HELPFUL AIR CONDITIONING INFORMATION

Conversions and General info:

1 watt = 3.4 BTUH

1 HP = 746 watts = 2,545 BTUH

12,000 BTUH = 1 ton of refrigeration

400 CFM per ton nominal

Volts X Amps = watts (single phase)

Volts X Amps X 1.73 = watts (three phase)

Watts X 3.4 = BTUH

Chilled water coils usually require between 2 and 3 GPM per ton for cooling.

Make-up air = 1.08 x CFM x Delta T

Ventilation / Indoor Air Quality = 1.08 x CFM x Delta T, 20 CFM per person OSA

Determining Cooling Loads:

This information is for sensible (dry) cooling only.

Wet processes or Humidity requirements need special consideration not included in this information!

Calculations:

Number of lights – (96 watts for 3 bulb fixture)

Number of HEPA filters - (1065 BTUH for 115 volt Mac 10 filter)

Envelope load – wall and roof construction and materials, window size and type, unconditioned adjacent spaces, etc.

Process equipment – List from Customer with voltages and amp draws is best.
Not Nameplate info. This number will be too high and the air conditioning will be oversized. (Use a multiplier of .5 to .65, if nameplate is only number available.)

PC’s = approx. 350 watts each.

Workstations = approx. 500 watts each.

Exhaust requirements – Quantify amount of exhaust. Air to make-up for exhaust will usually increase heat load significantly.

Diversity factor – How much of the time is process equipment running?

People – 250 BTUH sensible, 230 BTUH latent. (at rest or light duty)

Approximately 80% of the capacity of packaged air conditioning equipment is available for sensible cooling. (Not 100%)