Specifications

Part number 550-142-120/0113
WM97+ gas-fired water boiler — Boiler Manual
– 116 –
Inspect refractory and replace burner gasket
1. See Figure 121, page 117 part D.
a. Inspect the refractory to make sure it is intact, with no
visible damage.
b. If the refractory must be replaced, use a wide-blade putty
knife to gently pry the refractory from the heat exchanger
cover plate. The refractory is attached with silicone ad-
hesive and should separate with a little pressure on the
putty knife.
DO NOT gouge or crack the refractory. The re-
fractory is made of ceramic fiber materials. Read
the ceramic fiber WARNING on page 96 before
handling or disposing of ceramic fiber materials.
c. When replacing the refractory, apply a ring of silicone
adhesive on the cover plate. Place the refractory onto
the cover plate. Before handling the assembly, allow the
adhesive to set enough that the refractory is firmly held
in place.
2. Remove the burner gasket (item 12) from the heat exchanger
cover plate.
3. Clean the gasket surface with a soft brush to remove any
gasket residue.
4. The burner gasket must be replaced with a new one when the
boiler is re-assembled after servicing.
Inspect and clean the heat exchanger
1. Access the heat exchanger interior by following the previous
instructions. Remove and inspect the heat exchanger cover
plate gasket. Replace if necessary.
2. See Figure 121, page 117 part E.
3. Use a strong light to visually inspect the interior of the heat
exchanger. Make sure the flueways (tubes) are clear and
unobstructed.
4. Use a vacuum cleaner to remove any accumulation on the
heating surfaces. This includes removing any pieces of refrac-
tory than may have dropped into the exchanger.
DO NOT use any solvent when cleaning the ex-
changer.
5. If the vacuum cleaner is unable to clean completely, wash the
heating surfaces with clean, warm water.
a. Place a bucket under the boiler condensate drain con-
nection.
b. Then loosen the condensate trap upper nut and slide the
trap off of the drain connection. (See Figure 71, page 62
for reference.)
c. Spray water into the heat exchanger and tubes to remove
sediment. Collect water in the bucket below.
6. Inspect the heat exchanger cover plate gasket. Replace if is
damaged in any way.
Reinstall components
1. See Figure 121, page 117 for reference.
2. First, re-install the heat exchanger cover plate/refractory/
blower/venturi/gas valve assembly on the heat exchanger.
a. Seat the heat exchanger cover plate gasket on the heat
exchanger sealing surface.
b. Secure the heat exchanger cover plate (item 6) to the
heat exchanger with the five 6-mm nuts using a 10-mm
wrench.
c. Tighten the nuts gradually, adjusting a little at a time.
Alternate and repeat until all are tightened evenly.
d. Do not over-tighten (torques no more than 45 inch-
pounds).
3. Reinstall the burner (item 11), burner gasket (item 12) and
burner access cover seal (item 13) on the heat exchanger
cover plate (item 6).
a. Insert and tighten the burner cover plate screws and wash-
ers (item 10) using a Phillips screwdriver. The screws must
be secure, with torque no more than 20 inch-pounds.
4. Reinstall the igniter assembly (item 7).
a. The igniter gasket must be intact and in good condition.
Replace with a new gasket if necessary.
b. Insert the igniter into the cover plate opening, with the
gasket in position.
c. Reinstall the two Phillips head screws finger tight.
d. Use a torque wrench to tighten the igniter screws. DO
NOT exceed 25 inch-pounds torque.
e. Reconnect the igniter wire and the igniter ground wire.
5. Reconnect the flexible gas line to the gas valve using two
wrenches.
6. Reinstall the air inlet silencer (item 1) by pressing onto the
venturi (item 5). Rotate the air silencer clip (item 8) and snap
it onto the gas line.
7. Reconnect the wire harnesses to the blower and gas valve.
8. Reinstall the condensate trap on the boiler condensate drain
connection. (See Figure 71, page 62 for reference.)
Perform a complete start-up procedure when put-
ting the boiler back into service. See page 87 and all
instructions for start-up and verification. Include a
soap suds leak test on all interior and exterior gas
piping after starting the boiler.
Cleaning heat exchanger flue side, 155 (continued)
Figure 120 Legend for Figure 121, page 117
A Boiler interior
B Burner assembly
C Boiler interior, showing
heat exchanger cover plate
(item 6) and burner cover plate
seal (item 13), with burner
assembly removed
D Exchanger cover plate, blower
and other components,
showing combustion chamber
refractory (item 16)
E Heat exchanger interior
F Boiler lower interior, showing
condensate dish (item 20)
1 Inlet air silencer
2 Blower assembly
3 Gas valve
4 Burner access cover
5 Venturi assembly
6 Heat exchanger cover plate
7 Igniter assembly
8 Air silencer clip
9 (5) Heat exchanger cover plate
retainer nuts,
10 Burner cover retainer screws,
M4 Phillips plus flat washers
11 Burner
12 Burner gasket
13 Burner access cover seal
14 Burner gasket sealing surface
15 Burner sealing surface (lower
surface of burner flange)
16 Combustion chamber
refractory
17 Heat exchanger tube sheet
18 Heat exchanger cover plate
gasket
19 Heat exchanger outer shell
20 Condensate dish
21 Condensate dish joint
22 Control housing, rotated
forward