Using the nominal 400 CFM per ton, how much airflow does a 3-ton air conditioner need?
Answer in CFM.
Show the answer
1200 CFM
Airflow = tons x 400 CFM per ton = 3 x 400 = 1,200 CFM.
Reference: Nominal airflow per ton of cooling
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Airflow psychrometrics practice questions
30 questions from the hvac fundamentals practice test.
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Airflow psychrometrics practice test
10 questions, graded as you go, with the reason for every answer. No sign-up.
What this covers
- Airflow
- Capacity
- Sensible heat
- Total heat
- Sensible heat ratio
- Static pressure
- Duct airflow
- Latent heat
- Psychrometrics
- Heat transfer
- Filters
- Duct basics
- Fault diagnosis
Sample questions
An air handler moves 1,200 CFM and the air temperature changes by 20°F across the coil. Using Q = 1.08 x CFM x ΔT, what is the sensible heat transfer?
Answer in Btu/h.
Show the answer
25920 Btu/h
Q = 1.08 x CFM x ΔT = 1.08 x 1,200 x 20 = 25,920 Btu/h.
Reference: Sensible heat formula Q = 1.08 x CFM x ΔT
A 10 kW electric heater (34,120 Btu/h) raises the air temperature by 25°F. Using Q = 1.08 x CFM x ΔT, what is the airflow, to the nearest CFM?
Answer in CFM.
Show the answer
1264 CFM
CFM = Q / (1.08 x ΔT) = 34,120 / (1.08 x 25) = 34,120 / 27 = 1,264 CFM.
Reference: Sensible heat formula; temperature-rise airflow method