You may have seen the slot on the ‘Underground Storage Tank Permit‘ found on PortlandMaps.com which says “Integral Burner” but you might not have any idea what that mean.
Well today you can find out! This permit can show where a oil tank was installed. Aside from HOTs (Heating Oil Tanks) which are USTs & ASTs (underground and aboveground storage tanks) there is the category Integral. As type of stand alone furnace these integral burners usually have a small tank around 5 gallons. These integral oil burning furnaces are often built into the home itself, they are integrated into the home usually by being under a big grate in the living room of smaller homes.
These furnaces are not typically found in addition to USTs but there is no way to be sure without an oil tank search.