313D System Installation and Maintenance 2 — Questions and Answers
Question 1: When installing an outdoor condensing unit, what is the minimum recommended clearance from the unit to surrounding walls or fences on the service side?
- 12 inches
- 24 inches
- 36 inches (Correct answer)
- 48 inches
Correct answer: 36 inches
Most manufacturers require at least 36 inches of clearance on the service side of the outdoor unit to allow safe and effective maintenance access.
Question 2: During installation, which type of pipe insulation is most suitable for residential refrigerant suction lines?
- Fiberglass wrap
- Closed-cell foam insulation (Correct answer)
- Open-cell foam insulation
- Rubber pipe wrap tape
Correct answer: Closed-cell foam insulation
Closed-cell foam insulation is preferred for suction lines because it resists moisture absorption and provides effective thermal insulation.
Question 3: When mounting an air handler in a horizontal position in an attic, which direction should the condensate drain slope?
- Upward toward the unit
- Level, with no slope
- Downward away from the unit at a minimum 1/8 inch per foot (Correct answer)
- Downward at exactly 1/2 inch per foot only
Correct answer: Downward away from the unit at a minimum 1/8 inch per foot
Condensate drain lines must slope downward away from the unit at a minimum of 1/8 inch per foot to ensure proper drainage by gravity.
Question 4: What is the primary reason for installing a vibration isolation pad under a residential condensing unit?
- To improve electrical grounding
- To reduce noise and vibration transmission to the structure (Correct answer)
- To increase airflow under the unit
- To prevent frost buildup on the base
Correct answer: To reduce noise and vibration transmission to the structure
Vibration isolation pads absorb compressor and fan vibrations, preventing noise and structural vibration from transmitting into the building.
Question 5: A technician is installing a new split system and must size the refrigerant line set. Which factor is MOST critical when determining the suction line diameter?
- The distance from the outdoor unit to the electrical panel
- The tonnage of the system and the equivalent length of the run (Correct answer)
- The brand of refrigerant being used
- The color of the insulation jacket
Correct answer: The tonnage of the system and the equivalent length of the run
Suction line diameter must be sized based on system tonnage and total equivalent line length to maintain adequate refrigerant velocity and minimize pressure drop.
Question 6: During a new installation, after brazing refrigerant lines, what procedure must be performed before charging the system?
- Immediately charge with refrigerant
- Pressure test with nitrogen then evacuate to a deep vacuum (Correct answer)
- Rinse lines with water to check for leaks
- Run the system dry for 30 minutes
Correct answer: Pressure test with nitrogen then evacuate to a deep vacuum
After brazing, the system must be pressure-tested with dry nitrogen to check for leaks, then evacuated to a deep vacuum (typically 500 microns or less) to remove moisture and air before charging.
Question 7: When anchoring refrigerant line sets to wall studs or joists, what is the maximum recommended spacing between hangers or supports for copper tubing up to 7/8-inch OD?
- 3 feet
- 6 feet (Correct answer)
- 10 feet
- 15 feet
Correct answer: 6 feet
Industry standards recommend supporting copper refrigerant tubing at a maximum of 6-foot intervals to prevent sagging, vibration, and stress on fittings.
313D System Installation and Maintenance 2
When installing an outdoor condensing unit, what is the minimum recommended clearance from the unit to surrounding walls or fences on the service side?