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1. Look into the burner opening in the heat exchanger cover
plate.
2. Use a trouble light and inspection mirror to inspect the heat
exchanger interior.
a. Make sure that there is no debris inside the heat ex-
changer.
b. Use the inspection mirror to check the condition of the
burner refractory that is adhered to the bottom of the
heat exchanger cover plate. It must be in good condition
with no indication of damage or sagging.
c. Make sure there are no signs of overheating or of ue
gas leakage.
If visual inspection of the heat exchanger indicates
the need, follow the procedures in the following to
remove the heat exchanger cover plate and fully
inspect and clean the interior. Obtain replacement
parts for any components that may be damaged or
that show signs of leakage.
1. See Figure109,page115 partA to locate components refer-
enced in the following.
2. Remove the air silencer and disconnect gas line:
a. See Figure109,page115 partA and partB.
b. Locate the clips connecting the air silencer (item1) to the
venturi (item5). Gently pull clips out and away from the
venturi. While holding clips out, slide silencer back and
o of the venturi. Set the air silencer aside.
c. Disconnect the exible gas line where it connects just
below the gas valve (item3).Lay the free end of the ex-
ible gas line to the side.
Usetwowrenches when disconnecting the
exible gas line to prevent damage to the gas
valve and other gas line components.
d. Disconnect wire harness connected to the gas valve and
two wire harnesses connected to the blower.
3. Remove the blower/venturi/gas valve assembly.
a. See Figure109,page115, partA.
b. Remove the two (2) 8mm locknuts connecting the blower
and cover plate.
c. Gently set blower/venturi/gas valve assembly aside. In-
spect blower/cover plate gasket. If gasket appears dam-
aged, discard and replace with a new gasket.
The burner, igniter and flame sense
rod must be removed and inspected
followingthe procedures beginning on
page111.
4. Remove the heat exchanger cover plate:
a. See Figure109,page115 partA, partB and partC.
b. Use a 10mm wrench or socket to remove the nuts
(item9) that secure the heat exchanger cover plate
(item6) to the heat exchanger. [Six (6) nuts (EVG220)
or seven (7) nuts (EVG299/300/399).]
c. Carefully li the cover plate assembly straight up vertically
until the cover plate refractory (partD, item16) clears
the heat exchanger studs.
d. Pull the assembly forward and out of the jacket.
e. Turn the cover plate assembly over and place on a at
surface.
1. See Figure109,page115 partB and C.
a. Use a wide-blade putty knife to gently pry the refractory
from the heat exchanger cover plate. e refractory is at-
tached with silicone adhesive and should separate with a
little pressure on the putty knife.
DO NOT gouge or crack the refractory. e re-
fractory is made of ceramic ber materials. Read
the ceramic ber WARNING on page94 before
handling or disposing of ceramic ber materials.
b. Carefully scrape o any adhesive residue with the putty
knife, avoiding scratching or gouging the heat exchanger
cover plate surface.
c. Wipe o any residue, clean o the work table surface and
turn the cover plate over, bottom side on the work surface.
2. Remove the burner gasket (item12) from the heat exchanger
cover plate.
3. Clean the gasket surface with a so brush to remove any
gasket residue.
4. Lay the heat exchanger cover plate aside for re-installation
later.
1. Remove and discard the heat exchanger cover plate gasket.
a. e Maintenance Kit includes a new gasket for use when
re-installing the cover plate.
b. Clean o any residue on the heat exchanger cover plate
gasket surface.
2. See Figure109,page115 partD.
3. Use a strong light to visually inspect the interior of the heat
exchanger. Make sure the ueways (tubes) are clear and
unobstructed.
4. Use a vacuum cleaner to remove any accumulation on the
heating surfaces. is includes removing any pieces of cover
plate insulation assembly than may have dropped into the
exchanger.
DO NOT use any solvent when cleaning the heat-
exchanger.
Part number 550-100-211/0122
– 112 –
(continued)
220 /29 9/3 00 /39 9
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