It is spring time in the Rockies once again. Every year I count living in beautiful Colorado as one of my blessings. I love the smell of the air and the way the sun shines in that special way that is halfway between winter and summer. The mountains are still covered with snow and the flowers and trees are blooming all around. Everything seems brand new. Especially when the first air conditioning calls start coming in.

It always seems that no matter what, I’m never as prepared as I want to be for those first AC calls. I decided to do something about that this year.

I have created a special full day Air Conditioning training seminar coming to the Denver area April 25th and in Colorado Springs May 2. Come and join me for the day and dust the cobwebs off your air conditioning service skill set. Go to to learn more details.

Lots of technicians find that spring is a great time to get new tools or test instruments; especially after you dig out your old refrigerant manifold and use it for the first time. Technicians ask me all the time about digital manifold sets and what I think of them. Sounds like a great topic for an article.

Digital manifold sets have been around for a number of years. Now, there are more available than ever before. Yellow Jacket, Fieldpiece, CPS, Refco, and Testo are some of the best known brands available. Each maker offers different levels of features at different price points. All of them feature LCD readouts instead of dial type gauges. All have thermometers for measuring liquid and suction line temperature. All feature built in P/T chart information for many different refrigerants. All of them will display operating subcool and superheat directly.

Digital refrigerant manifold sets are great for two reasons. 1: they offer generally excellent accuracy. Because of their digital displays, it is easy to tell the difference between 395 psig and 397 psig for example. 2: Because of their built in P/T charts and built in thermometers, they can easily display running superheat and subcool numbers simultaneously. Measuring and interpreting superheat and subcool values are both very important and these tools make this process easy. Easy often means more likely to actually happen and that will lead to more accurate and faster system analysis. This is a trend I am very much in favor of.

Some models even feature built in micron gauges for measuring the level of vacuum when evacuating systems. All of these features combine to help make it easier for technicians to be more accurate and more precise when doing air conditioning and refrigeration work. This is a very good thing.

Now for the negatives: First is cost. These puppies get to be pretty expensive. I do believe, however, that with the combinations of features and durability they all offer that they are worth the price. Second is ruggedness. Personally, I’m pretty hard on my gauge sets and all tools in general. My gauges bounce around in the back of the truck, get left out in the rain and snow, and generally get abused. I like being able to replace gauge dials and other individual parts as necessary. With the digital gauges, repairs are usually limited to replacing hoses or sending the unit back to the factory. Third, is weight and bulk. Compared to a simple two valve brass manifold, these digital gauges are downright heavy and clunky.
Finally, one other factor to consider with digital gauges is trustability. Good dial gauges that are properly applied can be trusted because the gauge needle is directly physically connected to the pressure source. Digital gauges, by contrast, have an electronic transducer that converts pressure into an electronic signal. That signal goes to a computer brain that “thinks” about the signal and decides how to interpret and convert that signal into an LCD readout. This process, while usually very accurate, also presents many opportunities for internal faults and error. One system that overcomes this limitation is the Hilmore set. This set combines all of the features of a digital 4 valve manifold with a pair of dial type pressure gauges.
On the other hand, one major advantage of some of the more costly digital manifolds is the ability to save readings and then export them to a PC or a printer. This gives indisputable documentation in applications where this is needed. The technician tasked with doing a new construction startup of 100+ water source heat pumps in a new elder care facility or apartment complex will certainly benefit from that.
Final analysis: Digital manifold sets make for a great investment in quality and accuracy, but I wouldn’t want one to be my only gauge set. Don’t throw away your old dial set just yet. You may want them if your digital set starts acting up on you.


So, what do you think about digital gauge sets? Add your comments below.

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