HVAC Formulas | PDF | Conversions

HVAC FORMULA’S AND CONVERSIONS PDF FILE

HVAC FORMULAS::

TON OF REFRIGERATION – The amount of heat required to melt

a ton (2000 lbs.) of ice at 32°F

288,000 BTU/24 hr.

12,000 BTU/hr.

APPROXIMATELY 2 inches in Hg. (mercury) = 1 psi

WORK = Force (energy exerted) X Distance

Example: A 150 lb. man climbs a flight of stairs 100 ft.

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high

Work = 150 lb. X 100 ft.

Work = 15,000 ft.-lb.

ONE HORSEPOWER = 33,000 ft.-lb. of work in 1 minute

ONE HORSEPOWER = 746 Watts

CONVERTING KW to BTU:

1 KW = 3413 BTU’s

Example: A 20 KW heater (20 KW X 3413 BTU/KW = 68,260 BTU’s

CONVERTING BTU to KW:

3413 BTU’s = 1 KW

Example: A 100,000 BTU/hr. oil or gas furnace

(100,000 ÷ 3413 = 29.3 KW)

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COULOMB = 6.24 X 1018 (1 Coulomb = 1 Amp)

E = voltage (emf)

I = Amperage (current)

R = Resistance (load)

WATTS (POWER) = volts x amps or P = E x I

P(in KW) = E x I

1,000

U FACTOR = reciprocal of R factor

Example:

1 R = .05U

= BTU’s transferred / 1 Sq.Ft. / 1ºF / 1 Hour