Chiller & Cooling Tower Calculator

Inputs

• Peak cooling load in TR (10 to 2,000)
• Diversity factor — 0.85, 0.90 or 1.00 (no diversity)
• Redundancy — N (no standby) or N+1 (one standby)

Method

1. Design capacity = cooling load × diversity factor.
2. Without a standby, selects the next standard chiller size at or above the design capacity from 10, 20, 30, 40, 50, 75, 100, 150, 200, 250, 300, 400, 500, 600, 750 and 1,000 TR, with as many units as the capacity needs; above 1,000 TR it rounds up to the next 50 TR. With N+1, selects the standard size at or above half the design capacity and specifies three units — two carrying the load, one standing by.
3. Cooling tower = 1.25 × design capacity, the allowance for heat rejected above the cooling load itself.
4. Chilled-water flow = 2.4 US GPM per TR and condenser-water flow = 3 US GPM per TR, converted to m³/hr at 0.227.
5. Chiller electrical input = 0.65 kW per TR of design capacity.

Assumptions

• The diversity factor is the user's judgement of how much of the connected cooling load peaks at the same time; the tool does not derive it.
• The flow ratios correspond to a 10 °F (about 5.6 °C) temperature range across the chiller and the condenser; a different range changes the flow.
• 0.65 kW/TR is a planning figure for full-load chiller input; the real figure depends on the machine, the leaving-water temperatures and how much of the year the plant runs at part load.

Limitations

• The cooling load itself is not calculated — it comes from a heat-load study, or a first figure from the AC tonnage calculator.
• No part-load (IPLV) analysis, air-cooled versus water-cooled selection, or pump-head calculation.
• Standby philosophies beyond N+1, plant-room size and cooling-tower siting are outside the tool.