The Burner or heater generates a hot flame (tens of millions of btu/hour - several hundred times the power output of a typical home central heating system) by burning propane stored as liquid in tanks in the basket. No regulators are used on the tanks; when the pilot opens the blast valve on the burner, liquid at the full tank pressure passes through the vaporizing coils and is burned as it emerges from many nozzles in the burner, ignited by a pilot light that remains lighted during the entire flight. Since the tank pressure depends on temperature, for flights on very cold mornings such as this the tanks are kept warming overnight to make sure the burners work properly. The burner is not in operation all the time, but typically for several seconds each minute (depending on the outside temperature, balloon size, weight of passengers, etc.).