Digital Zeus™ HVAC Tool & Instruments Journal

the Digital Gauge Manifold Manifesto

American Heritage Dictionary -

man·i·fes·to (mān’ə-fěs’tō) Pronunciation Key n. pl. man·i·fes·toes or man·i·fes·tos A public declaration of principles, policies, or intentions

Why a Manifesto on the Digital Manifold Gauge [DMG - hereto after]. 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 OEM’s that have brought the technology in a viable format suitabe 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. The instrument offers tangible as well as intangible benefits that are often over shadowed by other issues and discussions that more often than not end in a tangent of pro and con viewpoints on the necessity of the instrument.

So we can start there. Do I think the DGM is a necessity in the performance of the technicans craft? Of course not. Good tires on a service vehicle, digital multi meters, an answering service to professionally answer your telephones after hours - none of that is truly a necessity. Our vans can make it from point A to point B with slick tires, sure 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 the phone or hook up an answering machine for them to talk to. Those non-necessities are also components in our daily business that contribute to our appearance as professionals. Just as surely as a clean, waxed service vehicle, clean cut, shaved technicians in uniform and with shoe covers and without a cigarette hanging out of their mouth contribute to the service orginizations overall appearance of professionalism, so to do the tools and instruments they bring to the door. This is one of the intangible factors I mentioned in the last paragraph. 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 technican - a better technican equates to a more professional techncian. The DGM is the means to more accurate, effective methods which leads to confidence in the techncians own skills which is further reflected in his actions.

One of the favorite arguments of the technician or business owner against the DGM is their cost. I don’t have much in the way of a publishable comment to those technicans/business owners, nor will I waste alot of my time or space on this Journal page to address it. It breaks down very simply. If you are an average technican you are using at least two analog manifold gauge sets - usually one for 22 and one for 410A. More often than not these need 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 technican or business owner stepping into the 21rst with refrigerant circuit analysis instruments take the cost off your taxes, take some of the old equipment your installers remove 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 and it’s played - way played.

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 - as I have stated in other written opinions of the technology and the obstacles facing it. The Bourdon tube analog gauge that we are all so familiar with an admitted icon of the trade has been in use and essentially from a mechanical aspect, unchanged in the past 75+ years - and old habits die hard - real hard. Another component to this fact is the simple reality that people don’t like change - it’s uncomfortable, you have this preconcieved apprehension of what will almost certainly be a required learning curve - a learning curve that is non-existent with todays digitals, they are exceptionally intuitive. The second and in my opinion the deadliest of the forks in this obstacle is the instruments predeccessors. Tif and the later Robinair “Electronic Solution”.  The Tif digitals, which are incidentally for reasons I can only offer conjecture on are still available in some venues. Can’t imagine it, but they are. And what’s maybe even worse they are selling them and at $90.-$100.00 to boot. I suppose the cliche, “a fool and his money” is a cliche for a reason. The Tif gauge was piss poor at performing in the role that it was actually desinged for to begin with, a pressure indicator. The Tif was put into the market with little or no fieldtesting support and then when they failed, and then failed again, and again - there was no product support for them. The electronics that were packed in the case ie., wafer board and transducers were not suited for being mounted on anything not stationary, and they don’t perform consistently on stationary applications either. They were a strike out from their inception and are in my opinion single handedly responsible for as much as a 15 year delay in the introduction of the technology in a viable conveyance capable of withstanding the demands of field use. The Robinair, [who oddly enough is a sister company to Tif - both having SPX as their corporate parent] version was actually headed in the right direction of actually obtaining a valid designation as a digital manifold gauge. I’ve reviewed the U.S. Patent applications on the 41875 Electronic Manifold Solution - theoretically this was going to be a solid instrument - a couple of things were lost in the translation from design to production. The key two of which were the use of sub-standard transducers in the instrument and the decision to preclude refrigerant profiles from the processor - critical, ill advised decisions, at least in hindsight anyway. The refrigerant profiles were accomplished via dedicated “keys” that were far too easy to lose, and the transducers failed without apparent rhyme or reason. The end result was yet another chapter in the failure to digitize the manifold gauge.

The biggest fault in the continual recital of the failures that are essentially the Tif and Robinair digital legacy, is time. The Tif and Robinair failures were obvious in a very short period of time, relevant to the lapse between introduction and their removal from the counter. That same element of time is also the reason that at least some of the DGM’s should be allowed to overcome the shadow of the Tif/Robinair legacy. This manifesto is not slanted in the direction of any DGM OEM. There are abundant resources available on the internet to help the technician determine the best suited DGM for his particular service applications. With that basic understanding however, no Article or document can be considered complete without pointing out the chronological factor that is relevant to the DGM of today. The chronological consideration is relevant to this Article simply because the true test of this technology is time - how long has it been used in field applications, because it was the same yard stick that determined the failure of Tif/Robinair’s attempts. 

I’ve no intention of engaging in a pissing match over which was first, Digi-Cool® or Testo® simply because for the purpose of this Article it is irrelevant. Both instruments have been used in the field for a significant enough period of time to have validated their respective suitability to field demands. There are for all intents and purposes five OEM’s of the DGM. The first two I mentioned are the forerunners in DGM technology. Each has undergone significant generational revisions to incorporate features that are reliable, accurate and demanded by their users. The J/B®, the Mastercool® and the Refco® are still in their proving ground stages in my opinion. Not because they are inferior, simply because they have not been time tested in field applications. Each set offers varying levels of capabilities with varying levels of investment. Each technician will ultimately be responsible for selecting the set that best fits their needs. But as with anything in life, don’t expect to pay Mastercool® prices for Digi-Cool® or Testo® features and quality - it will culminate ultimately in disappointment.

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 hold outs to the transition just as there were and are with combustion analyzers and multi-meters. But they don’t alter the inevitable.

This manifesto is an open statement of my own opinion(s) on the subject addressed. My opinion is not necessarily reflective of those of any of my professional associates. I reserve the right to modify and edit including making additional statements to this manifesto at my sole discretion. The opinions of the readers of this Journal are both encouraged and welcomed. If you would like to comment on this manifesto, please feel free to forward your comments to digital.zeus@yahoo.com if you would like your comments published to the Journal, please reflect that desire in your comments.