AL HVAC case studies
AL HVAC · Put your knowledge to work in context.
The Alabama HVAC Contractor Licensing Examination is the qualifying exam used by the state's licensing authority to evaluate whether an applicant has the technical and business knowledge expected of a heating, air conditioning, and refrigeration contractor. It is intended for people seeking contractor-level licensure - typically experienced technicians, business owners, and installers moving from hands-on trade work into company-level responsibility - rather than for apprentice certification. The AL HVAC case studies are 5 cases and about 3,725 words.
1High Subcooling, High Superheat on a TXV System
A 3-ton R-410A residential split system with a TXV metering device serves a house where the owner reports the unit "runs all day but the house sits at 78°F." Conditions at the call: outdoor 95°F DB, indoor 75°F DB / 63°F WB, clean filter, blower on high speed. Measured values: suction pressure 100 psig, suction line temperature 55°F at the service valve, discharge pressure 335 psig, liquid line temperature 82°F at the condenser outlet and 68°F at the outlet of the filter drier.
648 words, about 3 min2Heat Pump That Won't Hold Temperature at 25°F
A 2.5-ton single-stage R-410A heat pump with a 10 kW electric strip kit (two 5 kW banks, each on its own 30 A breaker) serves a house in north Alabama. Outdoor design is 22°F; today it is 25°F with wind.
836 words, about 4 min3Excess Static Pressure on a 3-Ton Air Handler
A 3-ton R-410A system with a TXV, a PSC blower rated 1,200 CFM at 0.50 in. total external static pressure, and a 12 SEER-era air handler serves a 1,700 sq ft house.
733 words, about 4 min4Compressor Trips the Breaker: Motor or Circuit?
A 3-ton single-phase scroll condensing unit, 208/230 V, nameplate RLA 16.7 A, LRA 96 A, MCA 21.7 A, MOP 35 A. It is fed by a 40 A breaker through what appears to be 10 AWG copper, roughly 60 ft from the panel.
761 words, about 4 min5Rule-of-Thumb Sizing in a Humid Climate
A 2,000 sq ft single-story house built in 1994 near Huntsville, Alabama. Design conditions are 95°F DB / 75°F WB summer and 22°F winter.
747 words, about 4 min