HOTSY 771/772 • 8.941-246.0 • Rev. 12/10
OPERATOR’S MANUAL
PRESSURE WASHER
10
INSTALLATION INSTRUCTIONS
4. Use pipe thread sealing compound at all hose connec-
tions and at gauge port pipe plugs to prevent leaks.
DO NOT use teflon plumbing tape.
5. Attach a 3/4" inside minimum diameter LP gas hose
to the inlet port of the machine. Make sure you use
a hose that is suitable for LP gas.
6. Install the gas pressure gauge or manometer into
the gas valve inlet pressure tap. The reading at this
location will indicate the incoming gas pressure from
your gas bottle primary regulator.
It is very important that the incoming gas pressure
be between 12.0-14.0 water column inches (.43 - .50
PSI).
WARNING: Maximum inlet pressure to machine 14.0
water column inches (.50 PSI).
To control the pressure from the LP bottle you must have
a primary regulator. If you purchase a regulator from
Hotsy, Part Number 860178, it will be preset from the
manufacturer and should not require adjustment. If your
primary regulator does not produce the correct pressure
range contact your local Hotsy Service Representative.
After connecting the gas hose to your regulator, install
the regulator on the bottle. The regulator 860178 has
a POL fitting which will screw directly into an LP Vapor
fuel bottle.
7. The gas pressure coming out of the gas valve and
going to the burner ring has been factory set and
should not require adjustment. If you replace your
gas valve, you will need to adjust the new valve for a
burner ring gas pressure of 11 water column inches
(.39 PSI). Follow the installation and adjustment in-
structions provided with your replacement valve.
8. After correct pressures have been established,
remove gauge and replace with pipe plug.
9. Always check new gas line connections for leaks with
soapy water.
10. Reinstall the chassis front panel on the machine.
Converting From LP to Natural Gas Fuel
CAUTION: Have a qualified gas service technician
modify, install and service your equipment.
The Model 771 has been factory built to use LP Vapor fuel,
however this model can be field converted to run on natural
gas fuel. It is very important to follow these instructions
when converting the unit for natural gas fuel.
Modifications will need to be made to several components
within the washer. Before starting, disconnect gas and
electrical power supply from the machine.
You will need the following items:
• Gas pressure gauge or gas manometer
• 10" Adjustable wrench
• Medium Phillips head screwdriver
• Large slot head screwdriver
• 3/16" Allen wrench
•
Pipe thread sealing compound for gas connections
• Drill and drill bit #55 (.052)
• Natural gas orifice, Part Number 753141
• LP To Natural Gas Regulator Valve Conversion Kit
Part Number 753142
1. Remove both the chassis front and rear panels from
the machine to gain access to the burner assembly.
2. Turn the gas valve ON/OFF knob to the OFF position.
Refer to
Figure 5.
3. Disconnect the wire leads to the gas valve.
4. Remove the burner ring assembly from the machine by
removing the U-bolt and the two nuts. Save all hard-
ware for reassembly after modifications are made.
5. Disconnect the aluminum gas line from the pilot.
(Refer to Burner Assembly).
6. Carefully remove the LP gas pilot from the burner ring
(Refer to
Figure 6).
7. Remove the LP gas orifice from the pilot (Refer to
Figure 6).
8. Install natural gas orifice, Part Number 753141.
9. Carefully remove burner nozzles from burner ring.
Figure 5 - Gas Valve
Outlet Pressure Tap
To Burner Ring
Pilot Outlet
Pilot Adjustment
(Under Cap Screw)
ON/OFF Knob
Inlet Pressure Tap
Pressure Regulator
Adjustment
(Under Cap Screw)
Gas Valve
✽
Gauge
Connect Gas
Here
✽
Not Supplied w/Machine
Figure 6 - LP Gas Pilot
Burner Ring
Gas
Pilot
Gas Orfice &
Alumninum Gas Line
Wire Lead To
Gas Regulator
Valve
