Homeowner Emilio Zamora safely exited his home in the 500 block of Yellowstone Court after a smoke detector went off around 5:30 a.m., Battalion Chief Michael Ahlin said.
Smoke was coming from the second floor of the single-family, wood frame house when firefighters arrived, Ahlin said. Zamora said no one else was inside the home.
The fire was confined to the heating system on the first floor and was extinguished by 6 a.m. There were no injuries.
Nineteen firefighters from Petaluma, Rancho Adobe Fire Protection District, Cal Fire and the Wilmar Volunteer Fire Department responded to the blaze.
The fire caused $2,000 in damage to the home's contents and $8,000 to the structure, Ahlin said.