16
Maintenance
Fuel Control System
These machines utilize a fuel solenoid valve located on
the fuel pump to control the flow of fuel to the combus-
tion chamber. This solenoid valve, which is normally
closed, is activated by a flow switch when water is
flowing through it. When an operator releases the
trigger on the spray gun, the flow of water through the
flow switch stops, turning off the current to the fuel
solenoid. The solenoid then closes, shutting off the
supply of fuel to the combustion chamber. Controlling
the flow of fuel in this way allows for an instantaneous
burn or no burn situation, thereby eliminating high and
low water temperatures, and combustion smoke
normally associated with machines incorporating a
spray gun.
CAUTION: Periodic inspection is recommended to
insure that the fuel solenoid valve functions
properly. This can be done by operating the
machine and checking to see that when the trigger
on the spray gun is in the off position, the burner is
not firing.
Fuel Pressure Adjustment
To adjust fuel pressure, First install a pressure gage
into the port just after the pump fuel exit. Turn the
adjusting screw (located at the regulator port)
clockwise to increase, and counterclockwise to
decrease. Do not exceed 200 psi or lower the pressure
below 130 PSI, when checked at the post-pump
pressure port.
The fuel pressure may need to be adjusted due to
altitude. For every 500 ft altitude above sea level, the
boiling point of water goes down 1 °F. At high altitude
environments, this boiling point change may require the
heat input to be lowered so the water input does not
turn to steam earlier than at the factory settings and
activate the pressure sensors and pressure relief
equipment when the unit is operated and much higher
altitudes from factory settings or local dealer site
settings. Check with your dealer before making local
site fuel pressure adjustments.
Also, as ambient temperature changes seasonally, the
fuel temperature in the feed tank and air temperature
inlet can impact fuel flow. In more extreme tempera-
tures, this local-site adjustment may also require
different fuel nozzles for fuel inlet temperatures that are
at seasonal extremes (higher or lower) in locations
where the temperature changes are beyond moderate
temperatures of between 40°F and 90°F. Colder
temperatures will make for a thicker flow and less fine a
fuel spray while hotter temperatures will make for a
thinner flow a more fine spray with the same nozzle.
Consider alternate nozzle configurations from the
baseline factory-supplied nozzle for operating in such
temperature extremes if performance is not meeting
needs with air band and fuel pressure settings alone.
NOTE: When changing fuel pump, a by-pass plug
must be installed in return line port or fuel pump will
not prime.
Gun Setting Instructions
For EHASR Only
SR-Series gage KNA Part
Number 8.717-379.0
Electrode Setting
Burner Nozzle
Keep the tip free of surface deposits by wiping it with a
clean, solvent-saturated cloth, being careful not to plug
or enlarge the nozzle. For maximum efficiency, replace
the nozzle each season.
Initial Air Adjustments:
Allow sufficient air to obtain a
clean burning flame by loosening the lock screws and
moving the air shutter and if necessary the bulk air
band.
Reduce the air supply until the flame tips appear
slightly smoky, then increase the air just enough to
cause the flame tips to appear absolutely clean.
Burner Air Adjustment
The oil burner on this machine is preset for operation at
altitudes below 500 feet. If operated at higher altitudes,
it may be necessary to adjust the air band for a #1 or #2
smoke spot on the Bacharach scale.
To adjust, start machine and turn burner ON. Loosen
two locking screws found on the air band and close air
band until black smoke appears from burner exhaust
vent. Note air band position. Next, slowly open the air
band until white smoke just starts to appear. Turn air
band halfway back to the previously noted position.
Tighten locking screws.
Landa MHP Operator’s Manual 8.913-925.0 - T
