Belimo 22G15-5A5 : CO2 Gas Monitor, 0-5,000 ppm, 3-Level Alarm, 1 Relay + 2 Analog + BACnet, CAN Bus, LCD, NEMA 2, UL 2075, 24V, 5-Yr Warranty

What does the 22G15-5A5 measure and what's it used for?

It's a factory-calibrated Carbon Dioxide monitor for life-safety gas detection in HVAC and building applications. Measuring range is 0-5,000 ppm; sensor technology is Non-Dispersive Infrared (NDIR) dual-channel (reference compensation). Typical applications: extended-range CO2 monitoring in spaces with elevated baseline — gymnasiums, auditoriums, dense classroom occupancy, food processing, breweries, fermentation rooms. Dual-channel NDIR is more accurate at higher concentrations than ABC logic. Required by code in many jurisdictions: ASHRAE 62.1 (demand-controlled ventilation), Title 24, IECC.

What's different about the A variant?

Belimo 22G monitors come in three feature tiers: A = 1 relay + 2 configurable analog outputs + CAN bus + BACnet MS/TP (most flexible); B = 2 relays + CAN bus + BACnet MS/TP (dual-relay sequencing); C = CAN bus only (lowest cost, pairs with C-22G accessory modules for relay/analog/BACnet aggregation). This SKU is the A variant: full-feature variant with one SPDT relay output for direct fan/damper activation, plus two configurable analog outputs (0-5V, 0-10V, 1-5V, 2-10V, 4-20 mA — all switch-selectable) for BAS integration. Both CAN bus and BACnet MS/TP communication, allowing standalone networking with up to 32 monitors AND native BMS integration.

How does the three-level alarm work?

Three escalating thresholds, all field-configurable via the on-housing LCD interface or via BACnet/CAN bus: Level 1 (warning) — red LED illuminates as an early-stage notification; Level 2 (elevated) — red LED at higher intensity / pattern indicates progression; Level 3 (emergency) — white strobe LED plus 80 dB audible horn @ 1 m (3.3 ft) demanding immediate evacuation or maximum ventilation. The horn is sufficient to be heard over typical mechanical room and parking garage ambient noise. Wire the relay outputs (on A/B variants) to fans, dampers, or BAS alarm inputs to trigger the corresponding response.

Where should I install this monitor?

Wall-mount, height per gas density and local code: CO and CO2 are roughly the same density as air, so install at 4-6 ft above the floor (occupant breathing zone). NO2 is heavier than air, so install at 1-3 ft above the floor. Refrigerants are much heavier than air, so install 1-2 ft above the floor. Coverage is approximately 50 ft (15 m) radius / 7,500 ft² (700 m²) per unit assuming unobstructed airflow — walls, full-height shelving, elevator shafts, and large equipment chests reduce effective coverage. For larger or partitioned spaces, deploy multiple monitors on the CAN bus daisy chain. Always verify mounting location with the local AHJ (Authority Having Jurisdiction) and applicable code.

How is the sensor calibrated?

Belimo gas monitors ship factory calibrated — no calibration required at installation. However, sensor modules require annual recalibration per UL 2075 and Belimo specifications. Recalibration is performed on-site using a Belimo calibration kit (zero and span verification with traceable calibration gas). When a sensor reaches end-of-life or fails calibration verification, the sensor module (R-G15-005 for this gas type) is field-replaceable — the module swaps out at the unit without replacing the entire monitor. Plan calibration as part of annual life-safety system inspection alongside fire alarm and sprinkler tests.

How is this CO2 range different from the other 22G15 variants?

Three ranges in the 22G15 family: 0-2,000 ppm (suffix 3, NDIR ABC) for IAQ and demand-controlled ventilation; 0-5,000 ppm (suffix 5, dual-channel NDIR) for elevated-baseline spaces; 0-10,000 ppm (suffix 6, dual-channel NDIR) for life-safety leak detection. Each range uses a different replacement sensor module (R-G15-003 / -005 / -006).

How does the CAN bus daisy chain work?

Up to 32 22G monitors share a single CAN bus segment. Run a single 22-24 AWG twisted-pair shielded cable from monitor to monitor in a daisy-chain topology — no star topology, no T-branches. Each monitor's individual sensor data is transmitted on the CAN bus and can be read by other monitors or by a communication module / relay unit. The daisy-chain architecture dramatically reduces wiring in large installations vs running individual analog or BACnet drops for each monitor. Termination resistors at the bus endpoints are required.

Does it need 24V power?

Yes — 24 VAC or 24 VDC supported (AC 21.6-26.4V / DC 13.5-26.4V). Power consumption is 5 VA AC / 1.7 W DC. Note: per CSA/UL 61010-1 listing, all gas monitors and communication modules are rated to AC 24V only — for vehicle-emissions monitors (CO, NO2, CO+NO2), AC/DC 24V is acceptable under ULC-S588 and UL 2075. Verify with your AHJ which power supply rating applies to your installation. Compatible with standard 24V control transformers; reserve dedicated transformer capacity for the gas monitor system rather than sharing with actuators (the 80 dB horn draws significant power during alarm events).