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.

2 Responses

  1. I recently moved back here to Colorado from Florida where all you deal with is Heat Pumps and refrigerant problems. I started out with the standard Fieldpiece SMAN3 Digital Gauges and quickly learned to love how quick and easy it was to get the Superheat and Subcool readings and I also used the built in Micron Gauge nearly everyday. Now i have upgraded to the SMAN5 Digital Gauges to pull vacuums even faster with the built in vacuum hose port.
    Words of Advise:
    1. Yes it is easier to tell the difference from 395psig and 397 psig although for technicians just getting into the field it is far better to learn how to read analog gauges before reading the digital gauges so you can tell when the pressures and needles are off to better learn how to diagnose issues and also i believe it should be mandatory for technicians to learn how to calculate superheat and subcool with out our modern technologies. 🙂
    2. I have never had good luck with the Fieldpiece tools and meters concerning durability. The gauges do have the nice rubber case which helps but keeping your ports, hoses, and knobs clean is a must as i have had a couple friends send their gauges back to be cleaned by the factory. I have also had many friends break the blue clips and metal hanger right out of the box so be gentle.
    3. Talk about accuracy! Any Technician, Installation Crew and Company Owner should be getting digital gauges. For the install crew, with the micron gauge and digital pressure display there is no excuse for not getting a good vacuum or missing a leak under a pressure test. For Technicians, with the superheat and subcool readings so easily to get for almost any refrigerant diagnosing or recharging time is cut in half. For company owners, being more accurate and efficient will lessen the amount of call backs.


    1. I couldn’t agree more. Accuracy is definitely a big key in reducing callbacks and that leads to greater productivity. Also, technicians definitely need to learn how to do the measurements and calculations the ‘old way’ in order to be most effective with the modern tools!

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