Belimo 22DC-53 : Active Duct CO2 Transmitter, Dual Output 0-5V/0-10V + 4-20 mA, NDIR Dual-Channel CO2, 2024 Hardware Rev (A-22D-A34 with 1/2" NPT), NEMA 4X / IP65, UL 2043 Plenum-Rated, 5-Year Warranty

Can I use both the voltage and current outputs at the same time?

Yes — both outputs are active simultaneously and carry the same CO2 reading. Wire the V output to one controller and the mA output to another if you need to feed two BAS systems from a single sensor. The voltage output is jumper-selectable between 0-5V and 0-10V; the current output is fixed at 4-20 mA.

What's the difference between 22DC-53 and 22DC-51?

22DC-51 has only the 0-10V voltage output. 22DC-53 adds a 4-20 mA current output alongside the voltage output. Both are 2024 hardware revision (A-22D-A34 flange, 1/2" NPT conduit adapter included) with identical CO2 sensing technology, accuracy, and range. Choose -53 when your controller needs a 4-20 mA signal, when you have long cable runs (mA is more resistant to voltage drop and EMI), or when you want to feed both V and mA controllers from one sensor.

What's the difference between 22DC-53 and 22DTC-53?

22DTC-53 measures both CO2 AND temperature (with two analog output pairs); 22DC-53 measures CO2 only (with two output types — V and mA — but only one measurement). Use 22DC-53 when you need CO2-only with dual-signal compatibility; use 22DTC-53 when you need both CO2 and temperature from the same sensor probe.

Why does the 4-20 mA output need a max 500 Ω load?

The 4-20 mA loop voltage is set internally by the sensor's transmitter circuit. With AC 24V supply, the available loop voltage caps at roughly 20V after internal drop, which limits the total loop resistance to about 500 Ω. Exceeding this load causes the loop to saturate — the output won't reach the full 20 mA at high CO2 readings. Most BAS analog inputs have 250 Ω or lower input impedance, leaving headroom for cable resistance.

Does this sensor need annual calibration?

No. The NDIR dual-channel sensing technology includes an automatic self-calibration reference channel that compensates for optical aging continuously. Unlike ABC-Logic sensors that assume periodic exposure to outdoor air to recalibrate, the dual-channel design is suited for 24/7 indoor applications (hospitals, labs, sealed buildings) where ABC-Logic would drift. Manual calibration is not required.

Is this UL 2043 plenum-rated?

Yes. The 22DC-53 is UL 2043 compliant for installation in air plenums per NEC Section 300.22(C) and IMC Section 602. The housing materials meet the low smoke-density and low heat-release requirements for return-air plenum installation.

What CO2 range does it ship with?

Factory default is 0-2000 ppm — appropriate for most occupied-space applications. If you need 0-5000 ppm (high-CO2 environments like greenhouses, brewing, fermentation, or industrial process exhaust), the range can be expanded to 0-5000 ppm using the optional Belimo A-22G-A05 Bluetooth dongle and the Belimo Duct Sensor Assistant App. The output signal then scales 0-5V/0-10V/4-20mA across the full 0-5000 ppm range.