In Plain English
Quick Answer
A central cooling system that circulates cold water through pipes to cool air in multiple areas of a large building.
Definition
Definition
A central cooling system that uses chilled water produced by a chiller to distribute cooling energy to air handling units and fan coil units throughout a building. Chilled water is typically supplied at 44°F and returned at 54°F through insulated piping. Chilled water systems are preferred for large buildings because they are more efficient and flexible than direct-expansion refrigerant systems.
Context
Why It Matters in Bidding
Chilled water systems are among the most cost- and coordination-intensive HVAC packages on large commercial projects, spanning chillers, pumps, insulated piping, controls, and air handlers, so the mechanical sub's bid hinges on accurate takeoff of these interdependent components. Because the system touches structure, electrical capacity, and roof or mechanical-room space, estimators must coordinate it across trades to avoid scope gaps and costly change orders later.
Example
Example
Pricing a mid-rise office, the mechanical estimator takes off linear feet of insulated supply and return piping, the chilled-water pumps, and the air handling units, then coordinates the chiller's electrical load with the electrical sub before submitting the HVAC bid.
See Also
Related Terms
FAQ
Questions Contractors Ask
When is a chilled water system more cost-effective than a DX system?
Chilled water systems generally win on larger buildings with many zones, where their efficiency, central control, and flexibility offset higher first cost. Smaller buildings often favor direct-expansion (DX) systems because they are cheaper to install. Estimators weigh building size, zoning needs, and operating cost when comparing the two during budgeting.
What components should be included in a chilled water system takeoff?
A complete takeoff covers the chiller, chilled-water pumps, insulated supply and return piping with fittings and hangers, air handling and fan coil units, cooling tower or air-cooled condenser, valves, and controls. Missing the insulation, hangers, or balancing scope is a common source of underbidding on these packages.
How does a chilled water system affect other trades in the bid?
It drives significant electrical load for chillers and pumps, requires structural support for equipment and piping, needs roof or mechanical-room space, and ties into the building automation system. Coordinating these dependencies during estimating prevents change orders and ensures each affected sub carries the right scope.
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