HVAC Load Calculations Flashcards
6 cards from real HVAC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 HVAC Load Calculations flashcards as text
Which industry standard manual is most widely used in the US for residential HVAC load calculations?
Answer: Manual J
ACCA Manual J (Residential Load Calculation) is the ANSI-approved industry standard used to determine heating and cooling loads for homes.
What does 'sensible heat' refer to in HVAC load calculations?
Answer: Heat that causes a change in temperature without a change in state
Sensible heat causes a measurable temperature change and is calculated using the formula Q = 1.1 × CFM × ΔT for air systems.
In a Manual J calculation, what is the term for the maximum heat gain a building experiences, which determines the required cooling capacity?
Answer: Peak cooling load
The peak cooling load (design cooling load) represents the maximum rate of heat gain at the design outdoor conditions and governs the selection of cooling equipment.
Which factor accounts for heat transfer through walls, roofs, windows, and floors in a load calculation?
Answer: Conduction (envelope) load
The conduction (envelope) load calculates heat flow through the building envelope using the formula Q = U × A × ΔT, where U is the assembly's thermal transmittance.
What is the design temperature difference (ΔT) based on in a Manual J load calculation?
Answer: Outdoor design temperatures from ACCA or ASHRAE data minus indoor setpoint
Manual J uses ACCA/ASHRAE outdoor design temperatures (typically the 99% heating or 1% cooling condition) minus the indoor design setpoint to calculate ΔT.
Latent heat load in HVAC calculations is primarily associated with:
Answer: Moisture removal (dehumidification) from the conditioned space
Latent load accounts for the energy required to condense and remove moisture from the air, calculated using Q = 0.68 × CFM × ΔGrains.