One Pipe vs. Two Pipe
With a one-pipe system the fuel pump only
brings as much fuel from the tank as it pumps
through the nozzle. If there’s a one-gallon (1.00
GPH) nozzle installed, and the pump pressure
is 100 PSI, then fuel will flow through
the line at a rate of one gallon per hour. With
a one-pipe system, if a customer burns 1,000
gallons of fuel per year, then 1,000 gallons pass
through the filter and strainer.
With a two-pipe system the fuel pump brings
as much fuel from the tank as its gear set is
designed for. The fuel unit pumps some of that
fuel through the nozzle and sends the rest back
to the tank through the return line. Since a
typical pump can move about 17 gallons per
hour, this means that for that same customer
who burns 1,000 gallons a year, 17,000 gallons
pass through the fuel filter and strainer!
26 National Oilheat Research Alliance
NORA recommends one-pipe installations
whenever possible. It’s easy to see that a one
pipe system sends far less fuel through filter
and strainer on the way to the burner to get
the same job done.
One Pipe System
Many systems currently operating two-pipe
can operate just as well, if not better, when
converted to a one-pipe system. One-pipe
installations offer several advantages over twopipe
systems, including:
• elimination of the potential liability
of leaking return lines. Unlike suction
line leaks, which cause burner troubles,
return line leaks often go unnoticed.
In many situations a return line leak
can continue for extended periods of
time and is only discovered when there
appears to have been a dramatic increase
in consumption