Modern AC/R Service and The Contractor’s Bottom Line

Doug Lockhart, A.Sc.T, Independent Contractor Founder, Digi-Cool Industries

AC/R contractors everywhere are facing increasing pressures to be more productive. Rising labor rates, more legal requirements and stiff competition require productive staff and innovative management. With the current trends in technician certification, these demands will only increase. Armed with the proper tools and knowledgeable staff, the savvy contractor can overcome these challenges, while improving their competitiveness and customer satisfaction. Refrigeration systems often support perishables vital to your customer’s business. The contractor becomes a vital link to their customer’s success, similar to electric and telephone utilities. Compared to install and maintenance, repairs are most demanding because they are unpredictable and not planned for. Contractor responsiveness and efficiency is key. Responding quickly and effectively to a customer’s crisis can directly lead to repeat business and recommendations. For the same reasons, repair work is also challenging to manage in terms of costs and customer satisfaction.

While electrical wiring and air circulation continues to be a source of headaches, more problems in today's refrigeration systems are within the refrigerant circuit. The chemistry between the new exotic refrigerant blends and oils is relatively new to the entire industry, causing more unexpected incompatibilities and service mistakes. Jim Rutz of Tecumseh Products recognizes that many uninformed technicians may have dropped R410A into R22 systems! As a result of service mistakes due to inexperience, many systems can develop toxic brews in their refrigerant circuit. A thorough diagnostic is often needed to make sure these problems are found on the first service call.

Technicians often use wallet P/T cards in working with new blends, which requires manual math calculations to interpolate table entries. Sometimes, they use P/T correlation to identify or confirm the refrigerant in the system. This process is mistake prone and not precise enough to distinguish between similar replacement blends, possibly leading to accidental refrigerant mixing.

Bourdon tube pressure gauges, at 2-3% accuracy, do not have the precision necessary to allow technicians to make accurate, timely or financially prudent decisions about system performance. They sometimes misrepresent the actual reading by adding their own oscillations or damping useful dynamics. Sometimes technicians head in the wrong direction with poor diagnostic information, only to have to return later to re-evaluate their work and explain the previous debacle in parts and labor.

A/C systems often get very little attention to their subtle problems until they become compressor failures. But R22 systems have the highest compressors failure rates! Many refrigerants contain the element fluorine in its structure. In the presence of minute amounts of moisture and air, reactions creates hydrofluoric acid, capable of eating through glass. Since motor windings are silica based, their insulation is extremely vulnerable.

In prevention, subtle problems such as liquid floodback from a plugged evaporator coil, high superheat from plugged condensers, or short charged systems must be spotted early on and consistently. Again, these problems are difficult to see using Bourdon tube gauges.

Fortunately, modern electronic tools already available can address these shortfalls by providing accurate pressure readings, in an easily readable form for the capable technician. Other important features include precise real-time saturated suction temperature (SST) displays, clear display of pressure dynamics useful in diagnostics and tuning, vacuum display, and durability in field use. They all combine to make diagnostic work quicker and more accurate, with less chance of human error.

Precise view of the pressure fluctuations allows technicians to

quickly spot out-of-envelope operating conditions and the exact nature of the problem. Symptoms such as a dirty condenser/evaporator, TEV hunting, or small amounts of liquid floodback, typically difficult to find with Bourdon gauges, all have small sub-psi pressure fluctuation patterns. With the right tool, these patterns are clearly seen, so your technicians make the proper repair right away without guesswork.

An integrated vacuum and pressure gauge is handy for everyday trouble shooting. Typically, readings in inches of mercury are sufficient. A micron vacuum gauge should be used when eliminating moisture or checking for system leaks using a deep vacuum draw.

Automatic SST display eliminates one error prone step of the important superheat calculation. Further, after refrigeration substitution, even drop-in replacements like R407C for R22 requires some metering adjustment. Sometimes neglected by the substituting technician, the 5°F of superheat difference is significant and easily missed by subsequent service workers. If the technician sees the small SST change, he would make the adjustment and the compressor may be saved from seizing or burnout. These situations are similar across different applications, from residential to commercial rooftops to supermarkets.

Finally, do not underestimate the visual image of your firm in your customer’s mind. Combined with professional, courteous staff, the use of modern, well-kept tools leaves a positive impression about your professionalism, helping them remember you the next time they need service.

Refrigeration systems today are vastly different to those with the classic refrigerants from years ago. Technicians need the proper tools to speed up installation and troubleshooting, to offset the extra information and possibilities to consider. These needs can be met with modern, accurate tools that give superior information quickly, such as the Digital Refrigeration System Analyzer (DRSA) from Digi-Cool Industries. Similar to investments in information technology and communication, business owners need to invest in tooling to remain competitive in the changing service landscape.

References:

Big Easy hosts wholesalers: change is the theme

http://www.snipsmag.com/CDA/ArticleInformation/features/BNP_Features_Item/0,3374,20082,00.html

Using Smart Tools in HVAC/R

Doug Lockhart, A.Sc.T, HVAC/R technician Founder, Digi-Cool Industries

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 gas are they running inside 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 R407C gives 45° dew. But the card only has values for 40° and 50°, so you have to take a guess. Or do you say that 76psi you remember for R22 is close enough, since you are doing a drop-in replacement with R407C for it?

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

The Digital Refrigeration System Analyzer (DRSA) takes care of your headaches. It gives you all the information you need at your fingertips. Mounted on your charging manifold, it’s tough and 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 12, 22, and 502, a low side gauge was all you needed for service. These days, we need accurate information to diagnose more subtle issues. More problems in today's refrigeration systems are within the refrigerant circuit as a result of exotic refrigerants, oils and resultant toxic brews. Traditional Bourdon tube pressure gauges and wallet cards does not give you the precision necessary to make accurate or timely decisions about what needs fixing.

Besides an accurate digital pressure reading, the DRSA has a dynamic offset bar graph. The graph segments naturally shows the changes happening to LS and HS pressure, down to ¼ psi movements. These movements are like a heart beat: a system with problems like a little bit of liquid floodback or a wondering 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 spot problems you never knew were there. There’s also no need to carry wallet cards and make fatal mistakes calculating saturation temperatures. After you select from the 16 refrigerants on board, the saturated suction temperature (SST) or due point at the currently pressure is shown automatically for the low side. The high side shows your bubble point. This allows quick superheat and subcooling calculations.

For example, if you assumed R22 and R407C have identical SSTs above, you would have less superheat than you think. The actual dew point for R407C at the old system pressure of 76psi is 48°, not 45°. The Digi-Cool analyzer tells you right on the screen when you set your pressure, so there’s no guessing around. You would also know that the pressure you actually want to use is 72psi.

Don’t think that’s a big difference? A/C systems usually get little attention to their subtle problems until they become compressor failures. "Why do I need a DRSA with 16 refrigerants on board," you ask? Consider that the highest failure rate of compressors is with R22! Fluorine in refrigerants, with minute amounts of moisture and air, forms HF acid---an acid that eats out glass. Since motor windings are silica based, the motor winding insulation dies. The DRSA shows you subtleties like liquid floodback from a plugged evaporator coil, high superheat from plugged condensers, or short charges, whereas they are extremely difficult if not impossible to spot on a conventional gauge set.

Since it presents accurate, constantly updated SSTs, the DRSA reduce charging times by allowing you to charge based on superheat. With readings in "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.

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 2-year warranty. It’s also simple to use, with a display you can see across the room. They have been tested them in the lab and field, even to withstand a truck’s weight!^* I hardly ever use other gauges.

HVAC/R work is much different nowadays; there are many more factors and possible problems. Business owners demand us to be more efficient and productive to keep their business as well as earn future projects. We can accomplish this with more accurate, time saving tools that give us superior information quicker. No other product provides the accurate, detailed bargraph that the DRSA has, to clearly see the exact problem. One tool provides the information necessary for accurate diagnosis, whether you work with residential A/C, rooftop A/C, supermarkets or low temperature cascade systems. Work smarter, not harder!

Download these technical, informative papers in printable PDF format
Contractor Whitepaper Download
Technician Whitepaper Download

http://www.digi-cool.com/