Above Average Propane Usage - Not Necessarily a Leak

Propane companies hear this more often from residential consumers during periods of cold weather. It is more common for propane marketers in the southern states to get these calls than northern marketers just because the weather and climate is so much warmer in the south. During abnormally cold weather this is very common but it doesn't always men there's a gas leak. If you smell propane, get out of your house and call your propane company immediately.

Home Heating in Cold Weather

If you heat your home with propane and it's cold outside, you are going to use more propane. The same goes for heating with natural gas or electricity. The United States encompasses such a large geographic area that the climate regions of the country range from frigid to tropical. These contrasting environments signify a large difference in heating seasons as well as varying lengths of the heating seasons. Some parts of the southern U.S. have almost no heating season at all while parts of the northern U.S. seem to have a heating season for the bulk of the year.

Consumers in the warmer regions of the U.S. may think they have a leak after an unseasonable winter or extended period of cold weather more often than propane consumers in cold climates. The reason being that people in these warmer climates are not used to cold winters and they can't see how they could have used so much gas. The example here actually occurred in San Antonio, Texas after an extended period of cold temperatures in January of 2007.

San Antonio is known for hot summers and mild winters and the propane customer was unable to believe that he had gone through so much gas in just a few weeks. The customer has a 1,000 gallon propane tank that supplies the following LP Gas appliances (with appliance BTU ratings):

  • 3 Water Heaters - 40,000 BTU/hr each
  • 2 Central Furnaces - 200,000 BTU/hr each
  • 1 Clothes Dryer - 35,000 BTU/hr
  • 1 Gas Range - 65,000 BTU/hr
  • 2 Fireplaces (with ceramic logs) - 26,000 BTU/hr each
  • 1 Pool Heater - 425,000 BTU/hr

One gallon of propane has 91,547 BTU's. Appliance BTU ratings indicate the appliance usage at 100% capacity. In other words, a furnace with a 200,000 BTU/hr rating means the furnace will use 200,000 BTU's per hour when it is running at "full blast". The furnace will use about 2.2 gallons of propane in one hour's time (200,000 ÷ 91,547 = 2.18). The total load on this house is 1,097,000 BTU/hr meaning that if all appliances are running at 100%, the total use will be about 12 gallons of propane an hour (1,097,000 ÷ 91,547 = 11.98). At this propane usage rate, a total of 288 gallons are being used each day.

Realistic Propane Usage

We all know that nobody will run all of their appliances at 100% all day long so let's take a reasonable approach to higher than average gas usage using the example above during off peak usage (Summer months) versus peak usage (Winter months).

Summer Propane Usage - During off peak months, propane will be used by cooking appliances, water heaters, clothes dryers and the maybe pool heaters. If the gas range, dryer and water heaters are used at a rate of 25% capacity 2 hours per day, the gas usage will be about 1.2 gallons per day.
220,000 BTU/hr ÷ 91,547 = 2.4 gal/hr • 2.4 gallons x .25 = .6 gallons • .6 gallons x 2 hours = 1.2 gallons of propane

Using the same calculation above, the usage rates will differ as capacity and length of use change.
25% capacity for 2 hours - 1.2 gallons per day
25% capacity for 6 hours - 3.6 gallons per day
50% capacity for 2 hours - 2.4 gallons per day
50% capacity for 6 hours - 7.2 gallons per day

If the pool heater (425,000BTU/hr) is used for one hour per day at 75% capacity, add 3.5 gallons per day to the numbers above (425,000BTU/hr ÷ 91,547 = 4.64 gal/hr • 4.64 x .75 = 3.48 gallons). As you can see, pool heaters use a lot of gas and playing with these numbers, you can get an idea of normal off peak propane usage rates.

Winter Propane Usage - The winter months bring more usage of all energy sources for heating so the usage numbers above will drastically change as heating requirements increase. For instance, let's take an unseasonably cold week with the same appliances above and compute the propane gas usage with the same hours of use adding the use of the furnaces for heating. If the furnaces are used at 50% capacity for 12 hours, the daily gas usage will increase by about 26 gallons. Note that does not include the two fire places.
400,000 BTU/hr ÷ 91,547 = 4.4 gal/hr • 4.4 gallons x .5 = 2.2 gallons • 2.2 gallons x 12 hours = 26.4 gallons

Using the same calculation above, the usage rates (during heating) will differ as capacity and length of use change.
50% capacity for 18 hours - 39.6 gallons/day or 277.2 gallons/week
75% capacity for 06 hours - 19.8 gallons/day or 138.6 gallons/week
75% capacity for 12 hours - 39.6 gallons/day or 277.2 gallons/week
25% capacity for 12 hours - 13.2 gallons/day or 92.4 gallons/week
25% capacity for 18 hours - 19.8 gallons/day or 138.6 gallons/week
25% capacity for 24 hours - 26.4 gallons/day or 184.8 gallons/week

Pool Heater Gas Usage - If you add the propane consumption of a pool heater, the numbers really start to climb. Pool heaters are high capacity appliances that can consume more than 4.5 gallons of propane per hour (425,000 BTU/hr ÷ 91,547 = 4.64 gal/hr). If it takes 4 hours to heat the pool on a cool day, the pool heater may use 18.5 gallons. We bring pool heaters up because they are such high demand appliances that can really cause consumers to think they have a gas leak...when in reality, they just need to be mindful of not leaving the pool heater on for an extended period of time. The pool heater in the above example will consume 100 gallons of propane in less than a day if left running at capacity. If you're heating your pool, keep an eye on the gas gauge.

Propane Usage Comparison

As described and explained here, the propane usage rates during peak and off-peak seasons contrast sharply and can leave some people guessing where all their gas went after a cold weather period. While many people believe they must have a leak, their system is actually leak-free and they just used the gas. This is particularly true in warm climate regions where an extended period of cold weather prompts a sharp increase in propane usage through home heating. People get used to the gas bill being the same month after month and then when an uncommonly cold norther sets in, they use more propane than they thought they ever would. The fact is they just aren't used to it and it doesn't necessarily mean there's a leak within the system.

Also See Checking For Propane Leaks