Flow Sensor Cleaning Procedure

Flow Sensor Cleaning Procedure
Flow Sensor Cleaning Procedure
This instructional manual is only intended for use by a qualified service professional or authorized Noritz
Service Representative. Any unauthorized use of this manual may result in voiding the warranty.
Please contact Noritz Technical Support (866-766-7489) for additional support.
Noritz America Corporation
11160 Grace Avenue, Fountain Valley, CA 92708
Phone 866-766-7489 Fax 714-241-1196
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Flow Sensor Cleaning Procedure
1. Shut off water supply to heater and
remove cover
(1) Disconnect electrical power to
(2) Remove 4 screws
(3) Turn off gas and water
(4) Remove filter and drain unit
2. Locate Flow Sensor
(1) The flow sensor is a short black
elbow. It is typically found in the
lower part of the unit, directly
above the cold water connection.
(2) There are two flow sensors in the
following units: N-132, N-132M,
N-132M-ASME, N-1321M-ASME,
NC-380-SV; N-084, N-084M,
N-084M-DV, N-084M-ASME,
N-084M-DV-ASME, N-069M-DV.
3. Remove the flow sensor from the
(1) Remove the 2 “C” clamps that
hold the flow sensor in place
(2) Pull the pipe out of the front of
the flow sensor then pull the flow
sensor up and off of the bottom
of the heater. If water drains out,
dry it up to ensure that the wiring
connections are kept dry.
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4. Remove the flow sensor impeller
from the housing
(1) Locate the plastic dome inside
the short end of the flow sensor
(2) Put the long end of the flow
sensor in the palm of your hand
and hold the top with the tips of
your fingers on that hand. This is
to catch the retaining ring that
could fly out while performing
Step (3).
(3) Push down on the dome with a
screwdriver. It is typically
necessary to use the body of the
flow sensor as leverage while
doing this.
(4) A silver ring will come out along
with the flow sensor cylinder.
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5. Disassemble the flow sensor
(1) Set the metal retaining ring to the
(2) Remove the cross shaped cap
from the end of the flow sensor
with a needle nose pliers. When
removing the end cap, pull
straight out, don’t twist it off
(3) Dump out the internal
components of the flow sensor –
you should find a turbine and a
small cylinder with three notches.
(4) Remove the other end cap from
the large cylinder, this cap looks
like a “Peace” symbol
(5) Clean the flow sensor and big
cylinder – typically the types of
debris you would be looking for
would be Teflon tape, small
debris like dirt, plumber’s putty
or flux.
6. Reassemble the flow sensor
(1) Hold the “Peace” symbol end cap
between your thumb and index
(2) Drop the small cylinder with 3
notches onto the “Peace” symbol
end cap. The 3 notches should fit
over the “Peace” symbol.
(3) Locate the notches on the end of
the big cylinder. One side has 3
notches which will line up with
the “Peace” symbol end cap.
Push big cylinder and end cap
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(4) Insert the impeller into the
cylinder. Notice that the impeller
has a skinny/tapered end and a
broad end. The broad end will go
in first. You will be looking at the
tapered end when you drop into
big cylinder.
(5) Reconnect the cross patterned
cap on the end of the cylinder by
lining up the 2 notches.
(6) Put the cylinder back into the
flow sensor elbow. There is an
arrow on both the elbow and big
cylinder. Make sure they are in
the same direction.
(7) Drop in the metal retaining ring
and push it into place with a
screw driver to hold the flow
sensor in place
Skinny/Tapered End
Broad End
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7. Put the flow sensor back into the
(1) Push flow sensor down onto the
bottom connection then put “C”
clamp onto bottom. The larger,
rounded off “C” clamp is for the
(2) Push the pipe into the front of
the flow sensor then snap the “C”
clamp back into place. This “C”
clamp is squared off.
Bottom Clamp
Front Clamp
8. Pressurize the heater
(1) Replace the water filter on the
(2) Slowly return water pressure to
the heater. If any leaks are
found, shut the water back off
and repair the leak. More than
likely the “C” clamps are not
(3) Replace the front cover
(4) Turn on gas
(5) Reconnect electrical power
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