Raypak AVIA 264A Installation And Operation Manual page 42

1. Follow the heat exchanger removal process as
shown in "Heat Exchanger Removal" section.
2. The heat exchanger has a baffle on the sides, or the
bottom, depending on the model size, which has to
be removed.
3. Remove the heat exchanger from the unit and wash
with a garden hose, making sure soot is removed
from the spaces between the fins.
4. Reverse the heat exchanger removal procedure to
reinstall.
NOTE: In extreme cases it may be necessary to do
steam cleaning at the local car wash. DO NOT WIRE
BRUSH.
Heat Exchanger Reinstall
It is highly recommended to replace the top combustion
chamber with the refractory during the heat exchanger
reinstallation process. Failing to do so can result in
damage to the heater and potential dangerous operating
conditions. See Figure 70.
Figure 70. Top Combustion Chamber
Unitherm Governor (U.G.) Replacement
1. Shut off water, gas and electricity, close valves and
relieve pressure.
2. Drain heat exchanger.
3. Remove retainer plug located next to the outlet pipe
connection.
4. Unsnap old U.G. to remove from retainer plug. Snap
in new U.G.
5. Reinstall retainer plug, taking care to lubricate
gasket with a non-petroleum based grease such as
AquaLube.
42
UG PLUG O-RING
UNITHERM
GOVERNOR
GASKET
Figure 71. Unitherm Governor
To test the operation of the Unitherm Governor, place in
hot water over 120°F (49°C), and watch for movement
against spring. If there is no movement, replace the UG.
A WARNING: When removing the burners or heat
exchangers, take precautions to avoid creating airborne
dust and avoid inhaling airborne fibers. When cleaning
spills, use wet sweeping or High Efficiency Particulate
Air (HEPA) filtered vacuum to minimize airborne dust.
Use feasible engineering controls such as local exhaust
ventilation or dust collecting systems to minimize
airborne dust. Wear appropriate personal protective
equipment including gloves, safety glasses with side
shields, and appropriate NIOSH-certified respiratory
protection, to avoid inhalation of airborne dust and
airborne fiber particles.
UG PLUG