HVAC Ductless Mini-Split Systems

Question 1

What is the primary advantage of a ductless mini-split system over a central ducted system?

Accepted Answer

Elimination of duct losses (typically 20-30% of energy in ducted systems) and ability to serve spaces without existing ductwork

Answer

Lower initial equipment cost

Answer

Higher cooling capacity per outdoor unit

Answer

Simpler refrigerant circuit with fewer components

Question 2

What does 'inverter-driven' compressor technology in mini-splits provide?

Accepted Answer

Variable-speed compressor operation that modulates cooling/heating capacity to exactly match the load, improving efficiency and comfort

Answer

The ability to invert DC to AC power for the outdoor fan

Answer

A built-in power inverter for backup electricity

Answer

Inverted refrigerant flow for improved heating mode

Question 3

What is the typical line set for a ductless mini-split system?

Accepted Answer

Refrigerant lines (liquid and suction), electrical power/signal wiring, and a condensate drain line

Answer

Gas line, electrical conduit, and water drain only

Answer

Only refrigerant lines — electrical is separate

Answer

A pre-charged sealed line set that cannot be extended

Question 4

What is the maximum typical line set length for a standard residential ductless mini-split?

Accepted Answer

50-75 feet (15-23 m)

Answer

15 feet (4.5 m)

Answer

25 feet (7.6 m)

Answer

200 feet (61 m)

Question 5

What is a 'multi-zone' mini-split system?

Accepted Answer

One outdoor unit connected to multiple indoor units (2-8 zones) via individual refrigerant branch piping

Answer

A system with multiple outdoor units each serving one indoor unit

Answer

A system that can heat and cool multiple buildings simultaneously

Answer

Multiple mini-splits installed in the same zone for redundancy

Question 6

What is the minimum ambient operating temperature for most standard heat pump mini-splits in heating mode?

Accepted Answer

17°F (-8.3°C)

Answer

-22°F (-30°C)

Answer

32°F (0°C)

Answer

5°F (-15°C)

Question 7

What type of indoor unit is most commonly used in residential ductless mini-split installations?

Accepted Answer

Wall-mounted high-wall unit

Answer

Ceiling cassette (four-way blow)

Answer

Floor-mounted console unit

Answer

Ceiling-concealed ducted unit

Question 8

How is the refrigerant in a mini-split system typically charged at installation?

Accepted Answer

Pre-charged at the factory for standard line set lengths; additional refrigerant is added only if line set exceeds the standard length

Answer

Charged by weight based on line set length

Answer

Always charged in the field after installation by the technician

Answer

Charged with nitrogen from the factory and replaced with refrigerant on-site

Question 9

What is the purpose of the 'auto-restart' feature in mini-split systems?

Accepted Answer

Restarts the system automatically after a power outage, returning to previous settings

Answer

Restarts the compressor after a fault without requiring manual reset

Answer

Automatically restarts cleaning mode after 1000 hours of operation

Answer

Restarts the defrost cycle if the first cycle fails to clear ice

Question 10

What is 'heating mode defrost' in a mini-split heat pump, and what causes it?

Accepted Answer

A temporary reverse-cycle operation that melts frost from the outdoor coil when it accumulates during heating mode

Answer

A cycle that heats the refrigerant lines to prevent freezing during cold weather

Answer

A mode that heats the indoor unit coil during startup to prevent condensation

Answer

An electric resistance defrost that heats the outdoor unit base pan