what is this on oil tank?

Not sure what this copper piping is for on top of the oil tank. It comes off the top and goes into the ground and then into the home. It has electricians tape on it at the connection. I found a disconnected line and a connected line at the furnace inside the home. Any ideas what this is? Thanks.

oil tank.jpg

Possibly to read the level of oil in the tank from inside the home?


Some oil furnaces have a supply and a return line. Mine had 2-3/8" lines that entered the top through a 2" bung cap that was compression sealed. The lines could be cut short of the bottom of the tank to stay out of the water that accumulates there from condensation. Your tank may have had the supply line come out of the bottom (poor plan) and the return go in the top. The line in your pic appears kinked for lack of sufficient radius.

Oil furnaces need yearly maintenance…not to mention the integrity of the oil storage tank. Did you check for rust on the bottom where the water inside settles to?

I thought it may be a return line until I found disconnected supply line at furnace and I traced the line in the crawl for a bit and it appears to be one of the two. I referred it out to HVAC tech for annual service etc as the furnace was 28 years old and was last serviced in 2006. There was some surface rust on the bottom of the tank as per the pic.


With any rust or bubbling paint on the tank I defer it and list it as showing indications that it may require repair or replacement anytime during the next five years. It is good that you deferred both the tank and the furnace.