HVAC Load Calculation and System Design

Question 1

What does Manual J refer to in residential HVAC design?

Accepted Answer

The ACCA standard for residential heating and cooling load calculations

Answer

Manual J (published by ACCA) is the industry-standard method for calculating residential heating and cooling loads to properly size HVAC equipment.

Question 2

What unit is used to measure the cooling capacity of HVAC equipment in the US?

Accepted Answer

BTU/hr or tons

Answer

Cooling capacity in the US is rated in BTU/hr or tons (1 ton = 12,000 BTU/hr), describing how much heat the system can remove per hour.

Question 3

What are 'design conditions' used for in HVAC load calculations?

Accepted Answer

The outdoor temperature and humidity values used to size equipment for the worst-case weather scenario

Answer

Design conditions are the outdoor temperature and humidity values (typically the 99% heating and 1% cooling design temperatures for a location) used to calculate peak heating and cooling loads.

Question 4

What is the 'U-factor' of a building assembly?

Accepted Answer

The overall heat transfer coefficient (inverse of total R-value) of a building assembly

Answer

The U-factor is the overall heat transfer coefficient of a building assembly (wall, window, roof), calculated as 1 divided by the total R-value; lower U-factors indicate better insulation.

Question 5

What is 'infiltration' in the context of building load calculations?

Accepted Answer

Uncontrolled air leakage into and out of a building through gaps and cracks

Answer

Infiltration is uncontrolled air leakage through envelope gaps (around windows, doors, penetrations), which adds to heating and cooling loads depending on season.

HVAC - Heating, Ventilation, and Air Conditioning Practice Test

HVAC - Heating, Ventilation, and Air Conditioning Practice Test

HVAC Load Calculation and System Design