Hi,

This is the second winter in my "new" house -- furnace is approx 15
years old. Runs on oil -- tank is outside in very cold climate, so oil
is mixed with kerosene by fuel company. The furnace has an issue in
that, as the oil volume in the tank decreases, air seems to sneak into
the line. Last year this occurred reliably at 1/4 tank (according to
the plastic gauge); this year it has begun to happen with as much as
1/3 tank remaining.

Generally, when I discover that the furnace has stopped running, I can
bleed the line for approx. 10 seconds, see the pink oil sputter out
air, turn to a richer black color, and close the line. The furnace
kicks in and will often run for awhile again (possibly days, if
necessary) until at some point air gets into the line again. I sense
that as oil volume continues to decrease, the need to bleed becomes
more frequent. The problem disappears when the next oil delivery fills
up the tank.

This is a one line system. My furnace 'guy' says that a two line
system will fix the problem, but he (working alone, and somewhat
older) is uncomfortable doing the work in the extreme cold of winter
(line runs through a low crawlspace; oil tank and furnace on opposite
sides of house).

My questions are (a) is he right? (his price for installing a second
line was quite reasonable) and (b) is there *anything* I can do this
season to help? Waiting until the furnace stops (often in the middle
of the night) to wake up to a cold house is inconvenient to say the
least.

thanks!
Aaron