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Digital vs Analog AC Manifold Gauges Review

valuetesters | July 18, 2018

*** Note: This is a guest post from Valuetesters.com and includes links to products on their own site.

AC manifold gauges are some of the most commonly used tools relied upon by HVAC techs. From measuring refrigerant pressure to performing leak tests and refrigerant charging, they are essential tools for AC diagnosis and servicing.

For many years, these gauges were composed of little more than a brass manifold and two dials. Now, digital gauges with backlit LCD displays are commonplace, but some techs may still be on the fence about making the switch. In this article we’ll compare the two types of gauges in order to help techs in the field make the decision that’s right for them.

In the beginning there were dials and tables

The primary purpose of an analog AC manifold gauge is to accurately measure the refrigerant pressures before and after the compressor. From those two pressure measurements, the HVAC technician can then determine if there is too much or too little refrigerant in the system for efficient and reliable performance.

Of course, the manifold can also be used for other tasks like leak testing and evacuation. Using an analog gauge still boils down to the tech reading the dials to get values, and then performing some additional computation and/or timekeeping in order to get the diagnostic answer he needs.

Also, since the gauge faces themselves display the scales required for each refrigerant, a single gauge set could only be used with a few different refrigerants. This has led to techs buying and carrying around multiple gauge sets in order to be prepared for all refrigerants in use today.

Many technicians perform their jobs quite well with the current analog gauges, so what’s left to be improved?

New Technology, New Benefits

Two advantages are gained when the analog dials are replaced by electronic pressure transducers and digital displays: speed and accuracy. Digital gauges report a definite numeric pressure reading faster than a technician squinting at a needle can. And they can do so with greater precision, even if the analog pressure gauges are just as accurate.

This digitization trend has been steadily occurring in other test equipment: the D’Arsonval movement of analog multimeters used by electricians have long been replaced by Digital Multimeters (DMMs) – ditto for hygrometers and vacuum gauges. In fact, even techs who may insist on analog gauges use digital thermometers for their HVAC temperature readings.

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A good example of a basic digital manifold is the Yellow Jacket 46060 Series 41, a marriage between a simple metal manifold and digital gauges. Its electronics are powered by a single CR123A battery, which will last two years with non-stop operation if the backlight is never used.

The Series 41 also showcases the third major advantage of digital gauges: compatibility with a large number of refrigerants – no dial scales or refrigerant P-T charts necessary. The Series 41 comes pre-programmed with the profiles of 21 refrigerants, eliminating the need to own multiple gauge sets.

New Kinds of Tools, New Workflows

Courtesy of Valuetesters.com

If digital manifolds exist on a spectrum of technology enhancements with the Series 41 at one end. Then at the other end we have tools like the Fieldpiece SMAN460 Wireless 4-Port Digital Manifold with Vacuum Gauge. The SMAN460 is less of a manifold gauge and really more of a complete all-in-one HVAC analyzer. Products like this make the decision of choosing between sticking with analog gauges or adopting digital gauges a bit more complicated because the electronics that pave the way for comprehensive tools like the SMAN460 in turn enable new workflows for techs. It’s not a simple apples to oranges comparison.

For example, the SMAN460’s default library of 45 refrigerant profiles can be increase by uploading additional ones through the manifold’s USB port, giving it flexibility that the Series 41 doesn’t have. The SMAN460 also features several integrated sensors: dual thermocouple clamps, a built-in micron gauge, a stopwatch, and a rate indicator.

Not only can this manifold convert between different pressure units (bar, mmHg, psi, etc . . .), but it can also calculate the superheat and subcool (both features are included on many digital manifolds). The SMAN460’s wireless connectivity allows techs to monitor testing via a mobile app and to email reports and store logs of test data in the cloud, all while working in another area. Manifolds in this range also have internal data storage and logging, as well as diagnostic software which integrates with the mobile app.

New Equipment Brings Us the IIoT

Courtesy of Valuetesters.com

This integration between the mobile app, cloud, and field service device is an example of what’s known as the “Industrial Internet of Things” (IIoT). The advanced reporting, logging, remote monitoring, and connectivity features of the SMAN460 (and the Testo 550 as well) is just one example of how IIoT will impact the field service industry, including HVAC servicing.

The productivity benefits of high-end digital manifolds like the SMAN460 are clear, but each HVAC technician must decide if the cost of these tools makes sense for their workloads. Techs must also learn to navigate the manifold’s interface, and keep spare batteries on hand. The unit requires six AA’s cells which can supply the SMAN460 with 350 hours of use (without ever using vacuum, the backlight, or its wireless connectivity), which is much less than the battery life of the Series 41.

Courtesy of Valuetesters.com

Not only is the Fieldpiece SMAN460 one of the more sophisticated digitial manifolds, it is also one of the most frequently sold, along with the Testo 550 and Yellow Jacket P51-870. All three of which are available at www.valuetesters.com

For technicians who can benefit from them, the expanded capabilities of digital manifold gauges may well be worth the investment.

About the Author


Valuetesters.com has been offering quality test equipment from well-known manufacturers for over 15 years. They offer a broad range of HVAC, Electrical, Datacom, Telecom and Industrial quality test equipment. With expert product selection advice and competitive discount pricing, ValueTesters.com brings experience and value to its customers with the aim of developing lifelong relationships with customers.

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