Load Calculation and Blueprints Flashcards

What is the primary purpose of a Manual S calculation in residential HVAC design?

Answer: Equipment selection based on Manual J loads

Manual S uses the Manual J load results to select properly sized heating and cooling equipment for the residence.

On blueprints, what does the scale '1/4" = 1'-0"' mean?

Answer: One quarter inch on the drawing equals one foot in reality

A scale of 1/4" = 1'-0" means every quarter inch measured on the drawing represents one actual foot in the field.

Which internal heat gain source is typically the largest contributor in a residential cooling load?

Answer: Occupants and lighting combined

Occupants (sensible and latent body heat) and lighting are typically the dominant internal heat gain sources in residences.

What is 'infiltration' in the context of a residential load calculation?

Answer: Uncontrolled air leakage into or out of the building

Infiltration refers to uncontrolled air leakage through cracks, gaps, and openings in the building envelope.

When reading a duct layout on blueprints, what does a rectangular box with an 'X' drawn through it typically represent?

Answer: An exhaust or return air grille

A rectangular symbol with an X through it commonly denotes a return air grille or exhaust register on HVAC plans.

In load calculations, what does 'sensible heat' refer to?

Answer: Heat that changes air temperature without changing moisture content

Sensible heat causes a measurable temperature change in the air without altering its moisture (humidity) content.

Which window orientation typically produces the highest solar heat gain in a US residential cooling load?

Answer: West-facing windows during afternoon hours

West-facing windows receive intense direct afternoon sun, producing the peak solar heat gain during the hottest part of the day.