Siemens HI921 — intelligent addressable thermal (heat) detector for Cerberus PRO and FireFinder systems, S54320-F5-A2.
A shock-resistant thermistor is read by microprocessor signal processing, removing the thermal lag of a mechanical sensing element. It plugs into a two-wire signal line circuit, occupies one address, and carries ISOtechnology isolation so a loop can run as True Class-X.
- Seven field-selectable settings: fixed 135, 145, 155, 165 or 175°F, plus rate-of-rise 15°F/min at 135°F or 175°F
- Configurable 40°F low-temperature warning for freeze risk
- 16 to 30 VDC; 250 µA standby, 410 µA alarm maximum
- 50 ft. (15.24 m) maximum spacing on centers, 2,500 sq. ft.
- Tri-color LED, 360° view: green normal, yellow replace, red alarm
- UL 521 and ULC Listed; CSFM 7272-0067:0258
It mounts on a DB-11, DB-11E or DB-11C base, on the DB2-HR relay base, or on an ABHW-4S audible base. Siemens states it may be installed on the same initiating circuit as the older FirePrint HFP-11 and HFPT-11; that is loop sharing, not replacement. OH921 is the multi-criteria head in this family and HI921 the heat-only one.
