Poor burner perfomance....

Fizz

My neihbor has single-pipe system(steam) which works fine except when his oil supply gets low,then it is reduced burner out-put. His oil tech told him he needs new burner as the "eye" of burner gets gooky, requiring cleaning. His boiler is 1990's WM, with no other issues in system.

Steamhead

Tell him to switch oil techs. This is an oil supply problem, not a burner problem.

If the oil line comes out of the top of the tank, it might not go down low enough inside the tank to work properly as the oil level drops.

If the oil line comes out of the bottom, there may be something partially blocking it. So when the tank gets low, there is not enough gravity-induced pressure to move the oil.

A good oil tech should be able to fix this.

New England SteamWorks

Another good guess is the tank is an old one. Believe it or not, algae like to grow low in oil tanks between the water and the oil. This turns into sludge. Which clogs everything. Best and cheapest remedy: Stop waiting to order 100 gallons of oil when the tank is empty. Instead, order oil when the tank is half full and fill it.

newagedawn

blow back the oil line and bleed all the crudd out of the line, youll be fine after that, and add some sludge clean to the tank

Fizz

Great advice! Thanks to all.