FORMULA FOR NATURAL GAS COSTS TO HEAT A POOL TO 80 DEGREES YEAR ROUND
Pool Length x Width x 8* Therm x .62** cents = Cost Per Year
*Requires 8 therm per square feet of surface area to heat to 80 degrees.
** .62 cents is average cost for Southern California.

Example: 75 x 45 x 8 x .62 = $16,740.00

HOW TO REDUCE NATURAL GAS COSTS
Have Pool Maintenance Company perform preventative maintenance on heaters, check heat exchanger tubes for calcification or corrosion. If necessary de-lime and de-soot heat exchangers. 2. Verify proper heater size for pool (BTU rating).

FACTORS AFFECTING HEAT LOSS

1. Temperature difference between air and water
2. Pool surface area - evaporation (depth is not a factor)
3. Humidity
4. Winds around pool area - windbreaks such as landscaping or fencing can reduce
5. Geographic location

ENERGY LOSS (AS REPORTED BY THE U.S. DEPARTMENT OF ENERGY)
Outdoor Pools
70% Evaporation
20% Radiation
10% Ground

HOW LONG WILL IT TAKE TO HEAT THE POOL?
For Commercial Pool Heaters:

EXAMPLE

• Determine the number of BTUs (British Thermal Units) needed to raise 165,000 gallons of pool water from 50 degrees F to 85 degrees F.
• Use the formula 1 BTU will raise 1 pound of water 1 degree F in 1 hour
• Multiply the volume in gallons by 8.33 (weight of 1 gallon of water) to determine the weight of the water that must be heated.
• Multiply the water weight by the desired temperature rise to detemine the number of BTUs needed.
• Divide the BTUs needed by the available heater output in BTUs to find the number of hours it will take to heat the water.
• Example:
  Water Volume: 165,000 gallons
  Temperature Rise: 35 degrees F
  Water Weight: 165,000 gallons x 8.33 = 1,374,450 lbs.
  1,374,450 lbs. X 35 degrees F = 48,105,750 BTUs needed to heat
  Heater output: 1,890,000 BTUs
  48,105,750 BTUs needed to heat to desired temperature divided by 1,890,000 BTUs output = 25 hours

  TURNOVER TIMES
  Turnover time is the number of times in a 24 hour period that the total gallons of water must circulate through the filtration system.

  Swimming Pools 6 hours
  Wading Pools 1 hour
  Spas 30 minutes

  BATHER LOAD
  California State Codes restrict the number of bathers to:
  1 bather for each 20 square feet of water surface area (for pools)
  1 bather for each 10 square feet of water surface area (for spas)

  Example:

  75' (length of pool) x 50' (width of pool) = 3750 square feet
  3750/20 = 187.5 bathers

  CALCULATING POOL VOLUME
  Selecting pool equipment and water treatment chemicals depends upon a working knowledge of your pool's capacity in gallons. To find a pool's approximate volume, first calculate its area, which corresponds to the length times the width, then multiply the area by the average depth and a conversion factor (7.48). The trick is finding the "length and width" of a pool with an irregular shape. If you can't find a shape below that approximates your pool, divide the outline into units of simpler shapes, figure the volume of each chunk, and then add them together for the total.