Gentex GN-503FF (part 918-0021-002) is a 120 VAC combination photoelectric smoke and electrochemical carbon monoxide alarm with 9V battery back-up and two sets of Form A/Form C relay contacts that activate independently for smoke and CO events. It is used as an evacuation device in dwelling units such as homes, apartments, hospitals, hotels and motels. This model has been replaced by the Gentex SCRR (918-0033-002).
Smoke is annunciated with a Temporal 3 pattern and CO with a Temporal 4 pattern from a 3100 Hz horn rated 85 dBA at 10 ft. When smoke and CO are present at the same time, the smoke annunciation takes priority. The alarm is non-latching (self-restoring), and the relay contacts keep operating on battery back-up.
Specifications
| Sensors |
Photoelectric smoke; electrochemical CO cell |
| Operating voltage |
120 VAC, 60 Hz |
| Operating current |
0.070 A (relay models) |
| Auxiliary relay |
2 Form A and 2 Form C, 0.3 A |
| Battery back-up |
9V alkaline, Duracell MN1604 (included) |
| Smoke sensitivity |
2.5% nominal |
| Horn |
3100 Hz nominal, 85 dBA at 10 ft |
| Operating temperature |
40°F to 100°F |
| Size |
6.25 in. diameter (5.75 in. at base), 1.80 in. deep |
| Certifications |
ANSI/UL 217 and ANSI/UL 2034; CSFM 7263-0569:0500 |
Installation notes
- The GN-503F and GN-503FF wiring harnesses are not interchangeable; the alarm will not work with the wrong harness.
- Tandem interconnect with GN-503 Series, S1209 Series and CO1209 Series alarms only. Gentex alarms cannot be interconnected with other manufacturers' alarms.
- Up to 18 compatible alarms may be interconnected, no more than 12 of them smoke alarms; do not exceed 125 ft between alarms or 1,125 ft between the first and last alarm.
- All tandem-connected units must be powered from the same circuit (same fuse or breaker). Cap the BROWN/YELLOW tandem wire when not used.
- The relay contacts allow interfacing with a fire alarm control panel or NAC circuits.
Related models
- SCRR (918-0033-002) — the replacement model.
- GN-503 — same alarm without relay contacts.
- GN-503F — one set of Form A/Form C contacts that activate for smoke and/or CO.
- S1209 and CO1209 — Gentex smoke and CO alarms that can tandem interconnect with the GN-503FF.
Documents
FAQ
What replaces the GN-503FF?
The GN-503FF (918-0021-002) has been replaced by the Gentex SCRR (918-0033-002).
What relay contacts does the GN-503FF have?
Two sets of Form A/Form C contacts rated 0.3 A that activate independently for smoke and CO events. The relay contacts operate on battery back-up.
Can it be interconnected with other alarms?
The GN-503FF tandem interconnects only with GN-503 Series, S1209 Series and CO1209 Series alarms, up to 18 alarms with no more than 12 smoke alarms. It cannot be interconnected with other manufacturers' alarms.
How is it powered?
120 VAC, 60 Hz, with a 9V alkaline battery (Duracell MN1604) as back-up if building power is lost. The battery is included.
