The Belimo Z3050QS-E is a ZoneTight (QCV) 3-way diverting zone valve body with 1/2" sweat connections, a Cv of 1 and a linear flow characteristic. It is used in closed chilled and hot water systems for switching functions and 2-point controls, and it takes a CQB(X) non fail-safe or CQKB(X) electronic fail-safe ZoneTight actuator, sold separately.
The change-over valve fits in space-restricted areas, assembles without tools, and has a 0% leakage rate. Common applications include unit ventilators, fan coil units, VAV reheat coils, fin tube casing, radiant panels and duct coils.
Specifications: Belimo technical data sheet Z3050QS-E, dated 2025-01-09. Last reviewed 2026-10-09.
Best For
- Closed chilled and hot water systems, up to 60% glycol
- Switching functions and 2-point controls on the water side of air-handling units and heating systems
- Change-over duty where a 1/2" sweat valve with a Cv of 1 fits the design
- Stocking a valve body for field assembly with a CQB(X) or CQKB(X) ZoneTight actuator
Warranty
Belimo backs ZoneTight zone valves with a 5-year warranty.
If the temperature exceeds the 212°F operating range because of a boiler control failure, the valve safely contains the hot water, but the manufacturer's product warranty becomes invalid.
Key Features
Zero leakage
A 0% leakage rate, 40 psi close-off pressure and a 360 psi body pressure rating.
3-way diverting, linear
Linear flow characteristic with flow possible in both directions through the valve.
Tool-free snap assembly
The actuator plugs onto the valve by hand, with the mounting orientation selectable in 180° increments.
Two actuator families
Accepts CQB(X) non fail-safe and CQKB(X) electronic fail-safe ZoneTight actuators.
Forged brass body
Chrome plated brass ball, brass stem, EPDM O-ring stem seal and a PTFE seat with EPDM O-ring.
Fluid range
Chilled or hot water up to 60% glycol, 36...212°F [2...100°C].
ZOT Supply is an authorized distributor of Belimo products.
Technical Specifications
| Valve: Belimo Z3050QS-E | |
|---|---|
| Valve size | 0.5" [15], DN 15 |
| Flow pattern | 3-way Diverting |
| Pipe connection | Sweat |
| Cv | 1 |
| 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% |
| Flow direction | both directions possible |
| Installation orientation | upright to horizontal (in relation to the spindle); not in a hanging position with the stem pointing downwards |
| Flow setting | remove the end stop clip at the actuator to get the 90° angle of rotation needed for change-over functionality |
| 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 | 0.4 lb [0.18 kg] |
| California Prop 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 |
| Assembly dimensions with CQ actuator | |
|---|---|
| Dimension A | 4.5" [114] |
| Dimension B | 2.0" [52] |
| Dimension C | 3.7" [93] |
| Dimension D | 2.6" [65] |
| Dimension E | 1.0" [25] |
| Dimension F | 1.0" [26] |
| Assembly dimensions with CQK actuator | |
|---|---|
| Dimension A | 4.5" [114] |
| Dimension B | 2.0" [52] |
| Dimension C | 3.8" [97] |
| Dimension D | 2.7" [69] |
| Dimension E | 1.0" [25] |
| Dimension F | 1.0" [26] |
Documentation
FAQ
What is the Cv of the Belimo Z3050QS-E?
The Z3050QS-E valve has a Cv of 1, a 1/2" [DN 15] sweat connection and a linear flow characteristic.
Is the Z3050QS-E a mixing or diverting valve?
It is a 3-way diverting (change-over) zone valve. Flow is possible in both directions.
Does the actuator end stop clip need to be removed?
Yes. The end stop clip at the actuator has to be removed to get the 90° angle of rotation needed for change-over functionality.
What are the pressure and temperature limits?
Body pressure rating 360 psi, close-off pressure 40 psi, maximum differential pressure 40 psi, and fluid temperature 36...212°F [2...100°C] for chilled or hot water up to 60% glycol.
How must the valve be oriented?
Install it upright to horizontal. Do not install it hanging with the stem pointing downwards.
Which actuators fit the Z3050QS-E?
CQB(X) non fail-safe and CQKB(X) electronic fail-safe ZoneTight actuators. The actuator snaps on without tools.
- Valve Pattern:
- 3-Way
- Valve Size:
- 1/2 Inch
- Connection Type:
- Sweat
- CV Rating:
- 1.0
- Max Close-Off Pressure:
- 40 psi
- Max Operating Pressure:
- 360 psi
- Medium Temperature Range:
- 36-212 °F
- Body Material:
- Forged Brass
- Actuator Type:
- Valve Only
