Skill in the installation, repair and maintenance of commercial or industrial HVAC equipment and systems; in the use and maintenance of tools and equipment of the trade; in welding, brazing, soldering; in reading and interpreting blueprints, schematics, drawings, specifications, and contract documents; in the use of dial indicators, vernier calipers, and depth micrometers; in using computers to diagnose HVAC system problems. Work involves the regular, and at times sustained, performance of heavier physical tasks such as walking over rough or uneven surfaces, bending, stooping, working in confined space, and lifting or carrying moderately heavy (20-50 pounds) items and occasionally very heavy (100 pounds or over) items.