Guide To Pool Heating

Page 33 of 51

Formulas

A. ONE THERM= 100,000 BTUS

B. C.0.P. [Coefficient of Performance]= OUTPUT BTUS ÷ INPUT BTUS [KW x 3412]
Example: PCS1 C.O.P. is 44 = 60,000 ÷ (.396kw x 3412). PCS2 C.O.P. range is 25-40.

C.O.P. IS A UNIT OF COMPARISON TO ELECTRIC HEATERS.
I.E. PCS1 PRODUCES 44+ BTUS FOR EACH BTU INPUT USED.

C. EFFICIENCY= C.O.P. x 100
Example: 44 x 100 = 4400% efficient compared to electric heaters.

D. INPUT REQUIRED= 100,000 BTUS ÷ EFFICIENCY
Example: 100000 ÷ .70 propane = 142,857 input btus required.

E. THERM INPUT COST= (Input required ÷ btus per gallon) x per gallon cost
Example: (142857 ÷ 92310) x .72 = $1.11 for propane therm input.

F. COST PER 60K BTU= Therm Input Cost x .6
Example: Propane therm cost of $1.11 x .6 = $.67 for 60,000 btus of propane heat.

G. ONE MILLION BTUS÷ 1000 BTUS PER CU FT = 1000 CU FT [cubic feet]
Used when Natural Gas costs are quoted in million btus.

H. ONE MILLION BTUS÷ 3412 BTUS PER KW = 293.08 KW
Used when Electric costs are quoted in million btus.

I. ONE MILLION BTUS÷ 92310 BTUS PER GALLON = 10.83 Gallons
Used when Propane costs are quoted in million btus.

J. ONE MILLION BTUS÷ 139600 BTUS PER GALLON = 7.16 Gallons
Used when No. 2 Fuel Oil costs are quoted in million btus.

K. ONE GALLON OF LIQUID PROPANE= 36.2 CU FT

L. ONE THERM OF NATURAL GAS= 100 CU FT

M. ELECTRIC COST÷ C.O.P. = HEAT PUMP OPERATING COST

N. ELECTRIC COST ÷ C.O.P. = PCS1 OPERATING COST

O. HEAT CONTENT OF VARIOUS FUELS

Electricity = 3,412 BTUS PER KILOWATT

Propane = 92,310 BTUS PER GALLON — (2550 BTUS PER CU FT)

Fuel Oil = 139,600 BTUS PER GALLON

Natural Gas = 1,000 BTUS PER CU FT — (950-1150 BTU RANGE)