HVAC
Superheat vs Subcooling: What They Mean and Normal Ranges
Superheat and subcooling are the two readings technicians use to judge the refrigerant charge of an air conditioner…
HVAC
In-depth guides, formulas, and how-tos for engineering, trades, and everyday calculations. Learn the method, then use the matching free calculator.
HVAC
BTU per Square Foot: Chart by Room Size and Climate
The fastest way to size an air conditioner is to multiply the floor area by a BTU per…
HVAC
How to Find AC Tonnage from the Model Number
Every central air conditioner hides its size in the model number on the outdoor unit. Once you know…
HVAC
Air Change per Hour Requirements by Room Type (Table)
Different rooms need very different amounts of fresh air. A bedroom gets by on a fraction of one…
HVAC
How to Calculate Relative Humidity (RH Formula)
Relative humidity is the amount of water vapour in the air compared with the most it could hold…
HVAC
Duct Sizing Chart: How to Size Ductwork by CFM
A duct has to carry a set airflow without the air moving so fast that it whistles or…
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