NATE Core case studies
NATE Core · Put your knowledge to work in context.
NATE Core is the fundamentals portion of the NATE certification program for heating, ventilation, air conditioning and refrigeration (HVACR) technicians. NATE describes itself as the nation's largest nonprofit certification organization for HVACR technicians, and its site lists counts of 5,113 contractors, 41,759 technicians and 6,124 testing organizations. The NATE Core case studies are 5 cases and about 3,502 words.
1Low Superheat, High Subcooling on a Fixed-Orifice System
Late Friday callback on a 2.5-ton R-410A split system with a piston metering device at the evaporator. Outdoor ambient 96°F; indoor 80°F dry bulb, 67°F wet bulb.
726 words, about 4 min2Compressor Trips on Breaker After Ten Minutes
A 3-ton R-410A condensing unit, 208/230 V single phase, nameplate RLA 16.5 A, LRA 88 A, run capacitor 45 µF ±6%, no start components. Complaint: it cools for about 10 minutes, then trips the 40 A breaker; after 20 minutes it restarts and repeats.
689 words, about 3 min3Brazing a Filter Drier Beside a Standing-Pilot Water Heater
A basement mechanical room, 9 ft by 11 ft with an 8 ft ceiling, contains a 30-year-old R-22 split system with about 7 lb of charge, a natural-draft gas water heater with a standing pilot, and a gas furnace with a draft hood. Both gas appliances vent into a shared masonry chimney.
712 words, about 4 min4High Temperature Rise in a Gas Furnace
An 80% AFUE gas furnace, 100,000 BTU/hr input and 80,000 BTU/hr output, with a blower rated at 0.5 in. external static and a nameplate temperature rise range of 35°F to 65°F.
678 words, about 3 min5Two Gauges, One Verdict: Instruments That Disagree
You are commissioning a 4-ton R-410A split system for a facility manager who wants a signed commissioning sheet. Your new digital manifold reads 128 psig on the low side; your 3-year-old analog gauge set reads 136 psig on the same port.
697 words, about 3 min