simplex devices or unused inventory from a decommissioned project, our Got Parts program will evaluate and make an offer. This is one of the ways we maintain a steady supply of legacy TrueAlarm sensors and IDNet modules.
Request a Quote on Obsolete Simplex Parts
Send us the Simplex SKU — or describe the panel you’re working on (4100U, 4100ES, 2120, 4001, 4007ES) — and we’ll respond with availability, pricing and any TrueAlarm CPU firmware compatibility notes. Most quotes go out the same business day.
Need an Obsolete Simplex Part — Today?
Submit a part number, talk to a real specialist, get a real answer. No phone trees, no upsells, no “we’ll get back to you next week.”
Request a Quote Call +1 (833) 747-7845