Desa B350D Service Manual

Also see for B350D: Owner's manual Owner's manual Owner's manual

Contents

H I G H P R E S S U R E P O R T A B L E F O R C E D A I R H E A T E R S E R V I C E M A N U A L8COMPONENT OPERATIONAll Systems Working TogetherThere are four basic systems within theheater: the fuel system, the air system, theignition system, and the flame control sys-tem.The Fuel System: The fuel pump pulls fuelfrom the fuel tank and pressurizes it. The fuelpump pushes fuel through a filter and asolenoid valve and out the burner headnozzle. A fine mist of fuel is sprayed into thecombustion chamber.The Air System: The motor turns the fan.The fan pushes air into and around the4S E C T I O NFUEL SYSTEMFuel PumpThe fuel pump is a single stage gear-typepump designed for two-pipe usage. The term“two-pipe usage” means that provisions mustbe made to return excess fuel from the pumpback to supply tank. Figure 1 shows positionof pump on heater.The fuel pump is directly connected to motorshaft. When motor on heater runs, the fuelpump starts working. The fuel pump drawsfuel into one of the ports marked “INLETS.”After fuel pump draws fuel into INLET port,the fuel is then pressurized in the pump. Thefuel pump then forces fuel to the burner headnozzle thru the port marked NOZZLE.The port marked “PRESS ADJ” contains anadjustment screw. Turning this screw willincrease or decrease the fuel pump pres-sure. Check fuel pump pressure by attachinghigh pressure gauge into the port marked“GAGE.”As mentioned above, the port marked “RE-TURN” is used to return excess fuel back tosupply tank.Be careful when working on fuel pump. Fuelpump operates under high pressure.Figure 1 - Fuel PumpPUMPMODEL PRESSURE350,000 BTU/Hr. 100 psi600,000 BTU/Hr. 110 psicombustion chamber. The air that goes intothe combustion chamber mixes with the fuelfor combustion. The air is heated and pro-vides a stream of clean, hot air.The Ignition System: The transformer sendsvoltage to the spark plug. The spark plugignites the fuel and air mixture.The Flame Control System: This systemcauses the heater to shut down if the flamegoes out. It also allows the fan to continuerunning after normal shutdown of heater.This cools the combustion chamber.