Digital manifolds can simplify measurements for younger techs and increase speed and accuracy for the seasoned veteran.

Insanity: doing the same thing over and over again and expecting different results. - Albert Einstein, U.S. (German-born) physicist (1879 - 1955).If that quote doesn’t describe the HVAC industry, I don’t know what really does.

On average, seven out of 10 of the air conditioning systems your technicians will service will either have, or be left with, an incorrect refrigerant charge. Now the question to ask yourself is this: Are your techs the ones finding them that way or leaving them so?

Plain and simple, 13 SEER and above is simply not possible without proper airflow and refrigerant charge; yet we are doing what we have always done, expecting a different result.

If we are going to fix the problems we have in this industry, we really shouldn’t use the same tools we used to create them. Analog gauges have brought us to this point, and will keep us here if we let them. Simply, analog gauges cannot do the job as evidenced by the success we have had using them. Not to say all fault lies in substandard instrumentation. I am sure equally as much lies in their use and application.

Air conditioners and other refrigeration systems, however, will run in spite of us. They will use more power straining the grid, fail in warranty, spoil product, and result in countless lost hours of down time, sleep, or service - yet, we will fix them again and again. We will always do what we’ve always done, and always get what we’ve always got, and here the story will end if we let it.

In researching this topic, I ran across an interesting article, “Digital Gauges: A Manifesto.” In regard to its content, I really couldn’t have said it better myself, nor with the passion and conviction. For those that know me personally, you know I always have a bit to add to every conversation, but this article really said it all.


The author of the article started with the following question: “Why a manifesto on the digital manifold gauge (DMG)?” He answered: “Never really thought about it until it was pointed out to me that a manifesto is essentially what I am guilty of spewing forth in my support of the technology and, in most cases, the OEMs that have brought the technology in a viable format suitable for field applications.

“I don’t support the technology for the sake of the technology, impressive though it may be. I support the technology because it’s good for the trade, and just as importantly it’s good for the technician. Digital instruments - and specifically digital refrigeration gauges - offer tangible as well as intangible benefits that are often overshadowed by other issues and discussions that more often than not end in a tangent of pro and con viewpoints on the necessity of the instrumentation.

“Is DGM a necessity in the performance of the technician’s craft? Of course not. Good tires on a service vehicle, digital multimeters, an answering service to professionally answer your telephones after hours - none of that is truly a necessity.

Power measurements made before and after prove that the use of digital manifolds increases the energy efficiency ratio (EER), resulting in maximum equipment output per watt of power used.

“After all, our vans can make it from point A to point B with slick tires. We can validate the presence or absence of voltage or current draw in a circuit with an analog meter, even if it isn’t a Simpson. And, we can either let the phone ring until the client gets tired and hangs up or we can hook up an answering machine for clients to talk to. While they may be considered non-necessities, they are components in our daily business that contribute to our appearance as professionals.

“Just as surely as a clean, waxed service vehicle and clean cut, shaved technicians in uniform with shoe covers (and without a cigarette hanging out of their mouth) contribute to the service organization’s overall appearance of professionalism, so, too, do the tools and instruments they bring to the door.

“This is one of the intangible factors. It isn’t something you can actually invoice and collect from the client in the strictest sense of the word, but it is something you will ultimately take to the bank. Aside from the obvious prerequisite of knowing the trade - being a skilled craftsman - professionalism is bred by actions, methods, and means. Better tools make a better technician, and a better technician equates to a more professional technician.

“The DGM is the means to more accurate, effective methods that leads to confidence in the technician’s own skills, which is further reflected in his actions.

Using a digital manifold, a technician can charge directly by superheat or subcooling, eliminating the need for temperature pressure charts, while reducing errors. Results can be printed for documentation, also.


“One of the favorite arguments of the technician or business owner against the DGM is the cost. I don’t have much in the way of a publishable comment to those technicians/business owners, nor will I waste a lot of my time or space here to address that type of thinking. It breaks down very simply. If you are an average technician, you are using at least two analog manifold gauge sets, usually one for R-22 and one for R-410A.

“More often than not, these need to be or at least should be replaced once a year, unless of course you intend to send them in for calibration once a year at a cost that would be higher than replacing them. One DGM replaces dozens of gauge sets just based upon onboard refrigerant profiles alone. The DGM is an investment. No question about that. Just the same as a quality DMM or combustion analyzer, they are not free. So if you are expecting to invest in one for the same cost as a Radio Shack needle meter, you’re in the wrong place.

“If the cost is the sole obstacle to any technician or business owner stepping into the 21st century with refrigerant circuit analysis instruments, take the cost off your taxes or take some of the old equipment your installers removed, down to the local scrap yard. Whatever you do, just stop whining about the cost of the investment. It’s an argument that has no merit.

“The biggest single obstacle though, as far as the DGM being widely accepted by the technician community, is a legitimate issue. It’s deep-rooted and it’s double-pronged. One side of this fork is tradition. The Bourdon tube analog gauge, that we are all so familiar with and is an admitted icon of the trade, has been in use and essentially unchanged in the past 75-plus years. Plain and simple: old habits die hard. Real hard.

“Another component is the simple reality that people don’t like change. It’s uncomfortable. You have this preconceived apprehension of what will almost certainly be a required learning curve, a learning curve that is non-existent with today’s digitals. They are exceptionally intuitive. The transition to the DGM and away from the analog manifold gauge is inevitable, just as it was with the multi-meter and the combustion analyzer. There will be holdouts, just as there were and are with combustion analyzers and multi-meters. But they won’t alter the inevitable.”

Enough said. Go digital.

Excerpted from and edited for length. Used with permission.

Publication date:06/02/2008