HVAC System Design 4

Question 1

When sizing a refrigerant suction line, the primary concern is avoiding excessive:

Accepted Answer

Pressure drop that reduces compressor capacity

Answer

Excessive suction line pressure drop lowers suction pressure at the compressor, reducing capacity and efficiency, and can cause liquid refrigerant slugging.

Question 2

What is the 'effective length' of a duct fitting used for in duct design?

Accepted Answer

The equivalent straight duct length that produces the same pressure drop as the fitting

Answer

Effective length (or equivalent length) converts the pressure drop of a fitting into an equivalent straight duct length to simplify total system friction calculations.

Question 3

In a chilled water plant, what does 'delta T' (ΔT) across the cooling coil represent?

Accepted Answer

Temperature difference between entering and leaving chilled water

Answer

Chilled water ΔT is the difference between return water temperature and supply water temperature, typically designed at 10–12°F for optimal plant efficiency.

Question 4

Which system type is best suited for a large open-plan office requiring individual occupant control without ductwork to each desk?

Accepted Answer

Underfloor air distribution (UFAD) with floor diffusers

Answer

UFAD systems deliver conditioned air through raised-floor diffusers near occupants, offering flexible zone control and good air quality without overhead ductwork to every work area.

Question 5

The Coefficient of Performance (COP) of a heat pump in heating mode is always:

Accepted Answer

Greater than 1.0 because it moves heat rather than generating it

Answer

A heat pump's heating COP exceeds 1.0 because it moves (transfers) heat from outdoor air into the building, delivering more energy as heat than it consumes as electricity.

HVAC Practice Test

HVAC Practice Test

HVAC System Design 4