A division of
Sullivan Heating & Cooling of Bremerton buys Master Hydronics
5373 Auto Center Way #205  Bremerton, WA 98312-6300    Phone: 360-405-0723

## Comparing operating costs of Electricity & various fuels.

The Future is Now.
1. Call your local utilities and fuel suppliers to get current rates. Ask about seasonal rates and the costs based on volume (this may influence how large of a fuel tank you may want to buy and the time of year you may want to purchase fuel).
2. The Annual Fuel Utilization Efficiency (AFUE) of a hot water boiler is the percentage of heat that actually gets used to provide useful heat (the remainder of the heat is lost to venting and standby losses.) The manufacturer of the appliance should provide the AFUE. For practical purposes, electric appliances are 100%, atmospheric natural gas boilers range from 83% to 85%, atmospheric propane boilers are near 80% to 83%, and oil fired boilers range from 86% to 87.7%.
3. For ease of comparison, convert electricity and fuel units of measure to a common unit of measure. Since most fuel appliances are rated in British Thermal Units per Hour (BTUH), electricity-heating units of Kilowatts per Hour (KWH) should be converted to BTUHs. To obtain figures near a dollar per unit figure, BTUHs should be converted to therms.

CONVERSIONS, MEASURES, AND HEATING VALUES:
• 1 Therm = 100,000 BTUs
• 1 KWH = 3412 BTUH = 0.03412 Therms
• 100 Cubic Feet (CCF) of Natural Gas = 1.069 Therms
• Gallon of Propane = 91,800 Btu – 0.918 Therms
• Gallon of #2 Fuel Oil = 139,000 Btu = 1.39 Therms

EXAMPLES:
• Cost per therm of electricity
• = (cost per Kwh) (Kwh / therm conversion) (1 / AFUE)
• = (.055 per Kwh) (Kwh / 0.03412 therms) (1 / 1)
• = (.055) / (0.03412) (1)
• = \$1.61 per therm of electricity
• Cost per therm of propane
• = (cost per gallon) (heating value of propane) (1 / AFUE)
• = (\$1.00 per gallon) (gallon per 0.918 therms) (1 / 0.80)
• = (\$1.00) / (0.918) (0.80)
• = \$1.36 per therm of propane
• Cost per therm of oil
• = (cost per gallon) (heating value of oil) (1 / AFUE)
• = (\$1.00 per gallon) (gallon per 1.39 therms) (1 / 0.87)
• = (\$1.00) / (1.39) (0.87)
• = \$0.83 per therm of oil
• Cost per therm of natural gas
• = (cost per CCF) (CCF per 1.069 therms) (1 / AFUE)
• = (\$0.56 per CCF) (CCF per 1.069 therms) (1 / 0.84)
• = (\$0.56) / (1.069) (.084)
• = \$0.62 per therm of natural gas

### Please consult with your local utilities or fuel suppliers to obtain current pricing and heating values.

Last Updated 03/18/2007