HOTSY 771/772 • 8.941-246.0 • Rev. 12/10
11
PRESSURE WASHER
OPERATOR’S MANUAL
10. Enlarge the diameter of each nozzle using a #55
drill bit (.052"). Make sure the holes are drilled
straight and all metal shavings are cleared from
inside nozzles. Carefully reinstall the nozzles into
the burner ring, do not over tighten, do not use pipe
thread sealing compound.
11. Remove regulator cap screw, pressure regulator
adjustment screw and spring. (Refer to
Figure 7.)
12. Install the replacement spring, supplied in the Natu-
ral Gas Conversion Kit. (Refer to
Figure 7.)
13. Install the new plastic pressure regulator adjustment
screw. Assure that the screw top is flush with the
regulator top.
14. Replace the natural gas pilot. Inspect compression
fittings on aluminum gas line. If fittings are dam-
aged, replace with compression fitting supplied with
orifice kit. To replace compression fittings cut the
aluminum gas line as close to the old compression
fitting
as possible. Install new compression fitting. Install
aluminum gas line into pilot and tighten.
15. Install the burner ring assembly into the chassis and
secure.
16. Connect your natural gas supply to the inlet port of
the machine gas plumbing. (Refer to Figure 5.)
IMPORTANT: This gas line must be provided with a
shut off valve.
17. Install the gas pressure gauge or manometer into the
gas valve inlet pressure tap. This reading will indicate
the incoming gas pressure from your gas supply.
18. It is very important that the incoming gas pressure
be between 4.5 - 14.0 water column inches (.16
- .50 PSI). If adjustment is necessary, it must be
done by a qualified gas service technician.
WARNING: Maximum inlet pressure to machine 14.0
INSTALLATION INSTRUCTIONS
water column inches (.50 PSI).
19. Next install the gas gauge or manometer in the outlet
pressure tap port of the gas valve. (Refer to
Figure
5.) This reading will indicate the gas pressure going
to the burner ring.
20. Because of the safety features within the gas valve,
adjustment of the burner ring gas pressure can
only be made while the machine is running and the
burner is lit. Follow the instructions under
Before
Starting and To Start for details to operate burner.
21. Turn pressure regulator adjustment screw clockwise
to increase gas pressure. Adjust gas pressure to 3.5
water column inches. (.13 PSI).
22. Turn off the burner and pump. Shut off gas supply
to the machine before removing the gas gauges or
manometers. Always check new gas line connec-
tions with soapy water for leaks.
23. Install the new cap screw. (Refer to
Figure 7.)
24. Remove LP gas label on gas valve.
25. Reinstall the chassis front and rear panels on the
machine.
Converting from Natural Gas
to LP Vapor Gas
CAUTION: Have a qualified gas service technician
install and service your equipment.
To convert back to LP vapor fuel, it is important to follow
the following instructions.
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
• 44 gas nozzles #66 orifice Part Number 908260
• LP Vapor gas pilot Part Number 829858
• LP Vapor gas conversion kit Part Number 753138
• LP Vapor fuel tank. We recommend using a mini-
mum 30 - 40 lb bottle. Bottle must have a shut-off
valve.
• LP gas hose - four feet long minimum, 3/4" inside
diameter. Must have 3/4" male NPT thread end
to attach to machine. Available through Hotsy,
Part Number 707432. This hose is supplied in the
771 portable gear/LP bottle Rack Kit, Part Number
280771.
• Gas primary regulator. Controls the pressure from
the gas bottle into the gas valve. Regulator must
be capable of handling 376,000 BTU/Hr. with an ad-
justment range of 12.0 to 14.0 inches Water Column.
Figure 7 - Pressure Regulator
PARTS
CAPSCREW
PRESSURE REGULATOR
ADJUSTING SCREW
SPRING
BLACK
BLACK
RED
SILVER
BLACK
STAINLESS
STEEL
COLOR CODE FOR
LP GAS NATURAL GAS
Pressure Regulator Housing
