The Digital Refrigeration System Analyzer (DRSA) is shown being hooked up to an outdoor condensing unit.
As a technician, our lives get more complicated every day. We've got legal requirements, customers, management, and even weather to deal with. On top of that, sometimes we have to follow up on iffy work from the previous service. What refrigerant are they running in the system? How many refrigerants do you keep in your truck?

There are lots of useful tools for electrical work: multimeters, current clamps, and wands that light up next to a live wire. To this day, we really can't tell that much about the refrigeration circuit. The pressure gauges in your manifold are coarse, and they can't show the smaller things like sucking small slugs of liquid. Your thermometer tells you the suction line temperature, but you've got to find the right line on your wallet card that tells what pressure for R-407C gives 45 degrees dew point. But the card only has values for 40 degrees and 50 degrees, so you have to take a guess. Or do you say that the 76 psi you remember for R-22 is close enough, since you are doing a drop-in replacement with R-407C for it?

There is no reason why smart tools can't solve these refrigeration circuit problems. That's why I'm excited to share my invention with you.

The Digital Refrigeration System Analyzer (DRSA) helps take care of your refrigerant system headaches. It gives you all the information you need at your fingertips. Mounted on your charging manifold, it's easy to handle. It shows you all the hidden pressure fluctuations you've been missing, saving you time and showing you what is wrong.

In the old days of R-12, -22, and -502, a low-side gauge was all you needed for service. These days, we need precise information to diagnose more subtle issues. More problems in today's refrigeration systems are within the refrigerant circuit as a result of new refrigerants, oils, and resultant toxic brews. Traditional Bourdon tube pressure gauges and wallet cards do not give you the precision necessary to make accurate or timely decisions about what needs fixing.

In addition to a digital pressure reading, the DRSA offers a dynamic offset bar graph, which shows the changes happening to low-side and high-side pressure.

A More Precise Tool

Besides an accurate digital pressure reading, the DRSA has a dynamic offset bar graph. The graph segments show the changes happening to low-side and high-side pressure, down to 1/4 psi movements. These movements are like a heart beat - a system with a problem such as a little bit of liquid floodback or a wandering TEV is easy to spot; a healthy one is obvious. Believe it or not, most people have never seen these important movements. With the DRSA, you will have the ability to spot problems you would have never known were there in the past.

The DRSA enables quicker superheat and subcooling calculations.
With this unit, there's no need to carry wallet cards and make mistakes calculating saturation temperatures. After you select from one of the 22 refrigerants onboard, the saturated suction temperature (SST) or dew point at the current pressure is shown automatically for the low side. The high side shows your bubble point. This allows quicker superheat and subcooling calculations.

For example, if you assumed R-22 and R-407C have identical SSTs above, you would have less superheat than you think. The actual dew point for R-407C at the old system pressure of 76 psi is 48 degrees, not 45 degrees. The Digi-Cool analyzer tells you right on the screen when you set your pressure, so there's no guessing. You would also know that the pressure you actually want to use is 72 psi.

Air conditioning systems usually get little attention to subtle problems until they become compressor failures. (Compressor photo courtesy of Copeland Corporation.)
Don't think that's a big difference? A/C systems usually get little attention to subtle problems until they become compressor failures. "Why do I need a DRSA with 22 different refrigerants onboard?" you ask. Consider that the highest failure rate for compressors is with R-22! Fluorine in refrigerants, with minute amounts of moisture and air, forms hydrofluoric acid - an acid that eats glass. Since motor windings are silica based, the motor winding insulation can be eaten away. The DRSA shows you subtleties like liquid floodback from a plugged evaporator coil, high superheat from plugged condensers, or low charges, whereas these things are extremely difficult if not impossible to spot on a conventional gauge set.

Since it presents accurate, constantly updated SSTs, the DRSA reduces charging times by allowing you to charge based on superheat. With readings in inches Hg, drawing a vacuum on a system for everyday work is simple. However, we recommend a micron vacuum gauge when eliminating moisture or determining the tightness of a system by deep vacuum draw.

The DRSA is a rugged unit and can even withstand a truck’s weight. (Note: Not recommended for users. Similar abuse will void the product warranty.)
As a technician, I know the punishment tools go through. Rest easy that the DRSA is built to last. It's water-resistant, handles bangs around the truck and minor drops, and comes with a two-year warranty. It's also simple to use, with a display you can see across the room. It has been tested in the lab and field, even to withstand a truck's weight! I hardly ever use other gauges.

Work Smarter, Not Harder

HVACR work is much different nowadays; there are many more factors and possible problems. Consumers and business owners demand that we be more efficient and productive to keep their business and earn future projects. We can accomplish this with more accurate, time-saving tools that give us superior information quicker.

The DRSA's detailed bar graph helps you to clearly see the exact problem. This tool provides the information necessary for fast and accurate diagnosis, whether you work with residential A/C, commercial rooftop A/C, supermarket refrigeration, or low temperature cascade systems. It helps you to work smarter, not harder.

Doug Lockhart, A.Sc.T, is an HVACR technician and founder of Digi-Cool Industries Ltd., Duncan, British Columbia. For more information, e-mail or visit

Publication date: 05/31/2004