If your line of work is HVAC repair and maintenance, you should have a portable handheld infrared thermometer in your tool kit. Temperature control is your profession and you have to be able to accurately measure it. Speed and accuracy matter whether the job is big or small. An infrared thermometer with a pistol grip and laser aiming device can take accurate temperature measurements in hard to reach areas. Places like duct work in tight ceiling spaces and compressors mounted on a roof. They quickly give you a reading on supply and return air temperatures and read surface temps on a hot pipe.
Here are some other uses:
Scan walls and ceilings for temperature differences in a room
Scan duct work to quickly locate leaks or poor insulation
Measure the flue temperature in a furnace.
Locate coil sweating on condensate lines.
Locate leaks in a steam line safely with out ever touching the steam line
If your job is HVAC work, a moderate investment in a handheld infrared thermometer will more than pay for itself over time.