Troubleshooting
Guide
31|
Page
CHECKING
THE
FLOW
SENSOR
If
the
tankless
unit
is
properly
connected
to
water,
gas,
and
power
supplies
but
the
fan
motor
does
not
initiate
when
water
is
run
through
it,
the
flow
sensor
is
most
likely
not
working
properly
and
not
telling
the
PC
Board
to
initiate.
1)
TOOLS
‐
Gather
the
following
materials
together:
a.
Degreaser
in
a
pump
action
bottle
b.
#2
Philips
Screw
Driver
c.
Flashlight
d.
Old
Towels,
at
least
three
2)
PREPARE
THE
UNIT
–
a.
Drain
the
unit
by
following
the
procedures
on
p.
21.
b.
Disconnect
power
to
the
unit.
3)
FRONT
COVER
‐
Remove
the
front
cover.
4)
COMPUTER
BOARD
a.
Remove
the
screw
holding
the
computer
board
to
the
manifold,
and
let
the
computer
board
hang
in
front
of
the
unit
b.
Disconnect
the
flow
sensor
wire.
5)
DISCONNECT
FROM
WATERWAY
a.
The
flow
sensor
is
located
behind
the
computer
board.
b.
Remove
the
waterway
clips
on
each
side
of
the
flow
sensor
by
pushing
on
the
tabs.
6)
CHECKING
THE
FLOW
SENSOR
a.
Check
for
functionality.
Flow
rate
is
determined
by
an
impeller
that
spins
as
fluid
runs
through
it.
b.
Blow
into
the
inlet
of
the
flow
sensor.
Listen
for
the
spinning
impeller;
it
should
spin
freely
for
a
few
seconds.
If
it
comes
to
rest
abruptly
or
doesn’t
spin
at
all,
it
needs
to
be
cleaned
or
replaced.
c.
Place
the
flow
sensor
into
a
container
of
lemon
juice
or
another
degreaser
for
30
minutes
and
check
the
spinning
capability
again.
d.
Test
the
cleaned
flow
sensor
by
“jumping”
the
system:
i.
Reattach
the
flow
sensor
wires.
ii.
Turn
power
back
on
to
the
unit.
(GAS
SHOULD
STILL
BE
OFF)
iii.
Blow
into
the
flow
sensor;
if
the
fan
initiates,
the
flow
sensor
successfully
read
the
airflow
and
should
now
work
properly.
7)
REASSEMBLE
‐
Reassemble
the
unit
in
reverse
order.
Ensure
that
the
O
‐
rings
and
waterway
clips
are
all
in
place.
Figure
34
