By Roy Collver
Every technician has a wish list of tools that they know will help them do a better, faster, and more accurate job. High on these lists should be reliable and accurate diagnostic test instruments. Sometimes you may not even know what you need until you hit the troubleshooting wall and realize you are unable to figure something out due to a lack of information. I have most of the tools on my list, but there are always more that would be nice to have—ask any technician’s spouse.
Study the specifications for any instrument you plan on using—it is the first thing to look at after you have checked out the features. Any measurement device works best when it is purposely designed for a certain application, and it is important to pick one where the required measurements are roughly in the middle of the range for the device. It is also necessary to check the level of precision required so the readings you get are actually useful. Establishing an order of priority for purchasing test instruments will vary depending on the type of work you are doing. You will only buy some when the need arises, but there are some that are mandatory for safety and efficiency reasons, and you should get them while you are still in training.
Keep in mind that electronic instruments will need battery changes or charging, so always keep some spares with the tools, and buy an inexpensive battery tester to make sure your spares are still in working order. Electronic instruments are subject to physical damage, water damage, extreme temperatures, and out-of-range damage. Additionally, ongoing costs may add to your annual tool budget, and software may even go out of date, requiring updates. Regular calibration (sometimes requiring a mandatory certificate) might also be needed. Check the owner’s manual carefully so you know how often required service is due.
Evolution of testing
The innovation in instrument technology in the last 20 years has been astounding and the options almost endless. Wireless sensor probes, data logging functions, smartphone compatibility, and digital everything—lots of very cool stuff to spend your money on, so be careful not to go overboard (unless you just have to have it). Remember you are buying professional tools and they should be designed for reliability, accuracy, and toughness. Expect to pay a premium, but expect them to last a long time even though they will see rough service and abuse. I still have my first clamp-on Amprobe. It has been beaten up for over 40 years and still works flawlessly.
The first part of this article covers the specialized instruments needed for servicing hydronic and HVAC heat sources. This is a changing landscape as the industry is pressured to decarbonize our building stock.
For this, I mean gas pressure measuring equipment. Accurate gas pressure measurements are mandatory if you are working with natural gas or propane equipment. A favourite of mine is my 16-inch slack-tube manometer. Considered by some to be a low-tech, or rather “old school”, instrument, this classic tool is the perfect choice for measuring appliance gas pressures between zero-inches water column (WC) up to 16-inch WC (around half-PSIG).
I do have to admit that the many fine digital manometers and pressure testing instruments can be more practical for most everyday service work. My digital manometer is a brilliant example of the many choices available from a variety of manufacturers these days. It has a wide pressure range (-60-inch WC to +60-inch WC)—very high accuracy and fine resolution. It can measure differential pressure and has a number of scales, so you seldom have to do conversion math (WC, mBar, Pa, PSI) and has hold and min/max functions. This type of manometer is precise enough at low pressures to use for duct air pressure measurements (airflow with the right accessories), filter pressure drops, HRV balancing and more. Unless higher pressure measurements are needed, this is likely the only type of gas pressure instrument you will need to start with. As your HVAC career evolves, you will find yourself looking at other test instruments to add to your fleet—Magnehelic gauges for different pressure ranges, multi-channel data loggers, and even chart recorders. It all depends on what you get yourself into.
Oil burning equipment set-up and service require pressure gauges that measure oil pump output pressure and suction pressure. A dedicated draft gauge is handy to have, but you may be able to use your electronic manometer if it is accurate at lower negative pressures.
For flue gas measuring equipment, another mandatory instrument would be a combustion analyzer that is suitable for the fuel you are burning. Flue gasses need to be tested to check the efficiency of the combustion process, and to check the level of hazardous gasses (CO, NO, NO2) being produced. Regular calibration of these instruments will be required, so factor the cost (including a calibration certificate) into your purchasing decision.
All of the electronic combustion analyzers I have used could measure and display CO content in flue gas readings, but what about room air? A dedicated CO measuring instrument, or a multi-gas device that includes CO, should be a part of everyone’s kit. Don’t cheap out and try to use a household CO alarm, they lack the precision of a proper measuring instrument. This is serious business.
Instruments for Heat Pumps
The trickle of heat pumps being installed for hydronic applications will soon turn into a flood. Ground-to-water, water-to-water and air-to-water appliances are all types of geo-exchange heat pumps used for hydronic heat sources. In some jurisdictions, fuel-burning appliances are being banned in new construction and phased out in existing buildings. If you are active in hydronics today (or any part of the HVAC/R industry), you had better get up to speed on refrigeration equipment. That means getting sufficient training to avoid harming yourselves, others, or the equipment you work on. If you are going to be hands-on, you will be required to get whatever level of trade qualification is needed in your jurisdiction, and you will have to get the right equipment. This is a long-term proposition but will position you at the front of the pack when you become qualified, and you should be able to pick and choose your work.
Refrigerant pressure measuring
Refrigeration technicians must have a set of refrigeration valve manifold gauges both for diagnostic testing and for charging. Depending on your level of expertise and how deep you dive in, you may also need a refrigerant leak detector, vacuum pump, refrigerant recovery system, refrigerant weigh-scale, or a micron vacuum gauge. Don’t go out and get any of this stuff until you have a need for it and have been properly trained.
I can’t stress enough the importance of finding a local supplier who is knowledgeable and stocks a wide variety of test equipment and accessories. Often you only need to look to your local wholesaler, but expertise in this area will vary widely from branch to branch. Many branches will have an enthusiastic person in-house that loves to talk about test instruments, knows which ones are best for your application, how to use them, and can teach you some of the tricky bits. They also understand the limitations, know where to get specialty accessories, can service them or send them away to be serviced, and can pick up the phone to the instrument manufacturer or representative to get quick answers when needed. They might even have the equipment to try out or rent when needed.
Online suppliers are also clamouring for your business, but one has to ask the following: will the equipment need regular service? Will you need to purchase consumables? Who will look after it if something goes wrong? What do you do if it doesn’t meet your expectations?
I haven’t even started to talk about electrical test equipment, temperature measurement or specialized hydronic testing equipment, so stay tuned for Part 2, when we take a deep dive into those topics and more.
WARNING: Hydronic/HVAC equipment can be dangerous. This article is written for technicians in training and those that have been trained and qualified to install and service various types of HVAC equipment. It is not intended to instruct unqualified individuals.