The Belimo Z3075QS-J+CQKB24-S-LL is a 3/4" sweat, 3-way diverting ZoneTight zone valve assembly: the Z3075QS-J forged brass ball valve (Cv 4.6, 0% leakage, 40 psi close-off) with the CQKB24-S-LL electrical fail-safe on/off actuator for AC/DC 24 V supply. On power loss it drives to fail position 100% Open. A built-in SPST auxiliary switch is rated 1 A resistive @ DC 30 V.
Suited to large commercial buildings where higher close-off and the ability to change flow are needed. The valve fits space-restricted areas and assembles without tools: the actuator snaps onto the valve by hand, and its mounting orientation can be turned in 180° increments.
Specifications per Belimo Z3075QS-J technical data sheet rev 2025-01-09; CQKB24-S-LL actuator data sheet rev 2024-03-15. Reviewed 2026-10-09.
Best For
- Switching functions and 2-point control on the water side of air-handling units and heating systems
- Change-over (3-way diverting) duty in closed chilled and hot water systems
- Unit ventilators, fan coil units, VAV reheat coils, fin tube casing, radiant panels and duct coils
- Two-position (on/off) zone control
- Zones that need the valve driven to fail position 100% Open on power loss
- End position indication, interlock control or fan startup from the auxiliary switch
Warranty
Belimo ZoneTight valves carry a 5-year warranty. If fluid temperature exceeds the 212°F operating range because of a boiler control failure, the valve will safely contain the hot water, but the manufacturer warranty becomes invalid and valve and actuator replacement is at the expense of others.
Key Features
3-way diverting ball valve
Diverting flow pattern for change-over duty, linear flow characteristic, Cv 4.6 and 0% leakage.
40 psi close-off
Close-off pressure 40 psi, maximum differential pressure 40 psi, body pressure rating 360 psi.
Electrical fail-safe
Drives to fail position 100% Open on power loss. Bridging time 2 s, fail-safe running time <60 s.
Auxiliary switch
1x SPST, 1 A resistive @ DC 30 V, for end position indication, interlock control or fan startup.
Tool-free snap assembly
Actuator plugs onto the valve by hand; no tools or linkage needed.
Sweat connection
3/4" sweat ends; flow in both directions; install upright to horizontal.
ZOT Supply is an authorized distributor of Belimo products.
Technical Specifications
Valve: Belimo Z3075QS-J
| Valve size | 0.75" [20] (DN 20) |
| Flow pattern | 3-way Diverting |
| Pipe connection | Sweat |
| Cv | 4.6 |
| Fluid | chilled or hot water, up to 60% glycol |
| Fluid temp range (water) | 36...212°F [2...100°C] |
| Body pressure rating | 360 psi |
| Close-off pressure Δps | 40 psi |
| Differential pressure Δpmax | 40 psi |
| Flow characteristic | linear |
| Leakage rate | 0% |
| Operating mode | change-over zone valve adjusted by a rotary actuator controlled by an on/off signal |
| Flow direction | both directions possible |
| Flow setting | remove the end stop clip at the actuator to get the 90° angle of rotation needed for the change-over functionality |
| Installation orientation | upright to horizontal (in relation to the spindle); not in a hanging position with the stem pointing downwards |
| Actuator mounting | tool-free snap assembly; mounting orientation selectable in 180° increments |
| Water quality | keep free from particle debris; installation of a suitable strainer is recommended |
| Servicing | maintenance-free |
| Valve body | forged brass |
| Stem | brass |
| Stem seal | EPDM O-ring |
| Seat | PTFE, O-Ring EPDM |
| O-ring | EPDM (lubricated) |
| Ball | chrome plated brass |
| Suitable actuators | Non Fail-Safe CQB(X); Electronic fail-safe CQKB(X) |
| Valve weight | 0.53 lb [0.24 kg] |
| California Proposition 65 | WARNING: This product can expose you to lead which is known to the State of California to cause cancer and reproductive harm. For more information go to www.p65warnings.ca.gov |
Actuator: Belimo CQKB24-S-LL
| Actuator | CQKB24-S-LL: On/Off, Electrical fail-safe, 24 V |
| Fail position | 100% Open |
| Nominal voltage | AC/DC 24 V |
| Nominal voltage frequency | 50/60 Hz |
| Nominal voltage range | AC 19.2...28.8 V / DC 21.6...28.8 V |
| Power consumption in operation | 2.5 W |
| Power consumption in rest position | 0.5 W |
| Transformer sizing | 5 VA |
| Auxiliary switch | 1x SPST, 1 A resistive @ DC 30 V |
| Switching capacity auxiliary switch | 1 A resistive @ DC 30 V |
| 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 |
| Bridging time (PF) | 2 s |
| Pre-charging time | 5...20 s |
| Angle of rotation | 90° |
| Angle of rotation note | adjustable with mechanical stop |
| Running time (motor) | 75 s / 90° |
| Running time fail-safe | <60 s |
| Noise level, motor | 35 dB(A) |
| Noise level, fail-safe | 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 |
| UL 2043 compliant | Suitable for use in air plenums per Section 300.22(C) of the NEC and Section 602 of the IMC |
| Ambient humidity | Max. 95% RH, non-condensing |
| Ambient temperature | 35...104°F [2...40°C] |
| Storage temperature | -40...176°F [-40...80°C] |
| Actuator weight | 0.57 lb [0.26 kg] |
| Housing material | UL94-5VA |
| Auxiliary switch wiring | S1 / S2, NO |
Assembly dimensions
| Dimensions with CQK actuator, A / B / C | 4.5" [114] / 2.4" [60] / 4.0" [101] |
| Dimensions with CQK actuator, D / E / F | 2.8" [70] / 1.2" [30] / 1.2" [31] |
Documentation
FAQ
What is the Cv of the Belimo Z3075QS-J+CQKB24-S-LL?
Cv 4.6, with a linear flow characteristic and 0% leakage.
What close-off pressure does the Z3075QS-J+CQKB24-S-LL handle?
40 psi close-off, 40 psi maximum differential pressure and a 360 psi body pressure rating.
Does the end stop clip need to be removed on the Z3075QS-J+CQKB24-S-LL?
Yes. Remove the end stop clip at the actuator to get the 90° angle of rotation needed for the change-over functionality.
What position does the Z3075QS-J+CQKB24-S-LL fail to on power loss?
Fail position 100% Open. The fail-safe running time is under 60 s.
What is the auxiliary switch rating on the Z3075QS-J+CQKB24-S-LL?
1x SPST, 1 A resistive @ DC 30 V. Apply only AC line voltage or only UL Class 2 voltage to the switch terminals, not both.
What transformer size does the Z3075QS-J+CQKB24-S-LL need?
Transformer sizing 5 VA at AC/DC 24 V; 2.5 W in operation and 0.5 W in rest position.
- Valve Pattern:
- 3-Way
- Valve Size:
- 3/4 Inch
- Connection Type:
- Sweat
- CV Rating:
- 4.6
- Actuator Type:
- Fail-Safe
- Voltage:
- 24VAC/DC
- Control Signal:
- On/Off
- Auxillary Switch:
- (1) SPST 1A @ 30VDC
