24 National Oilheat Research Alliance
typical residential applications. The impact
of the copper on fuel quality can be
tremendously reduced when a one-pipe
fuel line configuration is used.
Steel pipe can offer advantages particularly
when an overhead installation is
necessary or there is potential for damage
copper piping. However, if steel pipe is
in contact with concrete or soil, protection
from corrosion is needed. When steel
pipe is used, connections should be made
with malleable iron fittings. Cast iron
fittings can easily be broken and therefore
should NOT be used on fuel lines.
Flexible fuel lines are available and are
sometimes used to connect the fuel lines
to the burner on appliances that have
“swing-out” combustion chamber access
doors. These lines allow for maintenance
to be performed without disconnecting
the fuel lines from the burner.
Sizing
Fuel lines should be sized and installed
in accordance with the manufacturers’
instructions for the fuel unit being used.
Lines should be large enough so that
excess vacuum is not created and small
enough that all air can be completely
bled from the system.
For normal residential use, a minimum
of 1/4" iron pipe or 3/8" OD copper line
is recommended. However, ½" OD
copper significantly lessens vacuum and
is not overly large as to impede evacuating
the air. In areas that experience frigid
temperatures, ½" OD tubing should be
considered with outside tanks.
The fuel line to the house is insulated, but the piping could benefit
from some rustproofing paint.
Two views of suction lines with shutoff valve at the burner.
As shown here, fuel lines should be reasonably protected from
damage and secured.
All fuel lines that contact concrete or soil should be protected in
a continuous run of corrosion resistant tubing.