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NORA Oilheat Technicians Manual

Chapter 4 Fuel Units and Oil Valves 4-20 Fuel Units and Oil Valves the two leads of the switch together. As this field fix removes the delay feature of the valve, a new coil should be installed at the earliest possible time. The delayed oil valve is needed on burners with older pumps. Most of the new burners utilize non-delay instant opening solenoid valves because of the relative unreliability of the thermal delay switch. Figure 4-24 shows a solenoid valve. Manufacturers have gone to microprocessor based primary controls with Valve- Delay-On and Motor-Delay-Off, commonly known as pre- and post purge technology. The delay is built into the primary so the delay timing can be more precisely controlled. It is becoming increasingly popular for manufacturers to attach the solenoid valve, controlled by the primary, directly to the fuel unit. See Figure 4-25. Anti-siphon valve and oil safety valve If the oil tank is higher than the burner, some codes require an overhead suction line and an automatic valve that will break the siphon should an oil line leak develop. Two popular anti-siphon valves are the Webster Oil Safety Valve (OSV), and the Suntec PRV. Figure 4-26 shows a Suntec PRV. Its job is to protect against line leaks and tank A conventional fuel line flared fitting is installed in the outlet port of the delayed valve (in most cases this will be the same fitting you have removed from the nozzle discharge port) and the fuel line to the drawer assembly fuel pipe should be reinstalled. With some small amount of reworking, it should be possible to use the same fuel line that was on the burner before installation of the delayed valve. Servicing: The most sensitive part of the delayed valve system is the thermal delay switch that is taped to the valve coil. Should the valve at any time fail to operate due to a defective time delay switch, it is possible to temporarily remove this switch from the circuit by removing the tape bindings and twisting Figure 4-26: Suntec PRV Figure: 4-24: Drawing of a solenoid valve Figure: 4-25: Fuel pump with solenoid


NORA Oilheat Technicians Manual
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