The Belimo Z2050Q-J+CQB24-SR-L is an assembly combining the Z2050Q-J 2-way 1/2 in. NPT ZoneTight zone valve (Cv 5.9, 0% leakage, 75 psi close-off) with the CQB24-SR-L 24 VAC/DC non-spring return actuator under modulating 2-10 vdc control. At 2 VDC the valve is open and at 10 VDC it is closed.
The CQB24-SR-L snaps onto the valve by hand in 180° increments with no tools or linkage. It draws 0.3 W in operation, sizes to a 1 VA transformer and carries a plenum or appliance cable termination.
Specifications on this page are taken from belimo_Z2050Q-J_CQB24-SR-L_assembly_en-us.pdf (valve data rev. 2024-12-17; actuator data rev. 2024-06-27). Figures are as published by Belimo and are subject to change.
Best For
Belimo lists the QCV zone valves for large commercial buildings where higher close-off and field-adjustable flow are wanted. Documented applications are unit ventilators, fan coil units, VAV reheat coils, fin tube casing, radiant panels and duct coils. Modulating 2-10 VDC control makes it a fit where a controller trims coil output rather than cycling it.
Warranty
Belimo warrants all components for 5 years from the date of production. Note that exceeding the 212°F fluid temperature limit voids the manufacturer warranty even though the valve will safely contain the water.
Key Features
Field-Adjustable Cv
Maximum flow is set by moving the end stop clip in 2.5° increments, giving a Cv from 0.5 to the nominal 5.9 without changing the valve body.
Zero Leakage Shutoff
Leakage rate is 0% with 75 psi close-off, so the coil is fully isolated during unoccupied periods and no energy is lost through a seeping valve.
Tool-Free Snap Assembly
The actuator plugs onto the valve flange by hand, and mounting orientation can be turned in 180° increments. No linkage or tools are required.
Forged Brass Ball Construction
Forged brass body, chrome-plated brass ball, PTFE seat and double EPDM O-rings. Ball valve construction resists the clogging that affects globe-style seats.
2-10 VDC With Position Feedback
The actuator accepts 2-10 VDC (or 4-20 mA with a ZG-R01 resistor) and returns a 2-10 VDC position feedback signal to the controller.
Plenum Rated
The actuator is UL 2043 compliant and suitable for use in air plenums per NEC 300.22(C) and IMC Section 602.
Technical Specifications
Valve Body
| Valve pattern | 2-way |
| Valve size | 0.5" [15 mm], DN 15 |
| Cv | 5.9 |
| Pipe connection | Internal thread, NPT (female) |
| Fluid | Chilled or hot water, up to 60% glycol |
| Fluid temperature range | 36...212°F [2...100°C] |
| Body pressure rating | 360 psi |
| Close-off pressure | 75 psi |
| Differential pressure max | 40 psi |
| Flow characteristic | Equal percentage |
| Leakage rate | 0% |
| Controllable flow range | 75° |
| Angle of rotation | Operating range 15...90° |
| Installation orientation | Upright to horizontal (in relation to the spindle) |
| Servicing | Maintenance-free |
| Valve body material | Forged brass |
| Ball | Chrome plated brass |
| Stem | Brass |
| Stem seal | EPDM O-ring |
| Seat | PTFE with EPDM O-ring |
| O-ring | EPDM (lubricated) |
| Valve body weight | 0.37 lb [0.17 kg] |
Valve body weight is the current TDS rev 2024-12-17 figure. The superseded assembly PDFs rev 2024-06-12 list 0.35 lb [0.16 kg].
Actuator - CQB24-SR-L
| Nominal voltage | 24 VAC/DC |
| Nominal voltage range | AC 19.2...28.8 V / DC 21.6...28.8 V |
| Nominal voltage frequency | 50/60 Hz |
| Control signal | Modulating 2-10 VDC |
| Valve position at 2 VDC | Open |
| Valve position at 10 VDC | Close |
| Operating range Y | 2...10 V |
| Operating range Y note | 4-20 mA with ZG-R01 (500 ohm, 1/4 W resistor) |
| Position feedback U | 2...10 V |
| Power consumption in operation | 0.3 W |
| Power consumption in rest position | 0.3 W |
| Transformer sizing | 1 VA |
| Electrical connection | 22 GA plenum cable, 3 ft [1 m], with 1/2" NPT conduit connector |
| Overload protection | Electronic throughout 0...90° rotation |
| Electrical protection | Actuators are double insulated |
| Angle of rotation | 90°, adjustable with mechanical stop |
| Running time (motor) | 75 s / 90° |
| Noise level, motor | 35 dB(A) |
| Position indication | Pointer |
| Power source | UL Class 2 Supply |
| Degree of protection IEC/EN | IP40 |
| Degree of protection NEMA/UL | NEMA 2 |
| Enclosure | UL Enclosure Type 2 |
| Agency listing | cULus acc. to UL60730-1A/-2-14, CAN/CSA E60730-1:02; CE acc. to 2014/30/EU and 2014/35/EU |
| Quality standard | ISO 9001 |
| Plenum rating | UL 2043 compliant - suitable for use in air plenums per NEC 300.22(C) and IMC Section 602 |
| Ambient humidity | Max. 95% RH, non-condensing |
| Ambient temperature | 35...104°F [2...40°C] |
| Storage temperature | -40...176°F [-40...80°C] |
| Housing material | UL94-5VA |
| Actuator weight | 0.55 lb [0.25 kg] |
Assembly Dimensions (CQ)
| A | 4.5" [114 mm] |
| B | 2.0" [52 mm] |
| C | 3.1" [80 mm] |
| D | 2.6" [65 mm] |
| E | 1.0" [25 mm] |
| F | 1.0" [26 mm] |
End Stop Clip Positions
Maximum flow is set by moving the end stop clip. Values below are Belimo published V'max figures for the Z2050Q-J. Runtimes shown are for 75 s actuators.
| Clip position | Cv (V'max) | Runtime |
|---|---|---|
| 1 | 0.5 | 30 s |
| 2 | 0.7 | 37 s |
| 3- | Not available | 41 s |
| 3 | 1.2 | 43 s |
| 4 | 1.7 | 49 s |
| 4+ | Not available | 51 s |
| 5 | 2.4 | 55 s |
| 5+ | Not available | 58 s |
| 6 | 3.4 | 62 s |
| N | 4.8 | 68 s |
| No end stop | 5.9 | 75 s |
Source: Belimo Quick Mount Visual Instruction Manual 71775-00001.L / 71694-00001.K.
Documentation
Z2050Q-J + CQB24-SR-L Assembly Technical Data Sheet- Z2050Q-J Valve Technical Data Sheet
- CQ Actuator Quick Mount Instruction Manual
- Belimo ZoneTight Zone Valve Brochure
- Belimo Zone Valve Guide Specifications
Frequently Asked Questions
What is the Cv of the Belimo Z2050Q-J?
The nominal Cv is 5.9 with no end stop clip fitted. Belimo publishes reduced Cv values of 4.8, 3.4, 2.4, 1.7, 1.2, 0.7 and 0.5 for the selectable clip positions, so maximum flow can be set in the field without changing the valve.
Will the Z2050Q-J shut off completely?
Yes. Belimo rates the valve at 0% leakage with a close-off pressure of 75 psi and a body pressure rating of 360 psi.
What fluids and temperatures does it handle?
Chilled or hot water with up to 60% glycol, over a fluid temperature range of 36 to 212°F (2 to 100°C). Exceeding 212°F voids the manufacturer warranty.
How does the CQB24-SR-L respond to the control signal and to power loss?
At 2 VDC the valve is open and at 10 VDC it is closed. Source: the wiring diagram on the CQB24-SR-L assembly data sheet.
What size transformer does the CQB24-SR-L need?
Belimo specifies 1 VA for this actuator, with 0.3 W draw in operation and 0.3 W at rest.
Can the actuator be installed in an air plenum?
Yes. The actuator is UL 2043 compliant and Belimo lists it as suitable for use in air plenums per NEC Section 300.22(C) and IMC Section 602.
Can the valve be mounted in any orientation?
It can be installed upright through horizontal. Belimo prohibits hanging installation with the stem pointing downwards.
Other Z2050Q-J Configurations
Z2050Q-J · Z2050Q-J.1 · Z2050Q-J+CQB24-3 · Z2050Q-J+CQB24-SR-R · Z2050Q-J+CQBUP-3 · Z2050Q-J+CQKB24-LL · Z2050Q-J+CQKB24-RR · Z2050Q-J+CQKB24-S-LL
Belimo warrants all components of the ZoneTight valve and actuator assembly for 5 years from the date of production. Warranty terms are stated in the Belimo Zone Valve Guide Specifications (rev. July 22, 2025). Operating the valve above its 212°F fluid temperature rating voids the manufacturer warranty.
- Valve Pattern:
- 2-Way
- Valve Size:
- 1/2 Inch
- Connection Type:
- NPT
- CV Rating:
- 5.9
- Actuator Type:
- Non Fail-Safe
- Voltage:
- 24VAC/DC
- Control Signal:
- 2-10VDC
- Auxillary Switch:
- None
