Page 68

NORA Oilheat Technicians Manual

Chapter 4 Fuel Units and Oil Valves 1/2 In. O.D. Tubing—Inlet Line Figure 4-13: Booster fuel unit; pressurized system installation Max. Intake Pressure at Burner 10 PSI 0-30 PSI Pressure Gauge # 1 # 2 # 3 4-10 Fuel Units and Oil Valves Tank Manifold Air Bleed— Highest Point in Line 1/2 In. O.D. Tubing— Manifold Line Solenoid Valves 35 Ft. Max. Auxiliary Filter Suspended Furnaces 1/2 In. O.D. Tubing— Return Line Approx. 3 Inches H 15 Ft. Max. Fuel unit limitations 1. NFPA31, the National oilburner code, limits the shaft seal pressure to 3 PSI, although most pumps can take up to 10 PSI. 2. Single-stage pumps should not be operated beyond 6" of vacuum when hooked up one pipe. Single stage, two pipe installations should not be operated above 10" of vacuum. 3. Two-stage pumps should generally operate below 12" of vacuum because at very high vacuums, oil foams within the pump. Pumps with integral solenoid valves There are two types of pumps with built in electronic shut off valves called integral solenoid valves. One is the blocking valve pump and the other is the by-pass valve pump. The blocking valve stops the flow of oil to the nozzle just like an externally mounted solenoid valve does. With this pump, the oil is shut off two ways: with the electric valve, and the pressure regulating valve. The by-pass valve pump has a valve that controls the flow of oil to the nozzle indirectly by diverting oil flow inside the pump. When it is time to shut off the oil flow the dumping valve opens, causing the pressure to drop quickly and the pressure regulating valve to close sooner. This is opposite the blocking valve operation. When the blocking valve opens, oil flows; when the dumping valve opens, oil stops. Either type of valve will give you quick cutoff, but to get delayed cut-in, and cleaner starts, you need either a valve-on delay primary control, a hydro-mechanical pump delay, or an electric delay device. Servicing and testing the fuel unit Primary venting and bleeding In a one pipe system, when a pump runs out of oil or picks up air due to high vacuum or a leak or break in the oil supply line, the air must be bled from the fuel unit and line after the tank is filled or the supply line is repaired. Failure to do this properly can cause pulsation, changes in flame condition, or excessive dripping at the nozzle after the burner shuts off. There are two methods for air elimination in a one pipe system. If the system is a gravity feed and R Pipe Cap Suntec Boost Pump & Motorset Filter Shut Off Valve


NORA Oilheat Technicians Manual
To see the actual publication please follow the link above