Quick Answer:
The HVAC ball valve manages the flow of water, glycol, and refrigerant in HVAC systems through the quarter-turn ball system to ensure complete shut-off with low pressure. The choice of a suitable model is determined by factors such as pipe diameter, flow rate, material to be used, and whether it requires automatic control. ONERO produces a wide variety of ball valves for HVAC use, which are approved by API 6D and ISO 9001.
What Are the Common Types of HVAC Ball Valves?
Knowledge about the type of HVAC ball valves before specification will help prevent under-specification of isolation valves on the same project.
Two-way and three-way: A 2-way ball valve opens or closes a single path, and it is used for isolation and shut-off, while a 3-way ball valve has three ports used in mixing or diversion of the flow between two circuits. This is common in chilled water distribution systems where the mixing configuration controls the supply temperature.
Manually operated and electrically operated: Manually operated ball valves are suitable for low-frequency isolation points that do not need automation. The electrically actuated valves are used in fan coil units, AHUs, and zone control systems where BMS operates the valve based on demand.
Threaded connection versus flanged connection: For small-diameter pipes below DN50, threaded ends are the norm while flanged ends are ideal for larger diameter main lines. ONERO offers both types of connections for all diameters of their valves.
The HVAC ball valve sizing type differences, such as two-way, three-way, manually operated, automatic, and threaded or flanged, need to be settled before piping sizing is done.
How Is Cv Flow Coefficient Used in HVAC Sizing?
Chilled Water Flow vs Valve Cv Formula
The Cv (flow coefficient) method is the standard approach to HVAC ball valve sizing. It relates flow rate, pressure drop, and specific gravity:
Cv = Q / √(ΔP / SG)
Where Q is the flow rate in US gallons per minute, ΔP is the pressure drop across the valve in psi, and SG is the specific gravity of the fluid (1.0 for water).
Example: A chilled water circuit requires 40 GPM with a maximum allowable valve pressure drop of 4 psi.
Cv = 40 / √(4 / 1.0) = 40 / 2 = 20
Select a valve with a rated Cv of at least 20. Undersizing the Cv creates excessive pressure drop that the pump system must overcome. Oversizing reduces controllability on modulating applications.
The ball valve Cv for chilled water circuits should be sized to produce a pressure drop between 25 and 50 percent of the total circuit pressure drop at design flow. This ensures the valve has meaningful authority over the circuit.
Bore Size vs Flow Reference Table
| Nominal Size | Full Bore Cv (approx.) | Typical GPM Range | Recommended Application |
| DN15 (½”) | 14 | 3 to 8 | Fan coil units, small zone valves |
| DN20 (¾”) | 22 | 6 to 14 | FCU, room AHUs |
| DN25 (1″) | 36 | 10 to 22 | Secondary circuits, terminal units |
| DN40 (1½”) | 78 | 20 to 50 | Floor-level distribution |
| DN50 (2″) | 120 | 40 to 80 | Medium branch circuits |
| DN80 (3″) | 280 | 90 to 180 | Primary circuit isolation |
| DN100 (4″) | 480 | 160 to 320 | Chiller connections, plant mains |
Ball Valve vs Butterfly Valve in HVAC: Key Trade-Offs
Both the valves exist in HVAC systems; however, they play their roles at various stages within the distribution system.
A ball valve offers unrestricted flow through its bore along with very low pressure drop. In addition to this, the ball valve offers positive shut-off without leakage. These advantages make it more suitable for isolating equipment connections, take-offs, and terminal units.
However, butterfly valves have low costs per unit in big sizes and work well in regulating flows in header distribution pipes, where partial throttle flow is accepted. The downside is that there is more pressure loss when fully opened and the disc remains in the flow line, collecting dirt in dirty water systems.
Among the various types of HVAC ball valves, small sizes up to DN200 will remain the norm. Sizes bigger than DN200 will usually be justified to use butterfly valves in plant main piping connections.
How Should Ball Valve Material Be Selected for HVAC?
Material selection follows pipe size and media.
Brass is the standard for small-bore systems to DN50 in treated closed-circuit water and glycol. It is cost-effective, widely available, and compatible with standard HVAC water treatment chemicals.
Bronze and DI (ductile iron) suit medium-bore applications from DN50 to DN150 in open or closed circuit systems. DI is preferred for larger mains where brass cost becomes significant.
Stainless steel is specified for cleanrooms, pharmaceutical HVAC, high-purity water circuits, and corrosive environments. It carries a cost premium but eliminates corrosion risk from aggressive water chemistry.
ONERO’s range covers all four materials across the full bore size range, with material certifications and pressure-temperature ratings available per order.
Electric Actuator Integration and OEM/ODM Capability
Electric-actuated ball valves in HVAC serve fan coil unit control, AHU preheat and cooling coil isolation, and BMS-integrated zone control. The actuator must match the valve torque requirement and accept the BMS control signal, typically 0-10V or floating point for modulating applications and 24V AC/DC for simple isolation.
ONERO supplies electric-actuated ball valves as integrated assemblies, with OEM/ODM programs available for distributors and contractors who require branded products or custom wiring configurations. Actuator torque ranges and signal types are configurable to project specifications.
V-port design for precise flow control and throttling. High-performance, 2″–24″.
View ProductTypical HVAC Project Cases
Commercial building: A 20-storey office tower specified DN25 threaded 2-way ball valves with electric actuators on 240 fan coil units. ONERO supplied factory-assembled valve-actuator units with 24V AC signals, reducing site installation time.
Cleanroom: A semiconductor facility specified DN40 stainless 2-way ball valves for ISO Class 5 cleanroom AHUs. Stainless was selected to prevent corrosion from process water chemistry. ONERO supplied with material certs and pressure test records per unit.
FAQs
1. How to size a ball valve for HVAC chilled water?
Apply the Cv formula: Cv = Q / √(ΔP / SG). Use the design flow rate in GPM, set the allowable valve pressure drop at 25 to 50 percent of total circuit drop, and SG = 1.0 for water. Select a valve with a rated Cv at or above the calculated value. Sizing this way ensures the valve has adequate capacity without oversizing.
2. What Cv rating do I need for an HVAC ball valve?
The required Cv is calculated from design flow and allowable pressure drop. A DN25 full-bore ball valve has a Cv of approximately 36, suitable for 10 to 22 GPM. The ball valve Cv for chilled water circuits should be confirmed using the bore size table and sizing formula above.
