Ability to use and interpret diagnostic readings from: volt/ohm meter, amp clamp, manometer, vacuum gauges, combustion analyzer, recovery machine, nitrogen regulator, vacuum pump, vacuum gauge, digital thermometer, air hood, and pitot tube tools. Developing or working knowledge of specialty systems such as building automation, variable refrigerant flow, variable speed drives, variable air volume, gas burners, boilers, humidification, zoning, and zoning controls.