Homeowners who use propane as a primary heating source may have propane storage tanks with capacities ranging from 120 to 1,000 gallons. The largest residential propane tanks are typically installed in the coldest climates because of longer winters and higher heating demands. Determining how much propane a specific furnace will use requires calculations based on the size of the furnace. A furnace may use less than a 1/2-gallon of propane an hour or more than 2 gallons an hour, depending on size.
British Thermal Units
The heating capacity of furnaces is measured in British Thermal Units (BTUs). The higher the BTUs, the more powerful the furnace -- and the more propane it consumes. Someone living in central Florida may have a relatively low-power furnace rated at 45,000 BTUs an hour while someone in Minnesota may have a furnace rated at 200,000 BTUs an hour. One gallon of propane will provide 91,547 BTUs with the furnace at its highest temperature settings, according to Propane 101, an online consumer information resource. This means that someone with a 45,000-BTU furnace would use roughly a 1/2-gallon of propane an hour while someone with a 200,000-BTU furnace would use about 2 gallons an hour at the furnace’s highest settings
Propane usage in a furnace is not an exact science. People who set lower temperature settings will use less propane than those who choose the highest settings. Temperature settings are influenced by weather, the efficiency of the furnace, insulation in the home and personal preferences. It is possible for two neighbors to have similar furnaces but use significantly different amounts of propane because of their usage patterns.
Homeowners concerned about propane usage in their furnace must also consider the impact of propane-powered appliances in the house. Clothes dryers, water heaters, gas ranges and pool heaters can also use propane as a fuel source. One propane dealer in 2011 reported about a family in San Antonio, Texas that used 12 gallons of propane a day -- and only 4.4 gallons for two furnaces. The remaining gallons were consumed in the family’s very large home by three water heaters, a clothes dryer, two fireplaces and a heated pool.
Before purchasing a furnace, ask the dealer to arrange for you to speak with other customers in your area who have the same furnace. Ask them about their propane consumption during winter months. Also talk with propane delivery companies about overall propane usage in the area.
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