6
FUEL UNITS/FUEL LINES
Fuel supply "level with" or "above" burner:
A single stage fuel unit connected to the fuel sup-
ply with a single supply line is the most common type of installation for these conditions. Manual
venting of the fuel unit is usually required on initial start-up. Failure to vent air could result in an
air lock/oil starvation condition. (One pipe)
Fuel supply below the level of burner:
Use a single stage fuel unit in lift conditions of up to 10
ft., and a two stage fuel unit when the lift exceeds 10 ft. Both conditions require the use of a
return line which purges the fuel unit of air returning it to the fuel tank. The "by-pass" plug must
be inserted into the fuel unit when installing a return line. (Two pipe)
Fuel line installation:
Continuous lengths of heavy wall copper tubing are recommended and
should be installed under the floor when possible. Always use flare fittings. Always install fittings
in accessible locations. Never use teflon tape on any fuel fitting. Use of teflon will void any war-
ranty. Fuel lines should not run against the appliance or the ceiling joists.
Fuel line valve and filter:
Install two high quality shutoff valves in accessible locations on the
oil supply line. Locate one close to the tank and the other close to the burner ahead of the filter.
Some filters come with built-in shutoff valves. Install a generous capacity filter inside the building
between the fuel tank shutoff valve and the burner locating both the filter and the valve close to
the burner for ease of servicing.
CAUTION:
All oil feed lines to burners must be air tight. Use only flare fittings when assembling
oil lines since the slightest air leak, caused by loose fittings, bad gaskets or any other reason,
can cause a foaming oil stream which will cause any of the following conditions:
a) Intermittent firing, causing safety shutdown
b) Poor starts
c) Smokey starts
d) Continual sooting of boiler and burner parts including the cad cell
e) Reduced firing rate, inefficient operation and erratic fire pattern
f) A dangerous combustion condition, allowing the firebox to fill with a lean mixture (too
much air in the oil stream) which could cause a delay in ignition of the fuel mixture until
the danger point has been reached.
Suction Vacuum Test.
A fuel pump suction vacuum test should be performed. See the fuel
pump manufacturers literature for details. The suction vacuum must be limited to ensure that
there is adequate pump lift. This problem becomes proportionately larger with underground
tanks. If the following procedures are followed, burner related problems will be minimized:
a) Connect vacuum gauge to oil pump. Suction vacuum must not exceed 10 inches of mercury
for single stage pumps and 15 inches for two stage pumps. It is preferable to stay below
these limitations.
b) When the suction line is tight and properly installed the pump will hold its vacuum for a
minimum of 60 minutes after shutdown.
c) Installation of a check valve in the suction line of a two pipe system is advisable under all
circumstances. Be sure the check valve fittings are airtight.
