These 5 questions cover air conditioners, heat pumps, condensate and temperature split. On the National Home Inspector Examination they fall under Property Inspection (70% of the exam). Try each one before you open the answer: the explanation matters more than the letter.
1. Which refrigerant replaced Freon (R-22) in residential air conditioning systems?
- R-134A
- R-404A
- R-22B
- R-410A
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Answer: D. R-410A
R-410A replaced Freon (R-22) in residential systems because R-22 had negative environmental effects and has been phased out of production.
Memory tip: R-410A replaced R-22 (Freon) — environmental phase-out drove the change.
2. On a hot day the inspector measures a 20°F drop between return air and supply air at the air handler. This temperature drop occurs at the
- compressor
- evaporator coil
- condenser coil
- expansion valve
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Answer: B. evaporator coil
The evaporator coil absorbs heat from the indoor air passing over it, cooling and dehumidifying the air. A temperature drop of roughly 14–22°F across the coil is typical for a properly operating system.
Memory tip: Evaporator eats the heat.
3. Water is dripping from a secondary drain pan under an attic air handler. The MOST appropriate report entry is
- normal operation of the secondary drain pan
- a blocked primary drain; recommend HVAC service
- a low refrigerant charge in the system
- an air handler that is undersized for the house
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Answer: B. a blocked primary drain; recommend HVAC service
Condensate is water removed from the air at the evaporator coil. It should flow out the primary drain; the secondary pan only catches overflow. Water in the secondary pan means the primary drain is blocked or disconnected and needs service before it overflows into the ceiling.
Memory tip: Secondary pan wet = primary blocked.
4. Where should the evaporator coil NOT be located relative to a furnace?
- Before the combustion chamber
- After the combustion chamber
- Above the air handler
- In the return air plenum
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Answer: A. Before the combustion chamber
An evaporator coil should not be located before a furnace combustion chamber because the moist air from the coil may damage the furnace. It should be on the downstream (supply) side.
Memory tip: Evaporator coil goes AFTER the furnace, never before — moisture would damage the heat exchanger.
5. A client asks why some duct openings have adjustable louvers and others are fixed grates. The inspector should explain that
- the fixed grates are defective and need replacing
- both types of opening should be adjustable
- registers have dampers for supply; grilles cover returns
- the louvers indicate the system is zoned
Show answer
Answer: C. registers have dampers for supply; grilles cover returns
Registers include an adjustable damper for supply air; grilles are fixed openings, usually at returns. Identifying them correctly helps describe the distribution system.
Memory tip: Register adjusts; grille just covers.