CSLB C-20 HVAC ContractorPlanning and LayoutMedium
A Manual J load report shows a total cooling load of 30,000 Btu/hr with a calculated Sensible Heat Ratio (SHR) of 0.80. What is the latent cooling load?
- A6,000 Btu/hr
- B9,000 Btu/hr
- C24,000 Btu/hr
- D3,600 Btu/hr
Show answer & explanationAnswer & explanation
Correct answer: A. 6,000 Btu/hr
Sensible load = Total × SHR = 30,000 × 0.80 = 24,000 Btu/hr. Latent load = Total − Sensible = 30,000 − 24,000 = 6,000 Btu/hr.
Why the other options are wrong
- B. Incorrect result from a miscalculated percentage.
- C. This is the sensible load, not the latent load.
- D. Incorrect math; not derived from the correct SHR relationship.
Latent Load Calculation
Latent load represents moisture removal capacity and is found by subtracting the sensible load (Total × SHR) from the total cooling load.
- Sensible = Total × SHR
- Latent = Total − Sensible
- High SHR means most load is sensible (dry heat)
Memory trick: SHR tells you the dry share; what's left is the wet share.