DeWalt DXH135HD Instruction Manual page 6

ADJUSTING PUMP PRESSURE
Due to varying fuel viscosities and normal component wear the pump pressure
on this heater may need to be adjusted. The heater should only be operated at
the manufacturer's recommended burner setting.
ADJUSTmENT PROCEDURE:
1. Fill fuel tank.
2. Start heater.
3. Locate the fuel pressure adjustment screw (ref. #29) in the exploded parts
drawing. The pressure adjustment screw is located at the rear of the
heater, in the air filter housing cover (approx.2" from the left side and 1"
from the top). Remove and discard the rubber cap (ref. #4) to expose the
screw.
4. Using a flat bladed screw driver, turn the pump pressure adjustment
screw clockwise to increase pump pressure and/or counter-clockwise
to decrease pump pressure. Base pump pressures can be found in the
specifications chart on page 3 of the "Operating Instructions and Owners'
manual".
5. For best results, the nose cone in the combustion chamber should be
cherry red with no dark spots and the flame should not extend beyond the
nose cone.
ImPROPER PRESSURE ADJUSTmENT
Problem: Heater does not have a strong consistent flame.
Heater smokes and spits raw fuel.
Nose cone does not get cherry red.
Adjustment: Pump pressure is too low.
Turn adjustment screw clockwise to increase pump pressure.
Problem: Flame extends beyond the end of the heater.
Adjustment: Pump pressure is too high.
Turn adjustment screw counter clockwise to decrease pump
pressure.
Daily Maintenance Schedule
1. GENERAL. Make general visual inspection of heater for loose or damaged
parts. Check nuts and bolts to insure against looseness caused by vibration
or rough handling. Damaged parts should be repaired or replaced before
using heater again. Check heater operation to be sure it is operating
normally (See "Servicing" section for description of normal operation).
2. FILTERS. Dirty air or fuel filters will cause an imbalance in the air-fuel
mixture. The best indication that this condition exists is an increase in
odors or difficulty getting your heater to ignite. This heater should never be
operated without the filters in place. If required, clean filters as described
under "500 Hours" and "Annual Schedules".
500 Hour Maintenance Schedule
1. AIR INTAKE FILTER. Remove and wash the filter element with a mild
detergent, dry thoroughly and replace. Do not oil the filter element. If your
heater is used where there is considerable dust or dirt, clean as often as
necessary (approximately every 50 hrs.).
2. REMOVE DUST. Clean heater twice a season (more often under dusty
conditions). Remove accumulated dust from the transformer, burner, motor
and fan blades with compressed air. Wipe area clean with a clean dry cloth.
Inspect area to insure all foreign materials are removed, especially around
the burner and combustion area.
3. CAD CELL. Clean the glass portion of the cad cell with a soft dry cloth.
4. NOZZLE. Accumulation of dirt from fuel and carbon from the compressor
vanes will eventually fill up the passages in the nozzle, resulting in reduction
of fuel and air flow. Pressure will gradually increase giving improper fuel-air
mixture and excess odor and smoke. If this occurs, replace the fuel nozzle.
5. FUEL TANK. Clean twice a season (during frequently used periods, clean
twice a month). Drain and flush the fuel tank with clean fuel oil.
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