The SUNTEC A2L oil pump has two nozzle outlets. It incorporates two blocking solenoid valves with in-line cut-off function, one for each nozzle outlet.
The gear set draws oil from the tank through the built-in filter and transfers it to the nozzle lines via the cut-off solenoid valves. A pressure regulating valve is used to bypass all oil which is not required at the nozzles.
In two-pipe operation, the by-pass plug must be fitted in the return port, which ensures that the oil bypassed by the regulating valve is returned to the tank and the suction line flow is equal to the gear set capacity.
In one-pipe operation (by-pass plug removed and return plugged), the oil which does not go through the nozzle lines is returned directly to the gear inlet and the suction line flow is equal to the sum of the 2 nozzle flows.
Bleeding in two-pipe operation is automatic : it is assured by a bleed flat on the piston.
In one-pipe operation, the plug of a pressure gauge port must be loosened until the air is evacuated from the system.
The solenoid valves of the A2L pump are of the “normally closed” type. Each solenoid valve is situated in one nozzle line. This design ensures extremely fast response and the switching can be selected according to the burner operating sequence and is independent of motor speed.
When the solenoids are non-activated, the valves are closed and all oil pressurized by the gear set passes through the regulator to suction or to the return line, depending upon pipe arrangement.
As soon as the solenoids are activated, oil passes to the nozzle lines at the pressure set by the pressure regulating valve.
The two solenoid valves can be operated independently.