Valves for heating, chilled water, condenser and ventilation circuits

In variable-flow systems, isolation valves must provide bubble-tight shutoff so that individual air handling units, fan coils or heat exchangers can be isolated for maintenance without draining the entire circuit. Butterfly valves are the standard choice for risers and plant room headers at DN65 and above; ball valves for DN50 and below, where their compact face-to-face length and quarter-turn operation suit close-coupled connections.

Globe valves serve flow-regulation duty in HVAC circuits: their parabolic plug and seat geometry allows accurate proportional flow control over a wide stroke range, making them suitable for manual or actuated balancing stations. Two-port and three-port globe valves with electric actuators form the standard control valve assembly for AHU heating and cooling coils.

Silent check valves (spring-loaded wafer type) at pump discharge prevent backflow through a standby pump and reduce water hammer on pump stop compared to swing-type checks. Y-strainers upstream of pumps, control valves and meters protect equipment from pipe scale, flux residue from commissioning, and debris from system changes.

Automatic air vents at high points and low-loss headers remove entrained air that would otherwise cause pump cavitation and uneven heat distribution. Expansion joints absorb pipework movement at plant connections, reducing transmitted vibration from pump and chiller units into the building structure.

High-rise buildings require pressure reducing valves to break the static head in tall risers into manageable zone pressures, protecting fixtures rated to PN10 from overpressure in the lower zones. Differential pressure control valves maintain the design pressure differential across circuits in variable-flow systems, preventing runout in near-plant circuits and starvation in remote branches.

Safety relief valves on closed heating and cooling systems provide overpressure protection in the event of boiler, chiller or heat exchanger malfunction, and are a code requirement in most EU jurisdictions.