Duct Systems
What is the purpose of an extended plenum system?
To reduce velocity and noise at the last takeoffs.
Why are pleated filters better than standard filters?
They have more surface area and clog slower.
What does a higher EER rating mean?
Greater efficiency.
At what temperature does the evaporator boil in a standard system?
40°F
What four factors define comfort?
Temperature, humidity, air movement, and cleanliness.
What is duct pressure measured in?
Inches of water column (in. WC).
What do electronic air cleaners use?
Ionizing sections, charcoal filters, and prefilters.
Which rating considers the full cooling cycle?
SEER (Seasonal Energy Efficiency Ratio).
At what temperature does the evaporator boil in a high-efficiency system?
45°F
What is the solar load?
Heat gain from sun radiation.
What is used to reduce noise and vibration in ductwork?
Flexible duct connector.
What is humidification?
The process of causing water to evaporate into the air.
What are nominal ratings?
Approximate ratings, not exact.
What is the normal evaporator superheat at the outlet?
10°F
What is the recommended humidity range for residences?
40%–60%
What fasteners are used for sheet metal ducts?
'S' fasteners (slips) and drive clips.
What are the steps to aggressively control indoor air contamination?
Source removal, ventilation, and cleaning.
What rating does not account for startup losses?
EER.
What happens if the condenser coil is dirty?
Efficiency decreases.
What is the dew point temperature?
The temperature at which moisture begins to condense.