750-204
Profire D/LND
4-5
4.5 — Oil System
FIGURE 4-1. Gas Primary and Secondary Valve Arrangement: D 378-420
4.4.9 — Secondary Valve Adjustment: Dual Manifold
Each zone is controlled by a butterfly valve linked to a 14 point adjustment cam. The primary large butterfly
valve controls the main gas orifices and the secondary small butterfly valve controls the pre-mix gas spuds.
Refer to the adjustment section to setup the burner. In the low fire position, the secondary valve controlling the
pre-mix spuds is almost closed. After all adjustments are made throughout the modulating range, go back and
relight the burner. Upon startup, check that the fire is not burning behind the diffuser. If this happens, close the
secondary valve until this situation is corrected. Repeat several times.
4.5 — Oil System
4.5.1 — Oil Metering System
Fuel oil supply to the integral metering unit must be at 10 psi to 15 psi and up to 20 psi on separate metering
units. The oil spray should ignite as soon as the oil solenoid valve opens. If the oil spray fails to ignite, move the
metering unit adjustment lever a few degrees counterclockwise. This increases the amount of oil at low fire and
makes ignition easier, it will also increase the oil on high fire, so this must be checked later. Once adjusted, the
pump should operate with a minimum amount of adjustment. If a burner failure is caused by the oil metering
pump, check the following:
1. See that the oil tanks are not empty.
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