If you have this appliance, and the pilot light is lit, you are still using energy even if the appliance is not turned on. Please check the check box and it will automatically calculate the monthly and yearly cost for you. Pilot lights typically burn 24 hours every day and it consumed about four to 12 therms/month. In our calculation, we assumed that the average BTUs/hr is 1100 or 8 therms/month.
The cost to operate a furnace is dependent on a number of factors such as square footage of your home, temperature, efficiency of your furnace, etc. A furnace also cycles on and off during the day and it would be very difficult for you to estimate the number of hours it is in use. Natural gas furnaces and boilers have been required to have pilotless ignitions since 1980, so this section only applies to older furnaces and space heater.
If you would like an estimate of the natural gas costs associated with your furnace, please see the table on the switching from electric to natural gas page.