How to correctly size a Chiller

Simple instructions to assure proper cooling for your Industrial application

The importance of selecting a correctly sized chiller cannot be downplayed. An undersized chiller will always be a problem– never able to properly cool the process equipment. An oversize chiller will never be able to run at it’s most efficient level. Identify the correct size chiller and rely on years of continuous, efficient cooling for your application. If you would like help, feel free to give us a call. We do this all the time.

  1. Calculate the ‘delta T’, the change in temperature, between the inlet and outlet water. Measuring the ‘delta T’ requires a thermocouple or thermometer. Check the water temperature of the water inlet line and the water outlet line, and subtract the numbers to compute how much heat the equipment is adding to the water.
  2. Rate of flow in gallons per minute (GPM). To measure the flow rate of the water place a flow meter on the outlet line of your equipment. If one is not available, simply measure the time it takes for the outlet flow to fill a five gallon bucket, and then compute your gallons per minute (GPM) of flow.
  3. Now that you have these two figures, calculate how many BTU’s (British Thermal Units) your equipment puts off.
# BTU/ hour = 500 x GPM x Temperature Difference (delta T)

Repeat this for all the equipment you have, and add up the total BTUs. Now that you have the BTUs, compute the total tons of cooling you need from a chiller.
For example, 1 Ton of cooling is 12,000 BTU/hours

# Tons = (BTU/hr) / (12,000)

This is the size unit you should need. There may be other circumstances, like planning for expansion, that would lead you to buy a different size unit.

Part 1: Determine the BTUs of cooling your process requires

Warning: It is very important that you do not guess at any of the numbers you are providing. A difference of just one degree in temperature could give you the wrong system.

Other things to consider when choosing a Chiller:

Make sure you compare apples to apples!

    • Is the chiller ARI Rated?
      • The ARI (Air Conditioning and Refrigeration Institute) sets the national standards for how to rate BTU’s in the chiller industry, just as UL (Underwriter’s Laboratories) sets the standards for the electrical industry. The ARI National testing standard is 44°F chilled water, tested at 95°F ambient temperature. Some chiller manufacturers rate their chillers at their own standards of 50°F or higher chilled water temperatures.
    • Is the system Contaminate Free?
      • Having a contaminant free “closed loop” system will increase your chiller’s efficiency and lengthen it’s life.

Why a Chiller?
The quality and reliability of a chiller will protect your capital equipment investment, improve productivity, and save you considerable downtime & money. We are proud to provide superior water chillers (standard and custom) that meet a variety of cooling applications.
When you consider the savings in water, sewage, and equipment costs, a chiller makes good business sense and positively effects your bottom line.