Troubleshooting
Guide
29|
Page
REPLACING
THE
HEAT
EXCHANGER
There
are
many
possible
causes
of
a
heat
exchanger
failure:
•
Contaminated
air
with
a
high
level
of
dust,
lint,
sand,
grease,
aerosols
or
other
contaminants,
can
become
airborne
and
enter
the
air
intake.
The
contaminants
build
up
within
the
fan
and
burner
assembly
causing
abnormal
flame
conditions
due
to
lack
of
combustion
air,
damaging
many
components
of
the
unit.
•
Scale
can
build
up
from
very
hard
water.
Lime
scale
will
form
on
the
inside
of
the
heat
exchanger
tubes
readily
at
high
temperatures.
This
scale
prohibits
heat
from
reaching
the
water
which
causes
excessive
heat
within
the
heat
exchanger
copper,
and
it
will
eventually
burn
and
leak.
Along
with
changing
the
heat
exchanger,
it
is
important
to
identify
the
CAUSE
of
the
need
for
replacement,
and
fix
the
problem
so
it
does
not
occur
again
1)
TOOLS
‐
Gather
the
following
materials
together:
a.
Degreaser
in
a
pump
action
bottle
b.
Sheet
of
100
Grit
Sandpaper
c.
#2
Philips
Screw
Driver
d.
Needle
‐
Nosed
Pliers
e.
Duct
Tape
f.
Flashlight
g.
Air
Compressor
h.
Old
Towels,
at
Least
Three
2)
PREPARE
THE
UNIT
a.
POWER
‐
Disconnect
power
to
your
unit.
b.
GAS
‐
Shut
off
the
gas
supply
to
the
unit.
c.
WATER
–
Drain
the
unit.
Refer
to
p.
21
for
instructions.
3)
REMOVE
MANIFOLD/GAS
ASSEMBLY,
BURNER
a.
Follow
steps
1
‐
7
of
the
previous
section,
“Cleaning
the
Combustion
Components”.
This
will
tell
you
how
to
remove
the
PCB,
manifold/gas
assembly,
and
burner
4)
WIRES
‐
There
are
several
wire
clips
that
need
to
be
removed
to
free
the
heat
exchanger
a.
Locate
the
brown
wire
clip
connected
to
the
GFI,
and
disconnect
it.
b.
On
the
bottom
left,
disconnect
the
ceramic
heating
elements
(white
wires).
c.
Locate
the
white
bypass
valve
clip
on
the
left
‐
hand
side
of
the
combustion
chamber
with
red/black
wires.
Disconnect
it.
d.
Upwards
toward
the
left
side,
remove
a
blue
connection
to
the
over
‐
heat
cutoff
fuse
e.
Remove
the
two
spade
connections
on
the
high
limit
switch.
f.
Disconnect
the
igniter
plug
(purple
wires
and
blue
plug)
at
the
bottom
right.
g.
Along
the
bottom,
disconnect
the
plug
into
the
proportional
valve
(red
&
white
wires).
