As a refrigeration technician, how important is an understanding of basic mathematical relationships? In my opinion, very important. It makes a technician a better technician.

There are many times we, as technicians, rely on math to help us understand the operation of an HVAC system. We use it to properly size and install equipment and, many times, troubleshoot common problems. We don’t need to be math scholars, but we do need to be able to understand basic mathematical principles and solve equations. We need to know how to work with fractions, decimals, squares, and square roots. Understanding algebra, geometry, and trigonometry is also extremely beneficial. Algebra can help us rework a formula to solve a problem. Geometry and trigonometry can help us install equipment more precisely by allowing us to work with slopes and angles.

Being able to accurately add and subtract fractions is essential when it comes to installing systems. The simple process of reading a ruler and adding or subtracting dimensions is important. Not being able to add fractions with different denominators, such as 15 ½ inches and 25 3/8 inches, to determine the amount of pipe to cut can lead to wasted material and a sloppy install. Knowing how to calculate areas and volumes can help us order the right material for a job. Understanding and being able to use the Pythagorean theorem, or the right triangle formula, (c2 = a2 + b2), can also be useful during an installation.


When it comes to sizing equipment, knowing the following basic heat formulas can help to determine the design load of a new install:

• Q Total = U x area x temp differential for heat transmission loads

• Sensible heat = pounds ÷ hours x specific heat x temp differential

• Latent heat factor = pounds ÷ hours x latent heat

• Heat of respiration = pounds x heat of respiration factor

When it comes to troubleshooting, being a good math student can be equally valuable. Being able to covert from PSIG to PSIA and then calculating the compression ratio of a compressor can help determine if a compressor is working outside its normal operating range. When reading some manuals, you may need to convert from Celsius to Fahrenheit to better understand the operation of a system. Being able to convert pressure from one unit to another unit — for example, from inches of mercury to microns — can be helpful.

In a pinch, when you may need to wire capacitors together to get the right capacitance for a motor, knowing the formulas for capacitors in series (1/CT = 1/C1 + 1/C2 + …) and in parallel (CT = C1 + C2 + …) can help you get the motor up and running. Knowing Q = 500 x gpm x T = Btuh can help while troubleshooting the operation of a water-cooled condenser.

With today’s technology, such as smartphones and tablets, doing the math can be much easier, but technicians still need to know how to use these formulas and equations and what they mean. So, the next time someone tells you math is not part of our trade, ask them to calculate the volumetric efficiency of a compressor.

Publication date: 5/9/2016

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