What Replaces the Gentex S1209F, GN-503 and CO1209 Alarms?

CO1209The Fire Alarm Supplier
Gentex SR (917-0071-002) 120 VAC smoke alarm

Gentex replaced the S1209, GN-503 and CO1209 series with its S/C/SC/H Series in March 2024. Matched by sensor type and relay contacts, the S1209F becomes the SR, the GN-503 the SC, the GN-503F the SCR, the GN-503FF the SCRR and the CO1209 the C.

Gentex's announcement of March 19, 2024 says the new alarms replace the three legacy series and that the legacy alarms would be built through June 30, 2024, subject to component availability. Gentex now labels the S1209, GN-503 and CO1209 documents as discontinued on its resources page. The announcement refers to a cross-reference chart, but the chart is not part of the copy Gentex publishes, so the model pairs below come from comparing Gentex's legacy and current data sheets feature by feature.

Which current Gentex model replaces each discontinued one?

Discontinued model What it was Current model Current part number
S1209 (917-0059-002) 120 VAC photoelectric smoke alarm, 9V backup, no relay S 917-0070-002
S1209F (917-0057-002) Same, with one Form A and one Form C relay SR 917-0071-002
GN-503 Combination smoke and CO alarm, no relay SC 918-0031-002
GN-503F Smoke and CO, one set of Form A/Form C contacts SCR 918-0032-002
GN-503FF Smoke and CO, two sets of Form A/Form C contacts SCRR 918-0033-002
CO1209 (918-0009-002) 120 VAC carbon monoxide alarm, no relay C 918-0030-002
CO1209F (918-0010-002) CO alarm with one Form A and one Form C relay CR 918-0036-002

Three differences are worth checking before you order:

  • Relay rating. The S1209F and CO1209F data sheets rate the auxiliary relay at 0.6 A. The SR, CR and SCR are rated 0.5 A, and the two-relay SCRR 0.3 A (the same as the GN-503FF). Confirm the load on the contacts.
  • Size. The legacy alarms are 6.25 in. in diameter (5.75 in. at the base). The new series measures 5.5 in. (5.0 in. at the base), so an unpainted ring can show on the ceiling.
  • Sensing and listing. The S and SC models use multi-criteria smoke sensing that includes a photoelectric sensor and are listed to ANSI/UL 217, 9th Edition.

Does the replacement fit the existing mounting plate and wiring harness?

Plan on installing the new mounting plate and the new harness. The S/C/SC/H manual tells the installer to use the supplied mounting bracket, and both the manual and the data sheet warn that the wiring harnesses are not interchangeable and that the alarm will not work with the wrong one. Gentex's documents describe no adapter between the old connector and the new alarm.

The junction box wiring is unchanged: black to hot, white to neutral, and the brown/yellow lead to the tandem conductor. The legacy S1209 and CO1209 harnesses also carried a red/yellow lead for older Gentex alarms. The new harness does not have it.

Can new S, SC and C alarms be interconnected (tandem) with older Gentex alarms?

Yes with the three series they replace, no with anything older. The current manual says an S/C/SC/H alarm can only be tandem interconnected with other S/C/SC/H models and with the GN-503, CO1209 and S1209 series, using the brown/yellow wire. It lists the 7100/7103, 9120/9123, GN-300/GN-303, 710CS/7103CS and 7109CS/7139CS series as legacy products it will not connect to.

That matters on mixed sites. An S1209 that was tied to 9123 or 7139CS units through its red/yellow lead cannot be swapped for an S and stay interconnected with them.

Limits from the same manual:

  • A maximum of 18 compatible alarms on one tandem line, of which no more than 12 can be smoke alarms.
  • No more than 125 ft between devices and 1,125 ft between the first and last device.
  • All tandem units on the same branch circuit, controlled by the same breaker.
  • Gentex alarms are not to be connected to other manufacturers' alarms.

What do the suffixes F, FF, R and RR mean?

They describe relay contacts. The letters changed between generations:

Suffix Series Meaning in the Gentex data sheets
F S1209F, GN-503F, CO1209F One set of Form A/Form C auxiliary contacts
FF GN-503FF Two sets of Form A/Form C contacts that operate independently for smoke and CO
R SR, SCR, CR One Form A and one Form C relay
RR SCRR, STRR, SHRR Two Form A and two Form C relays
T STRR Integral 135°F thermal with rate of rise
H SHRR Isolated 135°F thermal with rate of rise

The horn pattern does not depend on the suffix: temporal 3 for smoke and heat, temporal 4 for CO. On the relay models the relay has two modes. In tandem mode, the factory default, it also changes state when another interconnected alarm signals. In local mode it follows only its own sensor. If the old S1209F relay drove a door holder, an annunciator or a panel input, set the mode the application needs. The relays operate on battery backup.

What replaces the Gentex 9120F, 9123F and 7100F?

Gentex's 2015 cross-reference replaced the AC-only 710F, 713F, 7100F, 7103F and 9120F with the 9123F. Gentex now lists the 9123 as discontinued, and we found no Gentex document that names an S Series model as its replacement. The current 120 VAC smoke alarm with relay contacts is the SR, but it will not tandem with remaining 9120 or 9123 units, so an interconnected group has to be changed together to keep working as a group. For the 7139CS and 7139LS strobe alarms, Gentex's 2022 notice announced obsolescence without naming a replacement.

If you are replacing those older series across a building, request a quote with the model numbers and quantities.

How old is too old: when must a 120 VAC smoke or CO alarm be replaced?

At ten years from the date of manufacture for smoke alarms, or sooner if the alarm fails a test or signals end of life. The Gentex manual cites NFPA 72 (2022), sections 14.4.5.6 to 14.4.5.8: smoke alarms are not to stay in service beyond 10 years from manufacture unless the manufacturer's instructions provide otherwise, CO alarms are replaced when the end-of-life signal sounds or the manufacturer's replacement date is reached, and combination alarms at whichever of the two comes first.

The S/C/SC/H Series has an internal end-of-life timer. At end of life the alarm gives three short chirps about every 45 seconds. The signal can be silenced for roughly 71 hours at a time for up to 30 days, and Gentex says to replace the alarm immediately once it starts.

The store stocks the Gentex S, SC and C lines. In-stock orders placed by 3 PM ET ship the same business day. These are 120 VAC single- and multiple-station alarms: follow the Gentex manual, NFPA 72 and your local AHJ, and where relay contacts connect to a fire alarm control panel, confirm the arrangement against that panel's documents.

Sources

Tags: Co1209, Gentex, Gn-503, Replacement guide, S1209f, Smoke alarms