Sensor Replacement Guide
The Versa MINI-345 replaces the Honeywell 5816 in the job the 5816 does most: supervising a door or window with its reed switch and magnet on a 345 MHz panel.
Same 345 MHz frequency, same serial-number enrollment, same panels — Honeywell VISTA with a 5800-series receiver, the Lyric controller, Resideo PROA7 with a PROTAKEOVER module, and 2GIG GC2, GC3, and EDGE — in a transmitter roughly one-tenth the volume of the 5816. There is exactly one 5816 job it can't take over, and it's spelled out below.
What the Honeywell 5816 is — and why it's on so many jobs
The Honeywell 5816 (originally the ADEMCO 5816, now sold under Resideo's Honeywell Home brand) is the standard two-zone door/window transmitter of the 345 MHz 5800 wireless series. Per Resideo's current spec sheet and the official ADEMCO 5816 Installation and Setup Guide (N6482V2), it transmits at 345 MHz, runs on a single CR123A 3V lithium battery, measures 3-1/16" H × 1-9/16" W × 1-3/16" D, and carries UL Residential Burglar and UL 985 Residential Fire listings. Each unit has a unique serial number that gets enrolled into the panel, is supervised as an RF-type zone, and trips a tamper when the cover comes off.
Its two independent zones are the reason it became a workhorse: Input 2 is the familiar reed switch and magnet, while Input 1 gives installers a wired closed-circuit loop (nominal 100 ms response; UL limits the wired contact to 3 feet from the transmitter) for tying a wired contact into a wireless system. Decades of VISTA installs mean there are millions of 5816s on walls — and a steady need to replace them one at a time as batteries, cases, or openings change.
Where the MINI-345 drops in
The Versa MINI-345 is a 345 MHz single-zone door/window transmitter that enrolls exactly the way a 5816 does: the panel learns its unique serial number and supervises it as an RF zone. Any panel that receives Honeywell 5800-series 345 MHz sensors receives the MINI-345 the same way:
- Honeywell VISTA panels (VISTA-15P/20P/21iP and similar) equipped with a 5800-series RF receiver such as the 5881 or a 6160RF keypad.
- Honeywell Lyric controller, which receives 5800-series 345 MHz sensors.
- Resideo PROA7 / PROA7PLUS with the PROTAKEOVER legacy-RF module installed and its rotary switch set to position 0 (5800 series). The PROTAKEOVER adds legacy 345 MHz reception alongside the panel's built-in PROSiX sensors.
- 2GIG GC2, GC3, and EDGE panels on the 345 MHz sensor bus.
For the panel-by-panel keystrokes, see our MINI-345 installation guide for VISTA 20P, Lyric, PROA7 & 2GIG EDGE and the full Versa panel compatibility guide.
One-tenth the size
The 5816 case is 3.06" × 1.56" × 1.19". The MINI-345 transmitter is 2.2" × 1" × 0.25" — about 1/10th the volume, thin enough to disappear on a window frame instead of announcing itself.
Bluefield install confirmation
A blue LED lights when the magnet is within range, green flashes on each transmission, and red flashes on low battery — you confirm placement at the sensor before committing the tape, no trips back to the panel.
Tool-free service
The cover slides off for battery changes and color swaps — no prying. It runs on a Panasonic CR2032 coin cell, rated for 5+ years, and the tamper trips on cover removal just like the 5816.
The one case where it doesn't: the wired loop
If the 5816 you're replacing has wires landed on its loop terminals — a recessed contact, a roller-ball in a door jamb, an overhead-door contact wired back to the transmitter — the MINI-345 has no equivalent input. Your options: leave the 5816 in place on that opening (they coexist fine; both are supervised 345 MHz RF zones), or re-do the opening with the MINI-345's own reed and magnet if the geometry allows surface mounting. Per the 5816's official guide, its wired loop is closed-circuit only with a nominal 100 ms response, and UL installations limit the wired contact to 3 feet from the transmitter — so these zones are a small, identifiable minority on most accounts.
Same 345 MHz radio — smaller, easier to service, easier on the homeowner
Nobody replaces a 5816 because of its radio. The 5800-series RF is why it survived two decades on VISTA accounts — and switching to the MINI-345 doesn't trade that away. It transmits on the same 345 MHz band and, in Versa's range testing, delivers roughly 90% of the 5816's RF range from a case one-tenth its size — nine-tenths of the reach in one-tenth of the package. It enrolls and supervises exactly like any 5800-series RF zone (unique serial number, tamper reporting, supervised low battery), and its manual requires the panel's Go/No Go signal test before permanent mounting — the same discipline Honeywell's own guide calls for. In a residential install, the receiver and the building decide your range budget long before that last 10% does; if a 5816 held signal at an opening, the MINI-345 almost always will, and the Go/No Go test settles it in seconds. What you change is everything wrapped around the radio:
Battery service in seconds
The 5816's case opens by releasing its locking tab; the MINI-345's cover slides off vertically — no tab, no tools, no pulling the sensor off the frame. Drop in a fresh CR2032 with the + side up, slide the cover back, done.
Color the homeowner picks
Honeywell offers brown as a separate model — the 5816BR, sold in 3-packs. The MINI-345 stays one SKU: snap on a black or brown cover from a 10-pack to match dark frames or wood trim, with no re-enrollment and no second sensor on the truck.
A footprint that disappears
At 2.2" × 1" × 0.25", the MINI-345 sits flush where the 1.19"-deep 5816 stands off the trim. On a visible window frame, that quarter-inch profile is the difference between a sensor the homeowner tolerates and one they never notice.
Cover swaps take seconds and no tools — here's how to change Versa sensor covers. Stock the MINI Black Covers (10-pack) and MINI Brown Covers (10-pack) and one sensor matches every trim color on the job.
Spec comparison: 5816 vs. MINI-345
Every figure below comes from the manufacturers' own installation documents — the ADEMCO 5816 guide (N6482V2) and Resideo's published 5816 specifications, and the Versa MINI-345 Installation & Setup Guide.
| Spec | Honeywell 5816 | Versa MINI-345 |
|---|---|---|
| Frequency | 345 MHz (5800 series) | 345 MHz (5800-series compatible) |
| Zones | 2 — wired closed-circuit loop (Input 1) + reed switch (Input 2) | 1 — reed switch + magnet |
| Enrollment | Unique serial number, supervised RF type | Unique serial number, supervised RF type |
| Transmitter size | 3-1/16" H × 1-9/16" W × 1-3/16" D | 2.2" × 1" × 0.25" — ~1/10th the volume |
| Magnet gap, wood | 1.36" typical | 1" maximum |
| Magnet gap, steel/metal | 0.78" typical | 1/4" maximum |
| Battery | CR123A 3V lithium | Panasonic CR2032 3V lithium, rated 5+ years |
| Install confirmation | — | Bluefield LEDs: blue = magnet in range, green = transmit, red = low battery |
| Cover / service | Snap-on cover, locking-tab release | Slide-off cover, tool-free |
| Color options | White; brown is a separate model (5816BR, 3-pack) | One sensor — snap-on black or brown covers (10-packs), no re-enrollment |
| Tamper | Cover-removal tamper | Cover-removal tamper |
| Humidity | 95% RH non-condensing | 95% RH non-condensing |
| Listings | UL Residential Burglar, UL 985, ULC, CSFM | UL listed, FCC, IC |
Swapping a 5816 for a MINI-345: the 15-minute version
Delete or repurpose the zone
In panel programming, delete the 5816's serial number from the zone (or plan to overwrite it). On a two-zone 5816 install, remember Inputs 1 and 2 are separate zones — confirm which one you're replacing.
Enroll the MINI-345
Learn the MINI-345's serial number into the zone as a supervised RF transmitter, exactly as the 5816 enrolled. Zone type and response stay as programmed. Panel-specific keystrokes are in the install guide.
Run a Go/No Go test
Before mounting permanently, verify signal strength from the mounting location using the panel's Go/No Go test mode — the MINI-345 manual calls for this on every install, same as Honeywell's guidance.
Mount with Bluefield confirmation
Sensor on the frame, magnet on the moving side. Close the door or window and watch for the solid blue LED — magnet in range. Keep gaps under 1" on wood and 1/4" on metal, and keep the pair off metallic surfaces where possible.
Verify at the panel
Trip the opening, watch the green transmit flash, and confirm the zone faults and restores at the keypad. Done — the old 5816's footprint wipes clean, and the opening is now serviced without tools.
The MINI-345 ships from US stock, alongside 319.5 MHz and 433 MHz versions of the same sensor for Qolsys and DSC panels.
Replacing 5800MINIs instead of 5816s? That's an even more direct swap — the MINI-345 shares the 5800MINI's exact footprint. Read the 5800MINI replacement guide, or browse all Versa door & window sensors.
Frequently asked questions
What is a direct alternative to the Honeywell 5816?
The Versa MINI-345 is a 345 MHz door/window transmitter that replaces the Honeywell 5816 on reed-and-magnet zones, delivering roughly 90% of the 5816's RF range from one-tenth of its volume. It enrolls by serial number as a supervised RF zone on the same panels — VISTA with a 5800-series receiver, Lyric, Resideo PROA7 with PROTAKEOVER, and 2GIG GC2/GC3/EDGE — in a case about one-tenth the 5816's volume.
Does the Versa MINI-345 have a wired auxiliary loop like the 5816?
No. The Honeywell 5816 is a two-zone transmitter with a wired closed-circuit loop (Input 1) plus a reed switch (Input 2); the MINI-345 is a single-zone reed-and-magnet transmitter. If a 5816 is supervising a wired contact through its loop terminals, keep the 5816 on that opening — the MINI-345 replaces the far more common reed-zone installs.
What panels does the MINI-345 work with?
Any panel that receives Honeywell 5800-series 345 MHz sensors: Honeywell VISTA panels with a 5800-series RF receiver (5881 or 6160RF), the Honeywell Lyric controller, Resideo PROA7/PROA7PLUS with the PROTAKEOVER module set to position 0, and 2GIG GC2, GC3, and EDGE panels.
What battery does the MINI-345 use, and how does it compare to the 5816's?
The MINI-345 runs on one Panasonic CR2032 3V lithium coin cell rated for 5+ years. The Honeywell 5816 uses one CR123A 3V lithium. Both batteries are supervised by the panel, and both sensors flag low battery — the MINI-345 adds a red LED flash at the sensor itself.
How much smaller is the MINI-345 than the Honeywell 5816?
The 5816 case measures 3-1/16" × 1-9/16" × 1-3/16"; the MINI-345 transmitter measures 2.2" × 1" × 0.25". That's roughly one-tenth the volume — a quarter-inch-thin profile that sits flush on window frames where the 5816 is conspicuous.
Can the MINI-345 match dark or wood-tone trim like the 5816BR?
Yes — without buying a different sensor. Honeywell sells brown as a separate model (the 5816BR, in 3-packs); the MINI-345 uses snap-on covers instead, sold in black and brown 10-packs, so one sensor matches white, dark, or wood-tone trim with no re-enrollment and no extra SKU on the truck.
Sources: Resideo 5816 product specifications; ADEMCO 5816 Installation and Setup Guide (N6482V2 Rev. D); Versa MINI-345 Installation & Setup Guide.
