Specifications

Part number 550-142-120/0113
WM97+ gas-fired water boiler — Boiler Manual
– 112 –
Cleaning heat exchanger flue side, 70/110
Cleaning the WM97+70 or 110 heat
exchanger FLUE SIDE or accessing
the burner, if required
The boiler contains ceramic fiber materials. Use
care when handling these materials per instructions
on page 96 of this manual. Failure to comply could
result in severe personal injury.
Tools required
1. Long-handled Torx driver, #20.
2. Phillips head screwdriver, #2.
3. Torque wrench.
4. Putty knife.
5. Wrench or socket, 10 mm.
Before proceeding:
1. Shut down the boiler:
a. Follow “To Turn Off Gas to Appliance” instructions on
boiler and Lighting instructions. Close the boiler manual
gas valve.
2. Allow time for the boiler to cool to room temperature if it
has been firing.
3. Remove jacket front door by releasing the two clamps at the
bottom of the jacket door.
4. Lift the jacket door away from the boiler to remove.
Remove components to allow access
1. See Figure 119, page 113 part A to locate components refer-
enced in the following.
2. See Figure 119, page 113 part B.
a. Pull the silencer straight forward until it snaps free of the
blower housing. Set the air silencer aside. Rotate the air
inlet silencer if needed to clear as it is removed.
b. Remove the gas valve retainer clip (item 4) and set aside.
Pull the gas valve slightly to the right until it disengages
from the venturi (item 5).
Support the gas valve. DO NOT allow it to hang
from the gas valve flex line. Make sure the gas
valve-to-venturi O-ring (item 5, Figure 10, page 15)
remains on the gas valve sleeve.
c. Disconnect the blower end of the gas valve sense line
(item 8).
d. Remove the four 10-mm hex nuts (item 9)that secure the
heat exchanger cover plate (item 6).
e. Disconnect the ground wire and electrode wire from the
igniter (item 7).
f. Remove the blower retainer clip (item 15). Set aside.
g. Remove the blower by pulling down. Disconnect the two
blower wiring harnesses on the back side of the blower.
h. Lift the cover plate/venturi/burner assembly vertically
until the refractory (part 3, item 12) clears the heat ex-
changer.
i. Tilt the cover plate/venturi/burner assembly slightly
forward. Then pull the assembly forward and out of the
jacket.
j. Remove the igniter by removing the two Phillips head
igniter screws. Set the igniter, its gasket and screws aside.
Be careful when handling the igniter not to damage the
igniter ceramic.
k. Inspect the igniter ceramic and electrodes. Clean the
electrodes carefully with steel wool. If the igniter ceramic
is cracked or damaged, replace the igniter with a new one.
Handle the cover plate/venturi/burner assembly
carefully to avoid damage to the igniter or refrac-
tory. Place the assembly on a clean, flat surface
with the assembly on its side, as shown in Fig-
ure 119, page 113 part C and part D.
3. See Figure 119, page 113 part C.
a. Use a wide-blade putty knife (item 11) to gently pry
the refractory from the heat exchanger cover plate. The
refractory is attached with silicone adhesive 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.
Inspect and clean the burner
1. See Figure 119, page 113 part D.
a. Slide the refractory (item 12) over the burner and off.
Set the refractory aside where it will be kept clean and
protected from damage. If the refractory is damaged, it
must be discarded and replaced with a new one.
b. Remove the three #20 Torx screws (item 14) securing the
burner (item 10) to the cover plate. Set aside.
c. Remove the burner and its gasket (item 13).
d. Inspect the interior of the burner. Brush and vacuum the
interior if needed to remove lint or sediment. Alternative
cleaningmethods:•blowairornitrogenfromtheinside
out;•cleanwithawatersprayfrominsidetheburner;
Figure 118 Legend for Figure 119, page 113
A Boiler interior
B Boiler interior, with
components disconnected to
allow removal of combustion
chamber cover plate
C Combustion chamber cover
plate and components removed
from boiler
D Disassembling to access the
burner
E Heat exchanger interior
1 Inlet air silencer
2 Blower assembly
3 Gas valve
4 Gas valve retainer clip
5 Venturi assembly
6 Heat exchanger cover plate
7 Ignitor assembly
8 Gas valve sense line
9 (4) Combustion chamber cover
plate retainer nuts
10 Burner
11 Putty knife
12 Refractory
13 Burner gasket
14 (3) Burner retainer screws
15 Blower retainer clip