Heat Load Calculations and System Sizing Flashcards
7 cards from real Air Conditioning Repair practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Heat Load Calculations and System Sizing flashcards as text
What type of heat gain is caused by heat transferring through walls, roofs, and floors due to a temperature difference?
Answer: Conductive heat gain
Conductive heat gain occurs when heat flows through solid building materials from a warm exterior surface to a cooler interior, governed by the material's U-value and the temperature difference.
In the northern hemisphere, windows facing which direction typically contribute the greatest solar heat gain during summer afternoons?
Answer: West
West-facing windows receive direct sunlight during the afternoon when outdoor temperatures are at their highest, resulting in the greatest peak solar heat gain.
What does the latent heat load in an air conditioning system represent?
Answer: Moisture that must be removed from the air
Latent heat load is associated with moisture (water vapor) removal from the air; removing latent heat does not lower air temperature but reduces relative humidity.
ASHRAE design outdoor conditions used in load calculations are based on which statistical criteria?
Answer: A temperature exceeded only 1% of annual hours
ASHRAE design conditions represent outdoor temperatures that are exceeded only 1% (or 2.5%) of all annual hours, providing a statistically reliable but not absolute worst-case design point.
How does uncontrolled air infiltration affect a building's cooling load?
Answer: It adds both sensible and latent load by introducing unconditioned outdoor air
Infiltration introduces hot, humid outdoor air through gaps and cracks in the building envelope, adding both sensible heat (temperature) and latent load (moisture) that the AC system must handle.
What is the primary purpose of an ACCA Manual D calculation?
Answer: Designing and sizing the duct distribution system
ACCA Manual D is the industry standard for residential duct system design, providing methods to size ducts so that the correct amount of conditioned air reaches each room.
In a residential load calculation, what category includes heat generated by occupants, lighting, and household appliances?
Answer: Internal heat gain
Internal heat gain accounts for heat produced by sources inside the conditioned space, including people, lighting fixtures, and appliances such as ovens and electronics.