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20 • On-Demand Water Heater Service Handbook for 240, 340 & 540 Condensing Models
5. There may be a computer board
(PCB) and/or gas valve fault. Refer
to error codes 510 and 551.
Code 721: False Flame
Detection
A false flame was detected by the
system during start up. No flames
should have been present, so the
system stopped the ignition process.
1.
WARNING! Shut off all gas and
power to the unit. Failure to do
so could lead to fire, explosion,
personal injury or death.
2. Inspect the flame sensor to
see if it is dirty. Also, check the
ceramic housing for cracks. Clean
the assembly, if necessary. See
“Cleaning the Rod Assembly (Flame
Sensor and Air/ Fuel Ratio Rod)” on
3. Contact the technical service
department for further assistance.
Code 741: Remote Control
Problem
Error Code: 741
This code indicates a
miscommunication between the
temperature remote controller and
the water heater. This code is
not
associated with the built-in controller
for indoor models.
NOTICE:
•
If you disconnect the remote
from the heater with the power
supply on, this error code will
result. Turn off power before
disconnecting the remote from
the heater.
•
Remote controllers for outdoor
models will vary in the field.
Outdoor models manufactured
prior to April 2015 were
equipped with remote controller
TM-RE40/100112572; current
outdoor models are equipped
with TM-RE42/100209924.
1. Verify that the remote is compatible
with the water heater. Refer to the
remote’s instruction sheet and the
heater’s installation manual.
2. Verify that only a single remote
is installed. With indoor models,
only one remote may be used in
addition to the built-in temperature
controller. An incorrect remote or
multiple remotes will result in this
error code.
3. Make sure that all wiring is
connected to the remote controller
properly.
4. Power surges can cause this fault. If
frequent power surges occur, install
adequate surge protection to prevent
nuisance faults.
5. Check the voltage across the wires
coming to the remote. Normal
voltage should be 10-25 VDC. If
within normal range, replace the
remote, part 100209924. If the
voltage is out of range, replace the
computer board (PCB).
Code 751: Temperature
Controller Problem
This code indicates a
miscommunication between the water
heater and the
built-in
temperature
controller (indoor models only).
NOTE:
This code is
not
associated with
the remote controller.
1. Check that all wiring is properly
connected to the built-in
temperature controller.
2. Power surges can cause this fault. If
frequent power surges occur, install
adequate surge protection to prevent
nuisance faults.
3. Check the voltage across the
wires that are connected to the
remote. Normal voltage should
be 11 VDC and 25 VDC. If within
normal range, replace the built-
in temperature controller. If the
voltage is out of range, replace the
computer board (PCB).
Code 761: Communication
Error in Easy-Link or Multi-Link
System
A 761 error code means that the
parent unit (Easy-Link system) or
multi-unit controller (Multi-Link
system) has lost communication with
at least one heater.
This code will display on the parent
heater in an Easy-Link system
or
on
the multi-unit controller of a Multi-
Link system.
To address this error, do the following:
1. Inspect the wiring between the
Parent heater/Multi-Unit Controller
and the heater identified by the
code.
2. Verify that the heater in question
has power to the computer board.
•
Make sure the switch above the
computer board is on.
•
Make sure that a fuse or surge
absorber in the fuse box has not
blown.
•
Verify proper supply power to
the water heater in question.
If the error appeared while
troubleshooting the water heater, do
the following:
•
Easy-Link System:
Cycle the power of the parent
unit off, then back on again.
