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Mechanical / HVACaka: water chilleraka: centrifugal chilleraka: screw chiller

Chiller

In Plain English

A large refrigeration machine that cools water used to air-condition buildings.

Definition

A refrigeration machine that removes heat from water, producing chilled water for air conditioning systems. Chillers use the refrigeration cycle—compressor, condenser, expansion valve, and evaporator—to transfer heat from the chilled water to a condenser medium, which is then rejected to the atmosphere via a cooling tower or air-cooled condenser. Common types include centrifugal, screw, scroll, and absorption chillers.

Why It Matters in Bidding

The chiller is often the single most expensive piece of HVAC equipment in a project budget, with long lead times that can drive procurement and schedule decisions during bidding. Estimators must capture not just the unit cost but the rigging, electrical service, condenser water or air-cooled provisions, and startup, and they should flag lead time as a schedule risk because a delayed chiller can hold up commissioning and occupancy.

Example

After the owner accepts a centrifugal chiller spec, the estimator prices the unit, adds rigging and a crane day to set it on the roof, and notes a multi-month lead time so the project team can issue an early release to protect the schedule.

Related Terms

Chilled Water SystemCooling TowerCompressorRefrigerant

Frequently Asked Questions

Common types are centrifugal, screw, and scroll compressor chillers, plus absorption chillers that use heat instead of electricity to drive cooling. Selection depends on building load, available utilities, efficiency targets, and budget. The chosen type affects equipment cost, electrical demand, and the mechanical room or roof space required.
Chillers are engineered equipment that can take many weeks or months to fabricate and deliver. Because the unit is needed for commissioning before occupancy, a long lead time can become the critical path. Estimators flag this so the team can issue an early procurement release or carry schedule risk in the bid.
Beyond the chiller itself, include rigging and crane time, the electrical feeder and disconnect, condenser water piping or air-cooled provisions, vibration isolation, controls integration, refrigerant, startup, and commissioning. Estimators who price only the equipment and miss these installation items routinely come in low on the mechanical bid.

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