Valves and flow equipment for HVAC systems

HVAC systems are used for heating, cooling, ventilation and indoor condition control in buildings, technical facilities, hotels, hospitals, industrial areas and marine applications. Their operation is based on hot water, chilled water, glycol, steam, condensate, condenser water and auxiliary service circuits.

Valves in HVAC systems are selected according to flow rate, temperature, pressure, differential pressure, fluid type, circuit function and control system requirements. Correct selection helps limit insufficient flow through heat exchangers, fan coils, air handling units and radiators, as well as hydraulic instability in variable-load circuits.

Typical applications

• Hot water circuits for space heating, radiators and fan coils.
• Chilled water and glycol circuits for chillers, air handling units and heat exchangers.
• Condenser water networks on chillers, condensers and cooling towers.
• Steam and condensate networks for air heaters, heat exchangers and substations.
• Heating and cooling substations with heat exchangers and secondary circuits.
• Filling, draining, venting, bypass and recirculation lines.
• Circulation pumping stations, hydraulic balancing points and distribution branches.
• Auxiliary compressed air networks for pneumatic actuators and control instruments.

Equipment selection criteria

• Design flow rate, minimum flow rate and allowable pressure drop.
• Supply and return temperature of the circuit.
• Operating pressure, design pressure and valve differential pressure.
• Material compatibility with hot water, chilled water, glycol, steam or condensate.
• Isolation, control, non-return, balancing or protection function.
• Valve behaviour at part load and variable flow conditions.
• Automation, modulating control, position indication and fail position requirements.
• Connection to BMS, PLC, DDC controller or local automation panel.
• Access for inspection, section isolation, cleaning and maintenance.

Indicative equipment

• Isolation valves for hot water, chilled water, glycol and steam circuits.
• Two-way or three-way control valves for flow and temperature regulation.
• Balancing valves for hydraulic adjustment of branches and terminal units.
• Differential pressure regulators for stabilising variable-flow circuits.
• Pressure reducing valves and pressure regulators for steam, water and auxiliary lines.
• Check valves for pump protection and backflow prevention.
• Safety and relief valves for boilers, heat exchangers, vessels and closed circuits.
• Steam traps and condensate equipment in steam lines.
• Line strainers for protection of control valves, pumps, heat exchangers and instruments.
• Electric and pneumatic actuators for connection to automation systems.

For each application, the heating or cooling load, flow rate, temperature difference, differential pressure, terminal unit type, available installation length and control logic should be reviewed. These data define the valve type, nominal size, pressure class, construction materials, sealing arrangement and suitable actuation method.