Oil Furnace
Re: 2-Pipe Installation
An oil furnace can be installed with either a single oil line or with two oil lines connected to the fuel-oil pump.
► On an installation where the oil can flow from the tank to the pump by gravity (the tank must be located higher than the pump), a one-pipe system can be used, i.e. a suction line and no return line.
► On an installation where the tank is below the level of the pump the oil must be lifted. Most commonly used for this application is the two-pipe system, i.e. both a suction and a return line.
Fuel oil pumps will typically have multiple inlet ports and one or more return/bypass ports.
IMPORTANT! When converting to a 2-pipe installation, it is necessary to install a bypass "allen" screw inside the pump, under the return/bypass plug.