"Now, look at the right side of the chart," Elena said. "Those curved lines rising up are your Relative Humidity (RH) lines. What percentage is your dot sitting under?"
Marcus stood in the lobby. The thermometer still read 72°F, but the air felt crisp. The heaviness was gone. Mr. Henderson walked by, no longer mopping his brow, and gave them a thumbs up. how to use a psychrometric chart
Marcus carefully followed the diagonal line labeled 65°F until it crashed into the vertical line of 75°F. "Right here?" "Now, look at the right side of the chart," Elena said
Marcus traced a horizontal line from his dot to the right axis. "It reads... 0.012?" The thermometer still read 72°F, but the air felt crisp
"It feels like a swamp in here!" Mr. Henderson shouted, mopping his brow with a handkerchief. "The thermostat says 72 degrees, but I’m dripping with sweat!"
"Sharp eye," Elena smiled. "That curved line is the 'Rain Line,' or 100% saturation. If you just cool the air to 55°F on that path, you hit the curve at about 60°F. That means condensation forms. Water drips. The coil freezes. We have a problem."
She handed Marcus a digital psychrometer. "First, take a reading."