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RTG2-42
Specifications
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Troubleshooting Manual
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Rheem RTG2-42, RTG53, RTG66, RTG74, SVC 810 Troubleshooting Manual

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Page 1
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
Tankless Gas Water Heaters Second Generation Indoor, Outdoor and Direct Vent Up to 199,000 BTU
Includes RTG2-42, RTG53, RTG66 and RTG74 models
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Table of Contents
Specifications common to all product lines ................................................................................ 4
Product (Model) History .............................................................................................................. 5
Sequence of Operations ................................................................................................................ 7
Sensors and Safety ........................................................................................................................ 8
Oxygen Depletion Sensing System Operation............................................................................ 8
How to Reset the Four (4) Hour ODS Timer.............................................................................. 9
Overheat Film Wrap ................................................................................................................... 9
Heat Exchanger Thermistor ...................................................................................................... 10
Maintenance Panel Display........................................................................................................ 10
Clearing the Fault History ......................................................................................................... 11
Adjusting the Burner Control Assembly (Printed Circuit Board)......................................... 11
How to Check Manifold Gas Pressure...................................................................................... 12
Program Chip Adjustment.........................................................................................................13
Changing the Maximum Temperature Setting to 140° ........................................................... 14
Changing the Maximum Temperature Setting to 120° ........................................................... 14
Error Codes ................................................................................................................................. 15
Diagnostic Points on Printed Circuit Board............................................................................. 18
Thermistor Resistance Chart.....................................................................................................19
Fan Speed Chart ......................................................................................................................... 20
RTG2-42....................................................................................................................................... 21
Wiring Diagram ........................................................................................................................ 21
Printed Circuit Board ................................................................................................................ 22
RTG 53......................................................................................................................................... 23
Wiring Diagram – RTG 53 ....................................................................................................... 23
Printed Circuit Board – RTG 53 ............................................................................................... 24
RTG 66......................................................................................................................................... 25
Wiring Diagram ........................................................................................................................ 25
Printed Circuit Board ................................................................................................................ 26
Error Code 11 (RTG66 Only)................................................................................................... 26
Error Code 11 (RTG66 Only)................................................................................................... 27
Error Code 51 (RTG 66 Only).................................................................................................. 30
Error Code 61 (RTG 66 Only).................................................................................................. 31
Error Code 65 (RTG66 Only)................................................................................................... 32
Error Code 66 (RTG66 Only)................................................................................................... 33
RTG 74......................................................................................................................................... 34
Wiring Diagram – RTG 74 ....................................................................................................... 34
Printed Circuit Board – RTG 74 ............................................................................................... 35
MIC-180 & EZ Link ................................................................................................................... 36
MIC-180 Printed Circuit Board ................................................................................................ 36
Error Code 03 (MIC-180 & EZLink Only)............................................................................... 37
Test Run Mode.......................................................................................................................... 37
MIC 180 Maintenance Mode Table.......................................................................................... 38
Maintenance Information Mode ............................................................................................... 38
2nd Generation Flame Rod Chart............................................................................................. 39
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Troubleshooting .......................................................................................................................... 40
Troubleshooting Format and Example...................................................................................... 40
Unit Will Not Power On ........................................................................................................... 41
Error Code 00............................................................................................................................ 44
Warning Code 05 ...................................................................................................................... 44
Warning Code 10 ...................................................................................................................... 45
Error Code 11............................................................................................................................ 45
Error Code 12............................................................................................................................ 49
Error Code 13............................................................................................................................ 50
Error Code 14............................................................................................................................ 51
Error Code 15............................................................................................................................ 52
Error Code 16............................................................................................................................ 53
Error Code 21 (Indoor Models Only) ....................................................................................... 53
Error Code 24............................................................................................................................ 54
Error Code 29............................................................................................................................ 54
Error Code 31............................................................................................................................ 54
Error Code 31............................................................................................................................ 55
Error Code 32............................................................................................................................ 55
Error Code 33............................................................................................................................ 56
Error Code 34............................................................................................................................ 56
Error Code 35............................................................................................................................ 57
Error Code 38............................................................................................................................ 57
Error Code 51............................................................................................................................ 57
Error Code 52............................................................................................................................ 58
Error Code 61............................................................................................................................ 59
Error Code 65............................................................................................................................ 59
Error Code 66 (RTG66 Only)................................................................................................... 60
Error Code 71............................................................................................................................ 60
Error Code 72............................................................................................................................ 60
Error Code 76............................................................................................................................ 61
Error Code 79............................................................................................................................ 61
Error Code 80/81....................................................................................................................... 61
Error Code 82............................................................................................................................ 61
Error Code 90............................................................................................................................ 62
Error Code 99............................................................................................................................ 63
Warning Code IL ...................................................................................................................... 63
Warning Code P1...................................................................................................................... 64
Disassembly and Repair – 1st Generation 7.4 product series.................................................. 64
Printed Circuit Board (PCB)..................................................................................................... 64
Air Filter Switch ....................................................................................................................... 65
Water Inlet Solenoid ................................................................................................................. 65
Hot Water Outlet....................................................................................................................... 66
Transformer............................................................................................................................... 66
Fan Assembly............................................................................................................................ 67
Proportional Gas Flow Regulator ............................................................................................. 68
Burner Plate Cover.................................................................................................................... 69
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Burner Assembly ...................................................................................................................... 69
Igniter and Igniter Probes.......................................................................................................... 70
Flame Rod(s)............................................................................................................................. 70
Heat Exchanger Thermistor ...................................................................................................... 70
Parts ............................................................................................................................................. 71
Parts Exploded View for RTG2-42PV and RTG 53PV............................................................ 74
Parts Exploded View for RTG 53X.......................................................................................... 75
Parts Exploded View for RTG 53DV ....................................................................................... 76
Parts Exploded View for RTG 66DV ....................................................................................... 77
Parts Exploded View for RTG 74PV and GT 199PV............................................................... 78
Parts Exploded View for RTG 74DV and GT 199DV ............................................................. 79
Parts Exploded View for RTG 74X and GT 199X................................................................... 80
Before inspecting, diagnosing, repairing or operating any water heater, be sure to examine all of the safety and warning labels on the tank. Follow the instruction on these warning labels. Read and understand the Use and Care Manual that was shipped with the water heater. Failure to do so can result in unsafe operation of the water heater
resulting in property damage, bodily injury, or death. Should you have any problems reading or following the instructions in the Use and Care Manual, seek the help of a licensed and qualified professional.
Copyright 2008, Rheem Manufacturing Company, Water Heater Division.
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Specifications common to all product lines
Model
Purpose Domestic Hot Water (DHW) supply for showers, cleaning and laundry
Rated Gas Input (Btu/Hr.) Modulating
Dimensions See specification sheets for current models and specs
Installation
Working Water Pressure 14 psi minimum; 150 psi maximum Minimum Water Flow 0.66 gallons per minute to turn on burner
Maximum Flow Rate Based on a 45 degree rise; See specification sheets for current models and specs
Gas Connection 3/4" NPT Male Water Connection 3/4" NPT Male
Vent Size
Max. Vent Length See use and care manual for each product type
Inlet Gas Pressure
Hot Water Supply
Electrical
Safety Devices
See specification sheets for current models and specs
See specification sheets for current models and specs
Indoor Wall Mounting - can be vented either horizontally or vertically. Outdoor Wall Mounting - no installed venting required. Direct Vent – uses special concentric venting for indoor installation.
3 or 4" Stainless Steel Venting (Category III); 3/5 or 4/7 Direct Vent Stainless Steel Venting (Category III)
Natural Gas: Min. 4.0" w.c. Max. 10.5" w.c. L.P. Gas: Min. 8.0" w.c. Max. 14.0" w.c.
Factory Setting 100°F (With Supplied UMC-117) Adjusting Range (All second
generation products will go to 140°F out of the box with DIP switch adjustment.)
Max. Setting – Commercial Heavy Duty only
Electrical Rating 120 VAC/60Hz, 3 Amps Wire 3 (three) Pin Power Supply Cord
Fuse
Oxygen Depletion Safety Device (Indoor units only)
Over Heat Limiter for Heat Exchanger
Main Control 100°F - 120°F (140°F)
Bath control 100°F - 120°F
Up to 180°F with dip switch adjustment and UMC Main Remote Control
3A Fuse x 2 (line voltage); 5A fuse on circuit board
Heat Exchanger Thermistor (Boiling Point Safety)
Freeze Protection Minus 30°F (Without Wind-Chill Factor) with power applied
Main Remote Control (UMC-117) Standard
Remote Control
Bath Remote control (USC1-117) optional Second Bath Remote (USC2-117) optional
For the must current specification sheets and use and care manuals, see the website at www.rheemtankless.com.
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Product (Model) History
Implementation
Date
September 2004 RTG42 Initial Tankless Product
May 2005 RTG74 Initial Product Launch n/a n/a Dec 2006 RTG74 Gas Valve change; also
RTG74 Water pipes changed.
Models
Affected
Modification/Upgrade New Parts Board
Programming
n/a n/a
Launch
included new fuel supply tubes from gas valve to burner assembly
Removed the two speed clips from the cold in and water by-pass.
Second Generation
August 2006 RTG2 42 Upgraded product launch on
new chassis No air filter switch n/a n/a RTG 53
series No air filter switch n/a n/a ‘dash one’
RTG74 Added UMC Main remote
Removed 60 minute lockout
Power Restore Auto On
Water flow inlet valve
Allowed all 2nd generation
Sep29 + Oct 2006
New ‘dash
one’ RTG
74
Initial Product Launch n/a n/a
Added EZ link function to all similar models
control as standard to all models; allowed residential units to heat to 1400 F
timer for return circulation function
feature added. Unit resets to last recorded temperature setting
solenoid will close completely when using EZ link cable or MIC 180
units to be installed with MIC 180 RTG 74 chassis only Yes Yes
n/a n/a
EZ link Cable Yes
UMC 117 Main
No Yes
No Yes
No Yes
No Yes
Yes
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Implementation
Date
Flame rod and igniter on
Models
Affected
Modification/Upgrade New Parts Board
Programming
Burner No right hand burner swapped; added a ‘target’ for the spark to hit
Improved burner cover plate Burner cover
No
plate
New programming chip –
all RTG74 models. The new burner plate cover modified the air flow characteristics. This means the chip
Programming
Chips; this is
when the 2
chips in a bag
started.
Yes
programming had to change.
December 5, 2006 Removed transformer. 120v
‘dash two’ model
RTG 74 chassis only Yes Yes
No Yes AC is the primary power source to board
Manifold pressure changed No Yes Programming chip changed
to reflect new manifold
Programming
Chips
Yes
pressures
Moved gas inlet connection
No No to outside the chassis for easier replacement
RTG 53/2-42 chassis New igniter | New wire
Yes Yes harness for igniter | New location
July 1, 2008 RTG 66 Direct Vent model only;
Many Yes altitude configured via dip switch settings; inlet gas pressure check port added
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Sequence of Operations
Action Explanation
Hot water faucet is open creating a demand Hot water draw initiates water flow thru
the machine.
Water flows through the Water Flow Sensor Minimum flow rate of .66 gallons per
minute.
Printed Circuit Board (PCB) senses the flow rate has reached a minimum demand of 0.66 gpm
Fan conducts a pre-purge Pre purge is designed to verify we have a
The Proportional Gas Flow Regulator allows the gas to flow to the main burner
At the same time, the igniter continuously sparks and ignites the main burner
After ignition, the Flame Rods sense and monitor the flame and ensures combustion
The “In Use Indicator” on remote control turns "ON" (Red) and the Priority Indicator
turns Green (multiple remote controls).
The Proportional Gas Flow Regulator Valve continuously adjusts the gas volume in order to maintain the outlet temperature. The water flow sensor also adjusts the proper amount of cold water mix flow to supply a stable hot water temperature at all times. A signal is also sent to the fan motor in order to constantly maintain the correct proportion between the gas volume and air volume.
PCB is the ‘brains’ of the machine and
controls all input and actions during sequence of operations.
clear and clean vent.
PGFR opens to full BTU input initially.
The spark igniter ignites the fuel in the
main burner area. Both left and right burner will fire initially.
The purpose of the flame rods is to verify
flame. In the event of flame failure (or presence when none is expect) the unit will go into an error code.
Main Burner is now lit. The PCB goes thru
a series of calculations (input sensing) to balance out the cold-water temperature, the thermostat setting, the hot outlet temperature and the BTU required to heat the water.
Again, the PCB is constantly monitoring
all of these inputs and actions to ensure the outlet water temperature is within 1 degree of thermostat setting. It also monitors the BTU required to heat the cold water to the thermostat setting and adjusts the gas valve accordingly.
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Action Explanation
(For indoor model only) When the air intake is blocked, or oxygen in a room is not sufficient, the output of the thermocouple that is located in the Oxygen Depletion Sensing Burner (ODS) will change.
The PC Board senses this change and
controls the Fan and Proportional Gas Control Valve in order to prevent imperfect combustion. If the control board cannot correct such condition, the unit will go into an error code.
When the hot water tap is closed, the flow rate
Gas valve is closed. Main burner shuts off.
signal from water flow sensor stops.
The fan conducts a post purge. The purpose of the post purge is to cool the
heat exchanger.
Sensors and Safety
Oxygen Depletion Sensing System Operation
Oxygen Depletion Safety Device (ODSD) Sensing Burner - Indoor Model Only
The sensing burner is a primary air type ceramic burner that consists of an outer jacket surrounding the flame opening and a thermocouple to detect flame temperature. The sensing burner is located in the part of the main burner and designed to monitor the flame condition at all times. In case the oxygen level decreases due to blocked or clogged air intake or flue venting or by contaminated air (not enough oxygen content), location of the flame, as well as its temperature, will change. This change will be detected by the ODSD thermocouple.
The unit will attempt to resolve the problem on its own by adjusting the quantity of fuel and adjusting the fan speed. During this resolution period, the unit will show a flash code of 05 and have an audible alarm. In the event the unit cannot fix the fuel air mixture, the unit will shut down with a flash code of 13.
Here is how the ODS sensing system works.
1 Is the ODS thermocouple detecting normal
temperatures?
No 2 Printed Circuit Board (PCB) will increase the
airflow rate to balance the air-fuel mixture.
3 Is the ODS thermocouple detecting normal
temperatures?
Yes Unit is operating normally. ODS Thermocouple
will detect proper temperature with 2 minutes on a cold start and within 1 minute on a warm start.
PCB automatically tries to fix the problem with
increased airflow.
Yes Unit is operating normally.
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No 4 Second attempt by the PCB to increase the
airflow rate to balance the air-fuel mixture.
5 Is the ODS thermocouple detecting normal
temperatures? No 6 Third attempt by the PCB to increase the airflow
rate to balance the air-fuel mixture.
7 Is the ODS thermocouple detecting normal
temperatures? No 8 Final attempt by the PCB to increase the airflow
rate to balance the air-fuel mixture.
PCB continues to try to fix the air-fuel mixture
my adding airflow. It now adds a visual alarm on the Remote Control by flashing both the red and green indicators.
Yes Unit is operating normally.
PCB continues to try to fix the air-fuel mixture
by adding airflow. It now adds an audible alarm on the Remote Control by sounding a tone every 60 seconds and flashes a monitor code of 05.
Yes Unit is operating normally.
If the unit does not detect normal ODS
thermocouple temperatures, then unit will shut down with an error code of 13.
NOTE
Shutdown by imperfect combustion can be reset by pressing power switch (ON/OFF Button). If shutdown occurs 5 times within 4 hours, the water heater will not recover for the next 4 hours.
How to Reset the Four (4) Hour ODS Timer
1. Turn the unit OFF. Remove the front cover. Locate the dip switches on the control board.
2. Make sure all the dip switches are OFF (down position).
3. Locate the #2 dip switch and turn it ON (up position) then immediately turn it off.
4. Within 5 seconds, press and hold both the MIN and MAX button for at least 2 seconds.
5. The remote control will flash briefly. This is your signal that the fault history has been cleared.
6. You can operate the machine.
Overheat Film Wrap
The Overheat Film Wrap detects the heat exchanger if and when it overheats. The over heat limiter is the plastic film wrap with the black squiggly lines.
It constantly monitors the heat exchanger temperature and will show an Error Code 14 in the event the heat exchanger gets too hot.
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g
Heat Exchanger Thermistor
The Heat Exchanger Thermistor monitors the temperature of the water inside the heat exchanger. It will activate to Error Code 15 if the water temperature exceeds 207º F for more than 15 seconds; or 230º F for more than 1 second. It will also show an Error Code 32 if the thermistor is disconnected from the circuit board.
Maintenance Panel Display
The Rheem Tankless has a Maintenance Display chart on the remote control panel. To access the Maintenance Display, turn the unit OFF. Then hold down the UP and DOWN arrow keys at the same time for a few seconds. You will hear an audible beep and see the display go to 0E. By pressing the UP and DOWN arrow keys on the remote display, you can access a variety of information about the machine. For Example a code at 3E (recent faults) may display as 21 (Error Code 21).
Shortcut: Lift dip switch #1 to the up position to go immediately into maintenance mode.
First Digit – Use DOWN (▼)arrow key on Remote Control
0* 1* 2* 3* 4* 5* 6* 7* 8* 9*
*E Null Fault Codes of the most recent 8 faults Null
*F Null Sequence Number of the most recent 8 faults Null *C Total combustion times until recent error fault (** x 10000times) Null *D Total combustion times until recent error fault (** x 100 times) Null *H Total combustion period until recent error fault (** x 1000 hours) Null *J Total combustion period until recent error fault (** x 10 hours) Null
*Y
Status
Flame Rod
GPM Flow Rate
*A
Thermo
Electromot
ive Force
Second Digit – Use UP (►) arrow key on Remote
Control
Control
You can turn the unit on while in Maintenance Mode by quickly pressing the ON/OFF button one time. The temperature will default to 120 degrees and will not display because you are still in Maintenance Mode. If you demand hot water, the unit will fire off and you will be able to read the “Y” line in real time. That means you will see the actual flow rate in gallons per minute, the cold-water inlet temperature, the hot water outlet temperature, heat exchanger temperature, and flame rod status.
(*.* gpm)
e
Line
Volta
Thermistor
Ambient Air
Fan
Detective
Temperature
Cold Water Inlet
Value
Thermistor
Temperature
Heat Exchanger
Fan Motor
Current
10
Null
Thermistor
Temperature
Hot Water Outlet
Null
Thermistor
Temperature
Null
RPM
Power for
Fan Speed x 100
P.G.F.R. valve
Null
Null
Null
Sequence
Null
Number
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Clearing the Fault History
1. Turn the unit OFF. Remove the front cover. Locate the
dip switches on the control board.
2. Make sure all the dip switches are OFF (down
position).
3. Locate the #1 dip switch and turn it ON; then turn it
OFF.
4. Within 5 seconds of turning the dip switch off, press
and hold the MIN (SW1) or MAX (SW2) button for at least 2 seconds.
5. The remote control will flash briefly. This is your
signal that the fault history has been cleared.
6. You can verify clearing of fault history by entering Maintenance Mode and check the
code at location 1E. It should read NULL or ┌┐.
Adjusting the Burner Control Assembly (Printed Circuit Board)
The purpose of this procedure is the balance the fuel pressure and air volume at the burner manifolds. This procedure will ensure that you get optimal performance of the modulating characteristics of the unit by allowing firing rates between 19,000 BTU (minimum) and 199,900 BTU (maximum).
WARNING: You will need to perform this procedure when you replace the PCB or install a new altitude chip. Without the adjustment, the water heater may not function properly.
When replacing the printed circuit boards adjust as follows.
Measurement of Fan Pressure:
Measure the fan pressure before adjusting the burner manifold pressure. The fan pressure differs depending on models, types of gas and installation condition. Measure the fan pressure at each installation site.
1. Measurement of "Minimum" Capacity a. Without opening the hot water tap, push the “SW1" b. Using the manometer, measure and record the pressure (in. w.c.).
2. Measurement of "Maximum" Capacity a. Without opening the hot water tap, push the "SW2" Button on PC Board. b. Using the manometer, measure and record the pressure (in. w.c.).
Adjustment of Burner Manifold Pressure:
NOTE: Always start from "Minimum" when adjusts the burner manifold pressure. The display is on remote control. Always connect the remote control to monitor this procedure.
1. Adjustment of "Minimum" capacity a. Open the hot water tap gradually until the water heater ignites at the minimum
Button on PC Board.
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N
N
operating water flow.
b. Push the Adjusting Button on the PC Board. [LH] is displayed on the LED of
remote control.
c. Hold the Adjusting Button; push the "SW1" button on the PC Board. The
current number [01 - 39] is displayed on the LED of remote control.
NOTE: Every time you press the MIN button, the display will cycle up to the number 39. Once it reaches 39, it will automatically reverse and cycle back down to 1.
d. You can change the gas pressure by pushing the "SW1" button. Using the
manometer, adjust the minimum manifold pressure to the standard pressure plus the measured minimum fan pressure.
e. Rel ease the "SW1" button.
2. Adjustment of "Maximum" capacity a. Open the hot water tap fully to allow the water heater to ignite a maximum
operating flow. You may need to turn on up to three fixtures to get max water flow.
b. Push the Adjusting Button on the PC Board. [LH] is displayed on the LED of
remote control.
c. Hold the Adjusting Button; push the "SW2" Button on the PC Board. The current
figure [01 - 39] is displayed on the LED of remote control.
d. You can change the test gas pressure by pushing the "SW2" button every time.
Using the manometer, adjust the minimum manifold pressure to the standard pressure plus the measured maximum fan pressure.
e. Release the "SW2" button.
Note: If [EE] is displayed on the LED of remote control, adjust again with caution. This means there was an error in the adjustment sequence.
How to Check Manifold Gas Pressure
When the “MAX” or “MIN” button is pushed, the combustion is fixed at the respective firing rate. The LED of remote control displays 1L (minimum combustion) or 3H (maximum combustion).
The adjusted manifold pressure must be as follows.
RTG74-Indoor
AT. Gas 2.52+ fan pressure (max.) 0.45+ fan pressure (min.)
L.P. Gas 7.36+ fan pressure (max.) 1.22+ fan pressure (min.)
RTG74 -Outdoor MAX. (in. w.c.) MIN. (in. w.c.)
AT. Gas 2.32+ fan pressure (max.) 0.43+ fan pressure (min.)
L.P. Gas 6.61+ fan pressure (max.) 1.10+ fan pressure(min.)
Second Generation Product Fan Speeds
42PVP 2nd 2.52 + fan pressure (max.) 0.45 + fan pressure (min.)
42PVN 2nd 2.36 + fan pressure (max.) 0.45 + fan pressure (min.) 53PVP 3.50 + fan pressure (max.) 0.45 + fan pressure (min.) 53PVN 3.46 + fan pressure (max.) 0.45 + fan pressure (min.)
MAX. (in. w.c.) MIN. (in. w.c.)
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53XP 3.46 + fan pressure (max.) 0.55 + fan pressure (min.) 53XN 2.83 + fan pressure (max.) 0.49 + fan pressure (min.) 53DVP 3.01 + fan pressure (max.) 0.37 + fan pressure (min.) 53DVN 2.95 + fan pressure (max.) 0.39 + fan pressure (min.) 74DVP 7.28 + fan pressure (max.) 1.15 + fan pressure (min.) 74DVN 2.36 0.42 + fan pressure (min.)
Program Chip Adjustment
To quickly establish someone’s altitude with zip code use the following link. Type the zip code in the upper left hand corner and hit enter, it will bring up current weather conditions and include the altitude.
http://www.wunderground.com/
When the water heater is installed above 3,280 feet, adjustment of the Program Chip is required. Without adjusting the Program Chip, the water heater may not function properly. If the water heater is installed less than 3,280 feet, no Program chip is required or supplied and no action is necessary. A different Program chip is required for every 3,280 feet. The Program chip is not interchangeable between Indoor and Outdoor models or types of gas.
1. Check the altitude (above sea level) where the water heater is installed.
2. Ensure that you have the correct Program chip for proper model, gas type and altitude.
3. Disconnect the electric power to the water heater. Turn off the gas shutoff valve and
water shutoff valve.
4. Remove the front cover.
5. Place Program Chip as shown on PCB.
6. Turn on the electric power.
7. Find the DIP Switch #1 and #2 located at the top left hand side of the PCB.
8. Change the DIP Switch #1 and #2 setting to the "ON" position. DO NOT alter any other
DIP Switch.
9. The LED on the PCB is flashing. At the same time, the display of the remote control
starts to flash.
10. Find the Adjusting Button located at the top left hand side of the PCB.
11. Press the Adjusting Button on the PCB. The display of the PCB and the remote control
changes from "Flashing" to "Illuminating".
12. Change the Dip Switch #1 and #2 setting to the "OFF" position. DO NOT alter any other
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DIP Switch. The LED on the PCB and the display of the remote control stops illuminating.
13. Attach the unit's front cover.
14. Turn on the gas shutoff valve and water shutoff valve.
15. Check and ensure safe operation and performance of the water heater.
Changing the Maximum Temperature Setting to 140°
By installing the UMC- Main Remote Control, you can adjust the maximum temperature setting to 140 degrees F. Water temperature settings of 130°F and 140°F can be achieved only when using MAIN remote control. The water temperature is set at 100°F from the factory.
To adjust the unit to create water temperatures from 130 or 140 degrees, you must perform a DIP Switch adjust as follows:
1. Turn off remote control. Leave the unit
plugged into a 120 VAC power source.
2. Turn off the gas and water shutoff
valves.
3. Remove the front cover.
4. Find the DIP Switch #4 located at the top
left hand side of the PCB.
5. Change the DIP Switch #4 setting to the
"ON" position. DO NOT alter any other DIP Switch.
6. The LED on the PCB is flashing. At the same time, the display of the Main Remote
Control starts to flash.
7. Press the "SW2" Button on the left hand side of the PCB for more than 1 second.
8. The LED on the PCB starts illuminating continuously. At the same time, the display of
the Main Remote Control is on continuously.
9. Change the DIP Switch #4 setting back to the "OFF" position. DO NOT alter any other
DIP Switch.
10. The LED on the PCB will stop illuminating. At the same time, the display of the Main
Remote Control will turn off.
11. Attach the unit's front cover.
12. Turn on the remote control, gas and water shutoff valves.
13. Check and ensure safe operation and performance of the water heater.
Changing the Maximum Temperature Setting to 120
Follow the instruction below if it is determined that a setting of 130°F or 140°F is no longer required and you want to return to a maximum water temperature of 120°.
°
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1. Turn off remote control. Leave the unit plugged into a 120 VAC power source.
2. Turn off the gas and water shutoff valves.
3. Remove the front cover.
4. Find the DIP Switch #4 located at the top left hand side of the PCB.
5. Change the DIP Switch #4 setting to the "ON" position. DO NOT alter any other DIP
Switch. The LED on the PCB is on. At the same time, the display of the Main Remote Control is on continuously.
6. Press the "SW1" Button on the left hand side of the PCB for more than 1 second. The
LED on the PCB starts flashing. At the same time, the display of the Main Remote Control starts to flash.
7. Change the DIP Switch #4 setting back to the "OFF" position. DO NOT alter any other
DIP Switch. The LED on the PCB will stop flashing. At the same time, the display of the Main Remote Control will turn off.
8. Attach the unit's front cover.
9. Turn on the remote control, gas and water shutoff valves.
10. Check and ensure safe operation and performance of the water heater.
Error Codes
Code Fault Remedy
1 Hour continuous combustion
00
(First generation products only – mfg date thru Jul 06)
MIC 180 and EZ Link Only Check communications cable.
03
Imperfect Combustion Alarm Clean air inlet filter.
05
Warning or Predictive Code –
10
not a fault code.
Air Supply or Exhaust Blockage
No Ignition Ensure you have gas to the appliance and valves are turned ON.
11
Flame Failure (had main burner,
12
then lost it)
Close all hot water taps to reset unit. Turn off, or remove circulation pumps (unit is not designed for continuous operation with circulation systems).
Check #4 dip switch setting to ON position.
Clean combustion air fan. Clean heat exchanger fins. Check for adequate combustion air ventilation openings and clean if necessary. Check vent system for partial blockage and correct as necessary.
Check all vent components for proper connections. Check that nothing is blocking the flue inlet or exhaust. Ensure condensation trap/drain was installed correctly. Ensure heat exchanger fins, fan, and air intake are not blocked.
Ensure gas type and pressure is correct. Bleed all air from gas lines. Ensure gas line, meter, and regulator are sized properly. Ensure appliance is properly grounded. Check gas solenoid valves for open or short circuits. Ensure igniter is operational. Check igniter wiring harness for damage.
Ensure gas type and pressure is correct. Bleed all air from gas lines. Ensure flame rod wire is connected. Check flame rod for carbon build-up. Ensure gas line, meter, and regulator are sized properly.
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Ensure appliance is properly grounded. Check gas solenoid valves for open or short circuits. Check power supply for proper voltage and voltage drops. Disconnect remote control; see if it runs. Disconnect and re-connect all wiring harnesses on unit and PC board.
Oxygen Depletion Sensor (Poor
13
or Improper Combustion)
Overheat Wrap Fault Ensure high fire and low fire manifold pressure is correct.
14
Boiling Safety Device Check for closed water heater inlet valve or restrictions in cold water
15
Over Temperature Warning Check for clogged heat exchanger.
16
Malfunction of Air Intake Filter
21
Switch (Indoor Products Only)
Malfunction of Operational
24
Switch
Heat Exchanger Outlet Temp.
29
Too Low
Water Inlet Temperature Sensor
31
Fault
Heat Exchanger Temperature
32
Sensor Fault
Outgoing Water Temperature
33
Sensor Fault
Combustion Air Temperature
34
Sensor Fault
Improper Thermistor
35
Connection
ODS Sensor has malfunctioned. The sensor itself is not responding to a self check from the printed circuit
38
Gas Inlet Solenoid Valve Fault Check gas inlet solenoid valve wiring harness for loose or damaged
51
Ensure there is plenty of fresh air to the unit. Unit needs 1 square inch for each 1,000 BTU of input. That is up to 200 square inches or a space 14 ½ x 14 ½ inches.
Check gas type of unit and ensure it matches gas type being used. Check heat exchanger for cracks and/or separations. Check for improper program chip. Check for restrictions in airflow around unit and vent terminal.
inlet pipe (must be fully open). Check for clogged heat exchanger (scale buildup). On commercial water heater, lower set point temperature below 180 high altitude.
Check for restrictions in airflow around unit and vent terminal.
Make sure air filter door is properly seated. Make sure front panel is properly installed.
Disconnect remote control and retry. Verify unit is electrically grounded. Press max button on PCB to reset; Press min button on PCB to reset.
Clean air inlet screen. Clean heat exchanger fins
Check sensor wiring for damage. Ohm out sensor Check and clean scale from sensor.
Check sensor wiring for damage. Ohm out sensor Check and clean scale from sensor.
Check sensor wiring for damage. Ohm out sensor Check and clean scale from sensor.
Check sensor wiring for damage; Ohm out sensor Check and clean ambient air temperature sensor. Ensure fan blade is tight on motor shaft and it is in good condition. Check for restrictions in airflow around unit and vent terminal.
Check that all thermistors are connected to proper connections on PCB.
board. Check wiring harness. Check for proper voltage to ODS
terminals. Ohm out solenoid valve.
0
F at
16
Page 18
52
61
65
66
71
72
76
79
80, 81
82
90
99
No
code
Modulating Solenoid Valve Fault
Combustion Fan Failure Ensure fan motor will turn freely. Motor will operate with a small
Water Volume Control Fault Check water flow solenoid valve wiring harness for loose or damaged
Water By-Pass Control Fault Check water by-pass solenoid valve wiring harness for loose or damaged
Gas Inlet Solenoid Valve Control Fault
Flame Sensing Device Fault Ensure flame rod is touching flame when unit fires.
Communication Fault with Remote Control
Fan Motor Current Fault Ensure fan motor will turn freely. Motor will operate with a small
Gas Cut-off Failure Ohm out all solenoid valves.
PCB data failure. Control board is not programmed.
Blocked Flue Fault Clean any blockage in heat exchanger, combustion fan, inlet filter, and
Fan Motor cannot vent Clean Air Inlet Screen; Clear vent blockages
Nothing happens when water is flowing through unit.
Check modulating gas solenoid valve wiring harness for loose or damaged terminals. Ohm out solenoid valve.
amount of restriction. Check wiring harness to motor for damaged and/or loose connections. Check venting length not to exceed max lengths and bends.
terminals. Check for proper voltage to water flow solenoid.
terminals. Check for proper voltage to water by-pass solenoid
Check gas inlet solenoid valve wiring harness for loose or damaged terminals. Ohm out solenoid valve.
Check inside burner chamber for any foreign material blocking flame at flame rod. Check all wiring to flame rod for damage. Check flame rod for proper voltage. Remove flame rod and check, clean with steel wool.
Check remote control wiring for loose or damaged connections. Bypass remote control cable by connecting remote control directly to remote control terminals on PCB. Replace cable if found to be faulty.
amount of restriction. Check fan motor for proper voltage and for water (condensation) damage
Check voltage of all flame rods.
Program PCB for proper altitude and fuel type circuit board with proper programming chip.
exhaust flue.
Check for blocked heat exchanger
Make sure unit is connected to proper power supply and circuit breakers are on. Clean inlet water supply filter. Ensure you have at least the minimum flow rate required to fire unit. On new installations ensure hot and cold water lines are not crossed.
17
Page 19
Diagnostic Points on Printed Circuit Board
Measurement Point
Connection Wire Color
I – J AC 90 – 110V Do you have power to the control board? U W1 – W2 50K Ω – 500K Ω Is the Over Heat Film Wrap OK?
BR1 – BK2 DC 2 - 5V (pulse)
S
R3 – BK2 DC 11 – 17 V Does the water flow sensor have voltage?
B4 – W6 DC 120 – 160 V Does the fan motor have the proper voltage?
G
R W6 – BK3 680F = @ 10.3 KΩ Is the cold water inlet thermistor working? R Y5 – BK3 1040F = @ 4.9 KΩ Is the heat exchanger thermistor working? R R4 – BK3 1040F = @ 4.9 KΩ Is the hot water outlet thermistor working? R B7 – BK3 680F = @ 10.3 KΩ Is the ambient air thermistor working? R R1 – BK2 DC 1.5 - 14 V
L R1 – GND AC 1 – 100 V M W1 – GND AC 1– 100 V T B1 – GND AC 1 – 100 V Flame Rod 1 is the white wire and goes to the right front half burner. Flame Rod 2 Flame Rod 3 H GY2 – GY5 AC 90 - 110 V Is the igniter working properly All models except RTG66: These are the two green wires at connector H. They are the two green wires to the by by-pass solenoid on the water flow valve. When the cold water bypass solenoid is closed, must be 0 volts DC. (Remote set at 118F ~ 180F). When the cold water bypass opens, voltage reads about 80 volts DC. (Remote is set to 100F~116F). K Y1- BK5 DC 75 - 100 V
K W2- BK5 DC 75 - 100 V
K R3- BK5 DC 75 - 100 V
K B4- BK5 DC 75 - 100 V
B
R3 – B4 DC 12 - 18 V Does the fan motor have proper voltage? Y1 – B4 DC 4 – 10 (Pulse) Is the fan motor producing a regular pulse?
is the red wire and goes to the right rear half burner. is the blue wire and goes to the left burner. (74 series only)
W2 – BK8 DC 8 – 16V Does the water volume control motor have
R7 – BK8 DC 8 – 16V Does the water volume control motor have
GR6 – BK8 Less than 1V DC
Normal Value What you are checking?
Does the water flow sensor send a pulse? More than 1,310 pulses/minute is nominal.
40 – 80Ω
.8 – 2.2. KΩ
.8 – 2.2. KΩ
.8 – 2.2. KΩ
.8 – 2.2. KΩ
(Limiter on) DC4 – 6 V (Limiter Off)
(Only when water is flowing thru control)
(Power ON; no water flow)
Is the P.G.F.R. valve operating?
(Proportional Gas Flow Regulating Valve)
Are the three flame rods detecting flame?
Is the solenoid (SV0) working?
(Primary fuel inlet to gas valve)
Is the solenoid valve (SV1) working?
(Fuel to ODS and front right burner)
Is the solenoid valve (SV2) working?
(Fuel to back right burner)
Is the solenoid valve (SV3) working?
(Fuel to left side burner)
proper voltage?
proper voltage?
Is the water volume control switch OK?
18
Page 20
Q R1 – W2 DC8 – 30V
(measured 2 minutes after combustion startup)
P 1 – 2 DC8 – 30V
(measured 2 minutes after combustion startup)
O W1 – W2 Less than 1V DC;
Less than 1Ω
Is the thermo-electromotive force OK?
Is the air intake switch working?
Thermistor Resistance Chart
°F
Temp
KΩ
Resistance
32 23.73 77 8.494 122 3.485 167 1.598
33.8 22.706 78.8 8.177 123.8 3.371 168.8 1.552
35.6 21.733 80.6 7.873 125.6 3.262 170.6 1.508
37.4 20.806 82.4 7.583 127.4 3.156 172.4 1.465
39.2 19.925 84.2 7.304 129.2 3.055 174.2 1.424 41 19.085 86 7.037 131 2.957 176 1.384
42.8 18.286 87.8 6.781 132.8 2.863 177.8 1.345
44.6 17.525 89.6 6.536 134.6 2.773 179.6 1.307
46.4 16.799 91.4 6.302 136.4 2.686 181.4 1.271
48.2 16.108 93.2 6.076 138.2 2.602 183.2 1.236
50 15.449 95 5.86 140 2.52 185 1.202
51.8 14.82 96.8 5.653 141.8 2.442 186.8 1.169
53.6 14.221 98.6 5.454 143.6 2.367 188.6 1.137
55.4 13.469 100.4 5.264 145.4 2.295 190.4 1.106
57.2 13.104 102.2 5.081 147.2 2.225 192.2 1.077 59 12.583 104 4.905 149 2.157 194 1.048
60.8 12.086 105.8 4.736 150.8 2.092 195.8 1.02
62.6 11.611 107.6 4.574 152.6 2.029 197.6 0.993
64.4 11.157 109.4 4.418 154.4 1.968 199.4 0.966
66.2 10.723 111.2 4.269 156.2 1.91 201.2 0.941
68 10.309 113 4.125 158 1.853 203 0.916
69.8 9.913 114.8 3.987 159.8 1.799 204.8 0.893
71.6 9.534 116.6 3.854 161.6 1.746 206.6 0.869
73.4 9.172 118.4 3.726 163.4 1.695 208.4 0.847
75.2 8.826 120.2 3.603 165.2 1.646 210.2 0.825
°F
Temp
KΩ
Resistance
°F
Temp
KΩ
Resistance
°F
Temp
Resistance
KΩ
19
Page 21
Fan Speed Chart
20
Page 22
RTG2-42
Wiring Diagram
21
Page 23
Printed Circuit Board
22
Page 24
RTG 53
Wiring Diagram – RTG 53
23
Page 25
Printed Circuit Board – RTG 53
24
Page 26
RTG 66
Wiring Diagram
25
Page 27
Printed Circuit Board
The RTG 66 PCB has two set of dip switches. Dip Switch set #2 controls the high altitude settings. See the use and care manual for instructions.
The procedures for changing the maximum temperature set point have also changed. See the use and care manual for instructions.
26
Page 28
y
g
Error Code 11 (RTG66 Only)
Explanation: No ignition. This error code can be cause one three different scenarios. Please match the scenario to the fault condition before you troubleshoot. At a minimum check the following in all cases:
1. Ensure you have gas to the appliance.
2. Bleed all air from gas lines.
3. Ensure appliance is properly grounded.
4. Ensure gas line, meter, and regulator are sized properly.
5. Ensure gas type and gas pressure to the machine is correct.
6. Flex lines with a full 3/4 inch inside diameter may also restrict fuel flow enough to give
you error code 11. We do not condone the use of flex line gas piping with tankless.
Scenario 1 – Error Code 11; fan is operating; igniter does not spark.
Does the igniter
have voltage?
Yes
Is the igniter electrode clean? Is the electrode damaged? Is wirin
intact?
Yes
Remove the burner cover plate to inspect the igniter.
Replace Igniter Assembl
Scenario 2 – Error Code 11; fan is operating; igniter does spark; main burner does not ignite.
Does the Gas
Inlet Solenoid
Valve #0 have a
voltage?
Yes
No
Replace Printed Circuit Board
Measure the voltage of connector I between both gray wires: 108 to 132 VAC.
You will need to cycle the unit to initiate an ignition attempt to conduct this test.
No
Clean/replace igniter electrode. Verify good ground.
No
Replace Printed Circuit Board
Measure the voltage of connector K between Black and Yellow wires: 90 to 120 VDC
27
Page 29
N
Does the
Solenoid Valve
#1 have a
voltage?
Yes
No
Replace Printed Circuit Board
Measure the voltage of connector K between Black and White wires: 90 to 120 VDC
Does the
Solenoid Valve
#2 have a
voltage?
Yes
No
Measure the voltage of connector K between Black and Red wires: 90 to 120 VDC
Replace Printed Circuit Board
Does the
Solenoid Valve
#3 have a
voltage?
Yes
No
Replace Printed Circuit Board
Measure the voltage of connector K between Black and Blue wires: 90 to 120 VDC
Does the
P.G.F.R. valve
have a voltage?
o
Replace Printed Circuit Board
Yes
Measure the voltage of connector R between Black#2 and Red#1 wires:
1.5 to 14 VDC
28
Page 30
y
y
y
y
y
Is the resistance
of the Gas Inlet Solenoid Valve
OK?
Yes
No
Replace Gas Control Ass
Measure the resistance of connector K between Black and Yellow wires:
0.8 to 2.4k Ohms
Is the resistance
of the Solenoid
Valve #1 OK?
No
Replace Gas Control Ass
Yes
Measure the resistance of connector K between Black and White wires:
0.8 to 2.4k Ohms
Is the resistance
of the Solenoid
Valve #2 OK?
No
Replace Gas Control Ass
Yes
Measure the resistance of connector K between Black and Red wires:
0.8 to 2.4k Ohms
Is the resistance
of the Solenoid
Valve #3 OK?
No
Replace Gas Control Ass
Yes
Measure the resistance of connector K between Black and Blue wires:
0.8 to 2.4k Ohms
Is the resistance
of the
Proportional
Gas Control
Valve OK?
Yes
No
Replace Gas Control Ass
Measure the resistance of connector R between Black#2 and Red#1 wires: 40 to 80 Ohms
Check or replace main burner
29
Page 31
C
r
y
)
y
Scenario 3 – Error Code 11; main burner ignites, but shuts off after ignition.
Display maintenance information 0
Try to ignite main burne
Does the 0y
display indicate
any remaining
flame?
No
Is there any
flame current?
No
Clean or replace main burner and Flame Rod Electrode
Yes
Refer to Error code 12 procedures
Yes
Replace Printed Circuit
Measure the electric current of Flame Rods connector M between white wire and ground: 1 to 100 VA
Flame Rod Status: X=not detecting flame; O=is detecting flame
Flame Rod 1(white) X O
Flame Rod 1 is the white wire at connector M and goes to the burner. Normal flame rod status in the control panel with the burner on should be 01
0y display 00 01
Error Code 51 (RTG 66 Only)
Explanation: Gas Inlet Solenoid Valve fault. At a minimum check the following:
1. Check gas valve wiring harnesses for loose or damage terminals
2. Check connections to the circuit board are tight.
Cycle the heater two times by turning off – then on – at 10 second intervals.
Is there any
remaining
flame thru the
view window?
No
Display Maintenance Information 0y (flame rod status
Yes
Replace Gas Control Assembl
30
Page 32
Does the 0y
display indicate
any remaining
flame?
Yes
Flame Rod Status: X=not detecting flame; O=is detecting flame
Flame Rod 1(white) X O
Flame Rod 1 is the white wire at connector M and goes to the burner. Normal flame rod status in the control panel with the burner on should be 01 or detecting flame.
No
The water heater seems to be normal. Try to operate again
Pull out the relay connection of flame rod connector (M) and then display maintenance information [0y].
Does the 0y
display indicate
any remaining
flame?
No
Yes
Replace Printed Circuit Board
0y display 00 01
Clean or replace Main Burner and Flame Rod Electrodes
Error Code 61 (RTG 66 Only)
Explanation: Combustion Fan failure. Fan motor does not work properly. At a minimum check the following:
1. Ensure fan motor will turn freely.
2. Check if there is some volume of air from the flue outlet at the top of
the heater.
3. Check wiring harness to motor for damaged and/or loose connections.
4. Check Molex connection of the PCB.
Does the Fan
operate?
Yes
No
Does the Fan
Yes
Motor have
sufficient
voltage?
No
Replace Printed Circuit Board
Measure the voltage of connector G between Black and Red wires: 144 to 192 VDC If you accidentally cross the BLACK and RED wires with your multimeter leads, you will short out the circuit board and the fan
31
Page 33
y
(p
y
The water heater appears to be normal. Attempt to operate again.
Replace Printed Circuit Board
Is there any
pulse output
from the Fan
Motor?
Yes
No
Replace Fan Assembl
Is there any pulse output from the Fan Motor? To measure the pulse output, turn on the fan by pushing "MAX" (SW2) Button. Measure the voltage of connector G between Blue and Yellow wires: 4 to 10 VDC
ulse)
Error Code 65 (RTG66 Only)
Explanation: Water Volume Control fault. At a minimum check the following:
1. Verify there is water flow thru the unit even if the unit does not fire.
2. Access maintenance information to determine flow rate.
3. Check all wiring connections to the water control and connector B on the Printed Circuit
Board.
Turn power off; unplug unit and
then on again.
Yes
When motor
operates, is the
voltage to the
water control
OK?
Measure the voltage at connector C between the White#2 and Black#8 wires for: 8 to 16 VDC
Replace the Water Control Assembl
Is the voltage to
the water
control OK?
No
Replace the Printed Circuit Board
No
Replace the Printed Circuit Board
Measure the voltage at connector C between the Red#7 and Black#8 wires for: 8 to 16 VDC
32
Page 34
y
Error Code 66 (RTG66 Only)
Explanation: Water By-Pass Control fault. At a minimum check the following:
1. Verify there is water flow thru the unit even if the unit does not fire.
2. Access maintenance information to determine flow rate.
3. Check all wiring connections to the water control and connector B on the Printed Circuit
Board.
Turn power off; unplug unit and
then on again.
Yes
When motor
operates, is the
voltage to the
water control
OK?
Measure the voltage at connector B between the Red#7 and Black#8 wires for: 8 to 16 VDC
Replace the Water Control Assembl
Is the voltage to
the water by-
pass control
OK?
No
Replace the Printed Circuit Board
No
Replace the Printed Circuit Board
Measure the voltage at connector B between the Red#7 and Black#8 wires for: 8 to 16 VDC
33
Page 35
RTG 74
Wiring Diagram – RTG 74
A wiring diagram is also located on the inside of the front cover panel.
34
Page 36
Printed Circuit Board – RTG 74
35
Page 37
MIC-180 & EZ Link
There are two kinds of communications cables when manifolding multiple tankless units. If only two like units are connected together, we call that EZ Link. This process uses a single 6 foot long cable with four colored wires at each end. You can recognize the EZ Link cable by the yellow wire at each end. These cables may be plugged in either way.
The other manifolding process uses the MIC-180 control panel to connect up to 20 tankless units at a time. These communications cables come in multiple lengths and have one end of the cable with a single red, white and black wire. These cables must be plugged in a certain way for the system to communicate properly. Plug the 3-wire end into the tankless water heater; plug the other (4-wire) end into the MIC-180 control board.
MIC-180 board Tankless heater board
MIC-180 Printed Circuit Board
36
Page 38
Error Code 03 (MIC-180 & EZLink Only)
Explanation: Manifold Control Failure. The unit has lost the communications link between itself and the MIC-180; or between the two units with EZLink.
At a minimum check the following:
1. Verify the communications cable is plugged into
the printed circuit boards on the water heaters and the MIC-180.
2. Verify #4 Dip Switch is in the ON position for
each water heater in the manifold.
Turn power off. Unplug the communications cable from all units. Turn each unit ON (one at a time) and make an attempt for main burner. We are trying to see if each unit works without the communications cable links. If a unit does not go to main burner, then troubleshoot that unit. Then, one at a time, reconnect the communications cable and go main burner.
Did the unit go
to main burner?
Yes
Everything appears to be normal.
No
Replace the Printed Circuit Board Replace communications cable
Conduct continuity check of the communications cable.
Test Run Mode
1. Remove the front cover of the manifold controller.
2. Change the DIP switch #1 setting on the main
communication PCB to “ON” position (UP). DO NOT alter any other DIP switch.
3. By pressing the SW2 button located below the LED display on the main communication
PCB, the number of the water heater to be tested can be selected. The left two digits flashing on the LED display of the main communication PCB indicates the number of the water that has been selected.
37
Page 39
4. Press the SW3 button on the main communication PCB to change to trial operation mode.
The left two digits of the LED display will indicate the water heater selected and will illuminate continuously. At the same time, the LED lamp on the main communication PCB or the extended communication PCB corresponding to the water heater selected will illuminate and indicate the water heater is in trial operation mode.
5. Open the hot water outlet. Check and ensure safe operation and performance of the water
heater selected.
6. Change the DIP switch #1 setting to the “OFF” position (DOWN) to end the trial operation
mode.
7. To choose different water heater for trial operation repeat steps 3 through 6.
MIC 180 Maintenance Mode Table
SW3 Item Number
0 1 2 3 4 5 6 7 8 9 E PC Version Error code for n time ago Not in use F Not in use Sequence number for n time ago Not in use C Upper digits of
total times of
combustion d Lower digits of
SW2 Group Number
total times of
combustion H Upper digits of
total duration of
combustion J Lower digits of
total duration of
combustion Y Not in use Not in use Not in use A Not in use Not in use Sequence
Upper digits of the number of occurrence of combustion at the time of error n times ago (X10000) Lower digits of the number of occurrence of combustion at the time of error n times ago (X100)
Upper digits of the duration of combustion at the time of error n time ago (X1000)
Lower digits of the duration of combustion at the time of error n time ago (X10)
Not in use
Not in use
Not in use
Not in use
number on the Control Board
Maintenance Information Mode
1. DIP switch #1 on the Unit Number Control Board to the “ON” position
2. DIP switch #3 on the Unit Number Control Board to the “ON” position
3. The hot water heater unit number can be selected by depressing SW2 on the Control Board.
The water heater unit number, which is displayed on the left two digits in the Control Board, will be flashing.
4. The Maintenance Mode can be selected by depressing SW3 on the Control Board. The water
heater unit number will change from blinking to steady ON.
38
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5. Select the type of maintenance by depressing SW2 (Group Number) and/or SW3 (Item
Number)
6. The initial maintenance item is displayed on the two right digits on the display unit flashing
between [Maintenance address – E1] and [Maintenance Data – the first error code].
7. If the number of combustion, combustion time is 0, then [- -] will be displayed on the two
right digits on the display unit.
8. When the water heater unit number “00” is assigned, the Control Board main body will
display the maintenance mode. The upper portion of the maintenance address can be selected with SW2, and the lower with SW3.
9. When the DIPSW 1 and 3 are switched to the “OFF” position, the Maintenance Information
Mode will end.
2nd Generation Flame Rod Chart
Flame rod chart is different for second generation 4.2 and 5.3 units. These units have two flame
rods; not three. The chart below shows the maintenance information at cell 0Y.
0y display 00 01 02 03
Flame Rod 1 X O X O Flame Rod 2 X X O O
X = Not detecting flame O = Is detecting flame
39
Page 41
Troubleshooting
• When measuring resistance of a part, turn off the electric power and be sure to
disconnect the part completely before measuring (from connector or terminal). Resistance checks are performed on the part while it is disconnected from the control board.
• Electrical checks are performed with the connectors in place and the unit turned on.
(Indoor Model Only) When performing maintenance and/or servicing the water heater without front cover, push the air filter switch down. Without pushing it down, Error Code [21] is displayed.
• All Molex connections only go to one location and fit one way. You do not need to
force a connection. Connections are also color coded to aid in reassembly.
• CAUTION When performing maintenance and/or servicing the water heater, turn off
the electric power, gas shutoff valve and water shutoff valve. Wait for the water heater to become cool. Be careful to avoid injury on th e sharp edges.
• WARNING Shock hazard - line voltage is present. Before servicing the water heater,
turn off the electric power to the water heater at the main disconnect or circuit breaker. Failure to do so could result in severe personal injury or death.
Troubleshooting Format and Example
Good. Proceed to your error code to resolve the issue. The error codes are listed in the table of contents.
This template is used
to troubleshoot error
codes to determine
faulty parts.
Are you familiar with
this format?
In some cases you will be asked to perform a test. That
Yes
test is contained in a box that looks like this.
No
If you are not familiar with this format, I will ask you a series of questions – one question at a time. You must perform the service check and work thru the tree based on the Yes or No result of the test.
Does this make sense to you?
You are welcome to call our technical service center at 1-800-432-8373. We will walk you thru your first error code. Please have a multimeter with you when you call. We will not be able to resolve the error codes on this machine without a multimeter capable of measuring AC voltage, DC voltage and OHMS resistance.
No Yes
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Page 42
Unit Will Not Power On
Explanation: Nothing happens when water is flowing through unit. At a minimum check the following in all cases:
1. Make sure unit is connected to proper 3 prong, grounded power supply and circuit
breakers are on.
2. Clean cold inlet water supply filter. Ensure you have at least the minimum flow rate
required to fire unit. Turn on several fixtures to make sure.
3. On new installations ensure hot and cold water lines are not crossed. Make sure the unit
is plumbed cold in to cold inlet. Unit will not fire off if water is running backwards.
Is the power
cord plugged
in? Is the
hardwiring
connected?
Yes
Is there
voltage at the
wall plug?
Yes
Will the unit
go into
Maintenance
Mode?
No
No
No
Yes
To access the Maintenance Display, turn the unit OFF. Then hold down the UP and DOWN arrow keys at the same time for a few seconds. You will hear an audible beep and see the display go to 0E. By pressing the UP and DOWN arrow keys on the remote display, you
Plug unit into a grounded, 3 prong wall plug. Verify hard wire to unit if applicable. Verify breaker at service panel is not tripped.
Check voltage at wall plug and circuit breaker for acceptable levels. Repair as required. This is not a water heater issue. This is an electrical issue.
Go to 1Y and verify zero flow rate. If there is ANY flow rate at 1Y; the unit will not power on.
41
Page 43
f
b
Yes
Is there
voltage thru
the 3 amp
fuses?
No
Check and verify the fused leads next to the junction box on the black and white wires are OK. Replace with 3 amp fuses if needed. Measure the voltage of the wires inside the junction box of the water heater between the black and white wires at 108 – 132 VAC
Is there power
to the Printed
Circuit Board
from the
transformer?
Yes
Is there power
to the Printed Circuit Board
thru the PCB
Yes
fuse?
No
Measure the voltage of the two red wires on the bottom right of the PCB @ 90 - 110 VAC. Second Generation 4.2, 5.3, and 7.4 series have black and white wires for this test. You will also see a true 120 volts. The second generation 4.2, 5.3and 7.4 series units don’t have trans
ormer.
No
Measure the voltage thru the fuse located on the board. Measure both sides of the fuse to ground @ 100 VAC. The second generation 4.2 and 5.3 units do not have a transformer; you will see 120 volts.
Unit appears to be OK. Try to restart.
See next page
Did the
unit go to
main urner?
Check fused power leads next to junction box.
Replace transformer
Replace 5 amp fuse
42
Page 44
b
b
b
g
Did the
unit go to
main urner?
No
Disconnect all remote controls from the PCB and attempt to restart the unit.
Yes
Unit appears to be OK.
Did the
unit go to
main urner?
The problem is with the remote control or the wiring to the remote control. Disconnect all additional wiring to the remote control and connect it directly to the Remote Terminal of the PCB.
Yes
Attempt to restart the unit.
Did the
unit go to
main urner?
No
OK - If you gone this far, there is one more thing to check. The pick-up sensor in the water flow control may be bad; or the board may be bad. Try this test:
Check connector S between the Red and Black. With the unit ON and no water flow, you should be 11-15 DC volts. If not, replace the PCB.
IF you have voltage, then.......
With the water flowing, measure 2-5 DC volts between the Brown and Black wire. (This is measuring water flow thru the control). IF you have a reading and no main burner, replace the PCB. If you do not have a reading, replace the water flow sensor.
Cold water inlet temperature may be to warm to restart the unit. While in
No
maintenance mode, go to 3y and determine the cold water inlet temperature. If the inlet cold water exceeds approximately 75 degrees, you may have a problem with the cold water being too warm for the machine to operate. Run the cold water for at least 3 minutes and recheck temperature.
Call technical service at 1-800-432-8373.
Replace Remote Control
Yes
Replace Remote Control wirin
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Error Code 00
Explanation: One Hour continuous combustion timer is activated. Unit has a 60 minute time that will shut off the main burner if used in excess of one hour. Cold water will continue to flow thru
the unit. (First generation products only – manufacture date thru Jul 06; models manufactured after August 2006 do not have a 60 minute timer.)
Unit will shut down automatically after 60 minutes of continuous use.
Turning off the hot water will reset the timer.
Turn off or remove circulation pumps. Unit is not designed for continuous operation with circulation systems.
Was the unit
used
continuously
for more than
one hour?
Yes
o
Unit appears to be OK. Try to restart.
No
“00” displayed?
Yes
Replace Circuit Board.
Is Error Code
Warning Code 05
Explanation: Imperfect Combustion Alarm is flashing. This monitor code explains the unit is having trouble maintaining a good combustion flame. The ODS sensor is activated and trying to resolve the fuel-air mixture issue. At a minimum check the following in all cases:
1. Clean air inlet filter.
2. Check for adequate combustion air ventilation openings.
3. Check and clean combustion air fan.
Is the Error
Code “05” flashing in the remote control
dis
Yes
No
Unit appears to be OK. Try to restart.
?
Unit is trying to resolve imperfect combustion. Increase fresh air to the unit. If the Rheem tankless cannot resolve the problem on its own, it will shut down with an error code of “13”.
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Warning Code 10
Explanation: This is a warning code. Fan Motor is not creating enough ventilation. The venting system passed pre-purge, but has failed during normal operation. At a minimum check the following:
1. Check for blockage of heat exchanger fins.
2. Check heat exchanger flapper valve at vent connection of water heater moves freely.
3. Clean air intake filter.
4. Remove all obstructions. Check the vent termination on the outside of the building and
the flapper valve at the top of the heat exchanger.
This warning code is followed by failure Error Code 99.
Error Code 11
Explanation: No ignition. This error code can be cause one three different scenarios. Please match the scenario to the fault condition before you troubleshoot. At a minimum check the following in all cases:
7. Ensure you have gas to the appliance.
8. Bleed all air from gas lines.
9. Ensure appliance is properly grounded.
10. Ensure gas line, meter, and regulator are sized properly.
11. Ensure gas type and gas pressure to the machine is correct.
12. Flex lines with a full 3/4 inch inside diameter may also restrict fuel flow enough to give
you error code 11. We do not condone the use of flex line gas piping with tankless.
Scenario 1 – Error Code 11; fan is operating; igniter does not spark.
Does the igniter
have voltage?
Yes
Is the igniter electrode clean? Is the electrode damaged? Is wirin
Yes
Replace Igniter Assembl
intact?
Remove the burner cover plate to inspect the igniter.
No
Replace Printed Circuit Board
Measure the voltage of connector H between both gray wires: 108 to 132 VAC.
You will need to cycle the unit to initiate an ignition attempt to conduct this test.
No
Clean/replace igniter electrode. Verify good ground.
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Scenario 2 – Error Code 11; fan is operating; igniter does spark; main burner does not ignite.
Does the Gas
Inlet Solenoid
Valve have a
voltage?
Yes
No
Replace Printed Circuit Board
Measure the voltage of connector K between Black and Yellow wires: 90 to 120 VDC
Does the
Solenoid Valve
#1 have a
voltage?
Yes
No
Replace Printed Circuit Board
Measure the voltage of connector K between Black and White wires: 90 to 120 VDC
Does the
Solenoid Valve
#2 have a
voltage?
Yes
No
Measure the voltage of connector K between Black and Red wires: 90 to 120 VDC
Replace Printed Circuit Board
Does the
Solenoid Valve
#3 have a
voltage?
Yes
No
Measure the voltage of connector K between Black and Blue wires: 90 to 120 VDC
The 2-4.2 and 5.3 units only have two stages of burner. Sk i p the next step.
Replace Printed Circuit Board
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y
y
y
Does the
P.G.F.R. valve
have a voltage?
No
Replace Printed Circuit Board
Yes
Measure the voltage of connector R between Black#2 and Red#1 wires:
1.5 to 14 VDC
Is the resistance
of the Gas Inlet Solenoid Valve
OK?
Yes
No
Replace Gas Control Ass
Measure the resistance of connector K between Black and Yellow wires:
0.8 to 2.4k Ohms
Is the resistance
of the Solenoid
Valve #1 OK?
No
Replace Gas Control Ass
Yes
Measure the resistance of connector K between Black and White wires:
0.8 to 2.4k Ohms
Is the resistance
of the Solenoid
Valve #2 OK?
No
Replace Gas Control Ass
Yes
Measure the resistance of connector K between Black and Red wires:
0.8 to 2.4k Ohms
Is the resistance
of the Solenoid
Valve #3 OK?
No
The 2-4.2 and 5.3 units only have two stages of burner. Sk i p the next step.
Replace Gas Control Ass
Yes
Measure the resistance of connector K between Black and Blue wires:
0.8 to 2.4k Ohms
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Is the resistance
of the
Proportional
Gas Control
Valve OK?
Yes
Check or replace main burner
No
Replace Gas Control Ass
Measure the resistance of connector R between Black#2 and Red#1 wires: 40 to 80 Ohms
Scenario 3 – Error Code 11; main burner ignites, but shuts off after ignition.
Display maintenance information 0
Try to ignite main burne
Does the 0y
display indicate
any remaining
flame?
No
Is there any
flame current?
No
Clean or replace main burner and Flame Rod Electrode
Yes
Refer to Error code 12 procedures
Yes
Replace Printed Circuit
Measure the electric current of Flame Rods connector M/L/T between wires and ground: 1 to 100 VA
Flame Rod Status: X=not detecting flame; O=is detecting flame
Flame Rod 1(white) X O X O X O X O Flame Rod 2(red) X X O O X X O O Flame Rod 3(blue) X X X X O O O O
Note: Notice the colors of the wires to the gas valve solenoids are the same color as the respective flame rods
to the right front half burner. Flame Rod 2 is the red wire and goes to the right rear half burner. Flame Rod 3 is the blue wire and goes to the left burner. (74 Series Only)
Normal flame rod status in the control panel with the burner on should be 01, 03 or 07.
If the burner has been removed for any reason AND any other flame rod status showing detecting flame (zero) probably indicates the flame rod wires are not correctl
0y display 00 01 02 03 04 05 06 07
. Flame Rod 1 is the white wire and goes
connected at the flame rod on the burner.
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Error Code 12
Explanation: Flame Failure. Unit went to main burner for a period of time; but has since lost flame or the ability to verify the presence of flame. At a minimum check the following in all cases:
1. Bleed all air from gas lines.
2. Ensure appliance is properly grounded.
3. Ensure gas line, meter, and regulator are sized properly.
4. Ensure gas type and gas pressure to the machine is correct.
5. Flex lines with a full 3/4 inch inside diameter may also restrict fuel flow enough to give
you error code 11.
For convenience, the RTG 66 model has a ¼ inch inlet gas pressure check port
on the gas connection nipple.
Unit appears to be OK. Try to restart.
Check and inspect burner assembly, flame rods, heat exchanger.
Does the unit
have proper
inlet gas
pressure?
Yes
Is the burner
manifold
pressure
normal?
Yes
No
Adjust inlet gas pressure based on fuel type.
Natural Gas: 4.0” to 10.5” w.c. LP Gas: 8.0” to 14.0” w.c.
Natural Gas Pressure
No
Adjust burner manifold pressure. See instructions on page 39.
L.P. Gas Pressure
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C
Error Code 13
Explanation: Oxygen Depletion Sensor activated. The unit was not able to resolve an imperfect combustion issue. At a minimum check the following in all cases:
1. Check for lack of fresh combustion air such as in a tight closet.
2. Check maintenance history to see if this is the first incidence of failure with this code.
If you get error code 13 and you can not seem to locate the problem, then try this to check for a potential missing sensor damper:
1. Check the wire from the ODS to PCB. A disconnected or loose wire will also show Ø
2. Recycle unit to main burner.
3. Run the unit for at least 3 minutes in main burner mode
4. Did the unit:
5. If so:
Is the ODS
thermocouple
OK?
Measure the voltage of connector Q between Red
Yes
The water heater seems to be normal. Try to operate again.
and White wires: 8 to 30 m VD
No
Is the burner
manifold
pressure normal?
Yes
No
Check the following: * Dirt or blockage of the heat exchanger or venting. Clean if necessary. * Check for dirt or blockage of the fan motor or air intake on the front cover. Clean if necessary. * Check for blockage of the flame opening of the sensing burner. Clean the entire burner assy. including sensing burner. * Disconnect the thermocouple and connector. Replace the upper burner ass
. Re-attach the connector firmly.
Confirm and adjust burner manifold pressure. See instructions on page 39.
(zero) voltage in maintenance mode.
a. Shut down at exactly 2.5 minutes? b. Never go to EC '05' to try and fix the problem? (ODS generated too low voltage
against minimum required voltage from ODS. The board never "senses" it is in an ODS failure and never tries to correct itself with the '05' code.)
a. Recycle power and go to maintenance mode. b. Go to cell ØA. c. Verify Ø voltage present (that is the correct reading) when main burner is off. d. Press the ON/OFF button to go to main burner. Turn on a water faucet. e. Run the unit for at least 3 minutes and watch the display cell ØA. f. If you get between8 mv and 30 mv, then the ODS and burner are probably OK.
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g. If within 3 minutes, you get any reading, and then the reading drops below 8 mv,
and then goes to Ø, then we have a problem with the ODS, a missing sensor damper or the burner itself. Replace the burner assembly.
What is the big different between normal error code 13 and no SD (Sensor Damper)? Normally error code 13 is just low voltage or frequency; it means the ODS is still sensing a burner flame. But if the SD is missing, there is no fire on ODS from the beginning of the main burner operation.
Does ODS still generate voltage because main burner ON? Yes, but the voltage is much lower than the PCB requires. You can verify this at cell ØA in maintenance mode.
Error Code 14
Explanation: Overheat Film Wrap has activated. There may be a hot spot on the heat exchanger that has caused the overheat film wrap to fault. At a minimum check the following:
1. Check gas type of unit and ensure it matches gas type being used.
2. Check heat exchanger for cracks and/or separations.
3. Check for restrictions in airflow around unit and vent terminal.
4. Check for a foreign materials in exhaust venting.
5. Before checking resistance of Molex connections, remove the Molex from the circuit
board.
Replace the PCB
Is the Molex
connector at
location U in
place?
Yes
Is the resistance
of connector U
OK?
Yes
o
Reconnectthe Molex and restart the unit.
No
Replace the uni
Measure the resistance of connector U between both white wires: 50k - 500 k ohms
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Error Code 15
Explanation: Boiling Safety Device. The heat exchanger is too hot. At a minimum check the following:
1. Check for restrictions in airflow around unit and vent terminal.
2. Check for a foreign materials in exhaust venting.
3. Back flush the unit to remote any sediment of buildup in the heat exchanger.
See section on how to display maintenance information.
Display maintenance information line [4y] Heat Exchanger Thermistor temperature. If 4Y displays 199°F – then physically check heat exchanger (Remote cannot display over 199°F.)
If actual temperature reaches 207°F for 15 seconds, Error code 15 displays. Unit will re-start at 194°F.
If actual temperature reaches 210°F for 1 second, unit shuts down. Unit will re-start at 194°F.
If actual temperature reaches 230°F, Error code 15 displays. Unit will not automatically restart.
The water heater appears to be normal. Attempt to operate again.
Does the
maintenance
information
indicate the heat
exchanger temp?
Yes
No
Is the resistance
to the heat exchanger
thermistor OK?
Yes
Replace Printer Circuit Board.
No
Measure the resistance of connector R between Black#3 and Yellow#5 wires: 4k - 10 k ohms
Replace Heat Exchanger Thermistor.
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y
Error Code 16
Explanation: Outlet water temperature is to hot. The outlet water temperature is above set point on the remote control. The unit cannot resolve the issue with the cold-water by-pass function.
Display maintenance information line [5y] Hot Water Outlet Thermistor temperature.
The water heater appears to be normal. Attempt to operate again. Check the water flow servo – especially the cold water bypass solenoid for operation. Check for blockage in the cold water
ass piping.
Does the
maintenance
information
indicate the hot
water outlet temp?
Yes
No
Is the resistance to the hot outlet thermistor OK?
Yes
No
Replace Hot Water Outlet Thermistor.
Measure the resistance of connector R between Black#3 and Red#4 wires: 4k - 10 k ohms
Replace Printed Circuit Board.
Error Code 21 (Indoor Models Only)
Explanation: Air intake filter switch does not work. The air intake filter switch ensures the front cover is attached and the inlet filter screen is in place and clean. Air intake switch and Error Code 21 has been removed from second generation 4.2, 5.3 and all Direct Vent (DV) models. At a minimum check the following:
1. Make sure air filter door is properly seated and clean.
2. Make sure front panel is properly installed with all four retaining screws.
3. Press the air intake switch when operating the unit without the front cover installed.
Is the Air Filter
Yes
Replace the Printed Circuit Board
switch OK?
No
Replace Air Filter Switch Ass
Press filter switch down. Measure the voltage and resistance of connector O between both white wires: Voltage = less than 1 VDC Resistance = 1 ohm
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Error Code 24
Explanation: Malfunction of Operational Switch. At a minimum check the following:
1. Disconnect remote control and retry.
2. Verify unit is electrically grounded. Do not use a 2 prong electrical adapter on the power
cord.
3. Press MAX (SW2) button on PCB to reset.
4. Press MIN (SW1) button on PCB to reset.
5. Check for presence of return circulation pump in the system.
Any water flowing thru the unit prior to turning unit ON may cause error code 24.
Does the unit
operate by
ushing either the
Min or Max
utton?
Caution: This is a diagnostic test. Do not operate the water heater for any length of time by pushing the SW1 or SW2 Button on PC Board. Do not open a hot water tap.
Yes
Unit appears to be OK. Reset unit and attempt to operate without pushing the Min/Max (SW1/SW2) Buttons.
No
Replace the Printed Circuit Board
Error Code 29
Explanation: Heat Exchanger outlet temperature is too low. At a minimum check the following:
1. Clean air inlet filter.
2. Check for buildup on the heat exchanger fins.
3. Set thermostat to 120 degrees. Verify heat exchanger temperature with water at hot
outlet.
Display maintenance information line [4y] Heat Exchanger Thermistor temperature.
Does the
maintenance
information
indicate the heat
exchanger temp?
Yes
The water heater appears to be normal. Attempt to operate again.
o
Is the resistance
to the heat exchanger
thermistor OK?
Measure the resistance of connector R between Black#3 and Yellow#5 wires:
Yes
Replace Printer Circuit Boar
4k - 10 k ohms
o
Replace Heat Exchanger Thermistor
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d
Error Code 31
Explanation: Water Inlet Thermistor has malfunctioned. At a minimum check the following if you get Error Codes 31, 32, 33, & 34:
1. Check for scale build up on the inlet filter screen. This scale build up could also happen
inside the machine. Scale build up on all thermistors will cause them to be inaccurate.
2. IF maintenance mode shows 32 degrees as the temperature, then the thermistor is not
making connection. (Possibly unplugged, possibly broken wire).
3. IF maintenance mode shows 199 degrees the thermistor has a direct short.
Display maintenance information line [3y] Water Inlet Thermistor temperature.
Does the
maintenance
information
indicate the cold
water inlet temp?
Yes
The water heater appears to be normal. Attempt to operate again.
Is the resistance
to the water
inlet thermistor
OK?
Measure the resistance of connector R
Yes
See Thermistor Resistance Chart for precise readings.
Replace Printer Circuit Boar
between Black#3 and White#6 wires:
0
F) - 19 k (380F) ohms
7k (79
No
Replace Water Inlet Thermistor
Error Code 32
Explanation: Heat Exchanger Thermistor has malfunctioned. At a minimum check the following:
Display maintenance information line [4y] Heat Exchanger Thermistor temperature.
Does the
maintenance
information
indicate the heat
exchanger temp?
Yes
The water heater appears to be normal. Attempt to operate again.
Is the resistance
to the heat
exchanger
thermistor OK?
Yes
Replace Printer Circuit Boar
No
Measure the resistance of connector R between Black#3 and Yellow#5 wires: 4k - 19 k ohms
55
Replace Heat Exchanger Thermistor
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d
Error Code 33
Explanation: Hot Water Outlet Thermistor has malfunctioned. At a minimum check the following if you get Error Codes 31, 32, 33, & 34:
1. Check for scale build up on the inlet filter screen. This scale build up could also happen
inside the machine. Scale build up on all thermistors will cause them to be inaccurate.
2. IF maintenance mode shows 32 degrees as the temperature, then the thermistor is not
making connection. (Possibly unplugged, possibly broken wire).
3. IF maintenance mode shows 199 degrees the thermistor has a direct short.
Does the
maintenance
information
indicate the hot
outlet temp?
Yes
The water heater appears to be normal. Attempt to operate again.
Display maintenance information line [5y] Water Inlet Thermistor temperature.
Is the resistance
to the hot outlet thermistor OK?
Measure the resistance of connector R between Black#3 and Red#4 wires:
Yes
Replace Printer Circuit Board
4k - 19 k ohms
No
Replace Hot Outlet Thermistor
Error Code 34
Explanation: Explanation: Ambient Combustion Air Thermistor has malfunctioned. At a minimum check the following:
Display maintenance information line [2y] Ambient Air Thermistor temperature.
Does the
maintenance
information
indicate the
ambient air temp?
Yes
The water heater appears to be normal. Attempt to operate again.
No
Is the resistance
to the ambient
air thermistor
OK?
Measure the resistance of connector R
Yes
Replace Printer Circuit Boar
between Black#3 and Blue#7 wires:
0
6k (93
No
F) - 19 k (380F) ohms
Replace Ambient Air Thermistor
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y
y
Error Code 35
Explanation: Improper Thermistor Connections. Check to make sure that all thermistor connections are good and in the proper locations. There are four thermistors on the tankless unit. They are the ambient air thermistor, cold water inlet, hot water outlet and heat exchanger thermistor. At a minimum check the following:
1. Check thermistor wiring and Molex connections.
2. Check and clean ambient air temperature thermistor.
3. There is no troubleshooting for this error code other than a visual inspection.
4. If a thermistor fails resistance check, then use that error code to process.
5. If all thermistors check good, then replace the board as first resolution.
Error Code 38
Explanation: Oxygen Depletion Sensor has malfunctioned. The sensor itself is not responding to the printed circuit board. At a minimum check the following:
1. Check sensor wiring and Molex connections at connector Q.
Replace Burner Assembl
Is there any
milivolt current
at Connector
Q?
Yes
No
Replace Printed Circuit Board
Light main burner and run for two minutes. Measure milivolt current at Connector Q between the Red and White wires: 8 to 30 mV DC
Error Code 51
Explanation: Gas Inlet Solenoid Valve fault. At a minimum check the following:
3. Check gas valve wiring harnesses for loose or damage terminals
4. Check connections to the circuit board are tight.
Cycle the heater two times by turning off – then on – at 10 second intervals.
Is there any
remaining
flame thru the
view window?
No
Display Maintenance Information 0y (flame rod status
Yes
Replace Gas Control Assembl
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Does the 0y
display indicate
any remaining
flame?
Yes
No
Flame Rod Status (Flame Rod #3 for 74 Series Only) 0y display Flame Rod 1 Flame Rod 2 Flame Rod 3 X=Not detecting flame O=is detecting flame
The water heater seems to be normal. Try to operate again
00 01 02 03 04 05 06 07
X O X O X O X O
X X O O X X O O
X X X X O O O O
Pull out the relay connection of flame rod connectors (M), (L), (T) and then display maintenance information [0y].
Does the 0y
display indicate
any remaining
flame?
No
Clean or replace Main Burner and Flame Rod Electrodes
Yes
Replace Printed Circuit Board
Error Code 52
Explanation: Proportional Gas Flow Regulator (P.G.F.R.) Valve fault. Check gas inlet solenoid valve wiring harnesses for loose or damage terminals; and connections to the circuit board are tight.
Yes
Replace P.G.R.F Valve
Is there power
to the P.G.R.F.
valve?
No
Replace the Printed Circuit Board
With the unit attempting to go to main burner, measure the voltage at connector R between the Red#1 and Black #2 wires for:
1.5 to 14 VDC
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(p
Error Code 61
Explanation: Combustion Fan failure. Fan motor does not work properly. At a minimum check the following:
5. Ensure fan motor will turn freely. Motor will operate with a small amount of restriction.
6. Check there is some volume of air from the flue outlet at the top of the heater.
7. Check wiring harness to motor for damaged and/or loose connections.
8. Check Molex connections of the PCB.
Does the Fan
operate?
Yes
The water heater appears to be normal. Attempt to operate again.
Replace Printed Circuit Board
No
Does the Fan
Yes
pulse output
from the Fan
Yes
Motor have
sufficient
voltage?
Is there any
Motor?
No
Replace Printed Circuit Board
Measure the voltage of connector G between Blue and White wires: 120 to 160 VDC If you accidentally cross the BLUE and WHITE wires with your multimeter leads, you will short out the circuit board and the
No
Replace Fan Assembl
Is there any pulse output from the Fan Motor? To measure the pulse output, turn on the fan by pushing "MAX" (SW2) Button. Measure the voltage of connector G between Blue and Yellow wires: 4 to 10 VDC
ulse)
Error Code 65
Explanation: Water Volume Control fault. At a minimum check the following:
4. Verify there is water flow thru the unit even if the unit does not fire.
5. Access maintenance information to determine flow rate.
6. Check all wiring connections to the water control and connector B on the Printed Circuit
Board.
Turn power off
and then on
again.
Is the voltage to
the water
control OK?
Yes
No
Replace the Printed Circuit Board
Measure the voltage at connector B between the Red#7 and Black#8 wires for: 8 to 16 VDC
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Yes
When motor
operates, is the
voltage to the
water control
OK?
No
Replace the Printed Circuit Board
Measure the voltage at connector B between the White#2 and Black#8 wires for: 8 to 16 VDC
Replace the Water Control Assembl
Error Code 66 (RTG66 Only)
Error Code 71
Explanation: Gas Inlet Solenoid Valve (G.I.S.V) fault. Check gas inlet solenoid valve wiring harnesses for loose or damage terminals; and connection K to the circuit board is tight.
Yes
Replace G.I.S.V. Valve
Is there power
to the G.I.S.V.
valve?
No
Replace the Printed Circuit Board
With the unit attempting to go to main burner, measure the voltage at connector K between the Yellow and Black wires for: 75 to 100 VDC
Error Code 72
Explanation: Flame Sensing Device fault. The Flame Probes are sensing the presence of flame when there is not suppose to be any flame.
See and follow the same procedure as used in Error Code 51.
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Error Code 76
Explanation: Communication Fault with Remote Control. At a minimum check the following:
1. Check remote control wiring for loose or damaged connections.
2. Bypass remote control cable by connecting remote control directly to remote control
terminals on PCB. Replace cable if found to be faulty.
Remove remote control wires from wiring terminal on the PCB. Plug unit in and open a hot water source.
to main burner?
Yes
Did the unit go
No
Replace the Printed Circuit Board
Either the wiring or the remote control is at fault. To rule out the wiring, disconnect the remote control and use a short, good jumper wire and connect directly to the remote terminal on the PCB. If the unit works using the remote, then the wiring is at fault. If the unit does not work, then the remote is at fault.
Error Code 79
Explanation: Fan Motor Current fault. Fan motor does not work properly. At a minimum check the following:
1. Ensure fan motor will turn freely. Motor will operate with a small amount of restriction.
2. Check fan motor for presence of moisture of condensation.
3. Check wiring harness to motor for damaged and/or loose connections.
See and follow the same procedure as used in Error Code 61.
Error Code 80/81
Explanation: Gas Cut-off Failure / Extinction Failure
See and follow the same procedure as used in Error Code 51.
Error Code 82
Explanation: Gas Type Control Data Failure; Printed Circuit Board data failure. The PCB has not been programmed, lost its programming or has failed. At a minimum check the following:
3. Check for the presence of the program chip installed on the PCB.
4. If the unit has operated for a period of time after installation, then the PCB was
programmed.
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play
p
5. If the unit does not operate on initial installation or after replacement of the PCB, then the
circuit board requires programming with the fuel type and altitude chip.
WARNING: When replacing High Altitude Connector, turn off the electric power to water heater.
Pull out the power cord to disconnect electricity. Reconnect power cord.
Was the proper
high altitude
fuel type
connector
installed?
No
Install or adjust the high altitude fuel type chip/dip switch settings
Yes
No
When the
ower turns on,
does the Error
Code 82 still
dis
?
Yes
The water heater seems to be normal. Try to operate again.
Replace the Printed Circuit Board and program chi
Install & adjust the proper Program chip according to the instruction. A different Program chip is required for every 3,280 feet. The Program chip is not interchangeable between Indoor and Outdoor models or type of gas. Check the number on the High Altitude Connector.
Error Code 90
Explanation: Blocked Flue. The venting system has failed the pre-purge test. At a minimum check the following:
1. Ensure maximum vertical vent length and elbows do not exceed allowable limits.
2. Ensure maximum horizontal vent length and elbows do not exceed allowable limits.
3. Check heat exchanger flapper valve at vent connection of water heater moves freely.
4. Is the entire vent structure clear and clean of any obstructions?
5. Remove all obstructions. Check the vent termination on the outside of the building and
the flapper valve at the top of the heat exchanger
6. You may rule out the venting by temporarily disconnecting the vent structure from the
water heater. If this fixes the problem, then the issue lies in the venting. If this does not
fix the problem, then the issue lies in the blower motor or printed circuit board.
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Error Code 99
Explanation: Fan Motor is not creating enough ventilation. The venting system passed pre-purge, but has failed during normal operation. At a minimum check the following:
1. Check for blockage of heat exchanger fins
2. Check heat exchanger flapper valve at vent connection of water heater moves freely.
3. Clean air intake filter.
4. Remove all obstructions. Check the vent termination on the outside of the building and
the flapper valve at the top of the heat exchanger
5. You may rule out the venting portion by temporarily disconnecting the vent structure
from the water heater. If this fixes the problem, then the issue lies in the venting. If this
does not fix the problem, then the issue lies in the blower motor or printed circuit board.
Warning Code IL
Explanation: Unit may have lime build-up inside heat exchanger. Drain and flush unit as follows:
1. Turn off the power and remote controller(s) to the water heater.
2. Turn off the gas and water shutoff valves.
3. Disconnect the unions above the shutoff valves. (This is not required if an “ISOLATOR
VALVE” is used in the water piping. See instructions provided with “ISOLATOR
VALVE” for further instructions.)
4. Connect temporary fittings with ½” barb fittings on one side and union on other side to
the inlet and outlet water connections.
5. Connect the pump hose outlet hose to the ½” barb fitting at the cold-water inlet fitting.
6. Connect the drain hose to the ½” barb fitting at the hot-water outlet fitting.
7. Pour approximately 5 gallons of virgin food grade white vinegar into a pail.
8. Place the pump or the inlet hose and the drain hose into the pail. A pond pump or similar
model can be used for this application.
9. Turn on the pump and allow solution to circulate for 45 minutes.
10. Turn off the pump and drain the vinegar from the pail. Fill pail with fresh water.
11. Turn on the pump and allow the water to circulate for 15 minutes.
12. Ensure full flow of water through the water heater.
13. Turn off the pump and drain the water from the pail.
14. Repeat steps 10 thru 15 if required to ensure full flow of water through heater
15. Remove the hose from the hose and adaptor fittings from the inlet and outlet connections.
16. Connect the unions back to the water heater fittings.
17. Remove water filter in inlet of water heater and remove any sediment or dirt.
18. Return filter to water heater and screw in filter.
19. Turn on the water shutoff valves and check for leaks.
20. Turn on gas shutoff valves, power and remote control.
21. Check and ensure safe operation and performance of the water heater.
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Warning Code P1
Explanation: Water flow rate is less than minimum for main burner ignition. The unit must have .66 gallons per minute before the main burner will light or sustain burner. When water flow does not reach minimum flow rate for five seconds the warning code is displayed. This warning code was introduced in September of 2007. At a minimum check the following:
1. Check cold water inlet screen for debris.
2. Check aerator screens of fixture for debris.
Disassembly and Repair – 1st Generation 7.4 product series
(1) When performing maintenance and/or servicing the water heater, always turn off the
electric power, gas shutoff valve and water shutoff valve. Wait for the water heater to become cool. Be careful to avoid injury to your fingers on sharp edges.
(2) Drain all water from the water heater when removing the water parts. (3) Before any disassembly, make sure you have a good diagnosis. Remove only the parts
needed.
(4) Handle all parts carefully. (5) When reassembling, prevent any foreign substance, i.e. dust, etc. from being introduced
into the water heater.
(6) After reassembling, check for gas and water leakage. Then, test ignition. Make sure
that there is no gas leakage in connections by testing with soap bubble solution. Bubbles indicate a gas leak that must be corrected.
(7) Check the performance and operation after servicing.
To remove and replace any part on this tankless unit, you will need a magnetic tip, #2 Phillips magnetic screwdriver that is at least 8 inches long. A flashlight and magnetic tip reach are also handy. Rheem recommends the use of a parts tray or bowl to hold small parts and screws. All of the hardware is essential to the proper operation of the unit upon re-assembly.
Process Illustration
1.
Printed Circuit Board (PCB)
a. Unscrew single screw at the
top of the PCB.
b. Pull PCB up and away. c. Remove all Molex
connections, Remote Control connections and transformer connections if replacing the board. Otherwise, leave the connections alone.
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2.
3.
Air Filter Switch
a. Remove the single screw closest to
white Molex connector.
b. Remove Molex if replacing air filter
switch.
Water Inlet Solenoid; Cold Water
Connection; Cold Water Inlet Thermistor
d. Step 1 and e. Remove four screws on the
cold water inlet connector (outside bottom of unit).
f. Note the connector has a
rubber o-ring and metal gasket to seal the connection.
g. Remove two spring clips on
cold water bypass pipes.
h. Remove three freeze
protection plugs.
i. Remove cold water inlet
thermistor.
j. Remove water flow sensor. k. Disconnect the solenoid
motor Molex.
l. Remove Water Control
Solenoid.
m. Note the water bypass pipes
have rubber o-rings to seal the connection.
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4.
5
Hot Water Outlet Connector and
Thermistor
a. Step 1 and 3 plus b. Remove electrical connection box
(single screw on outside left).
c. Remove one ceramic heater plug. d. Remove outlet pipe bracket and
ceramic heater plug.
e. Remove three screws on hot water
outlet connector (outside bottom of unit).
f. Gently pull outlet pipe from
connector and move to one side.
g. Unscrew and remove drain valve. h. Rotate and remove hot water outlet
thermistor from the unit.
i. Remove outlet connector and
retaining plate.
Transformer
a. Step 1, 3, 4 and b. Remove the two screws holding the
transformer to the back wall of the unit.
c. Disconnect power lead Molex on
transformer.
d. Disconnect red power leads on
Printed Circuit Board.
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5
Fan Assembly
a. Step 1 and b. Clip plastic tie holding Ambient Air
Thermistor.
c. Disconnect Fan Assembly Molex. d. Loosen wire clip holding the wire
bunch in place.
e. Remove three screws (one outside
bottom; one inside back left; one inside back right).
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6
Proportional Gas Flow Regulator
(Gas Valve)
a. Step1 and b. At the gas valve, remove the three
retains clips and screws from each of the gas manifold tubes. Note the brass colored tube has a special clip; the silver colored tubes have a different clip.
c. On the burner plate cover, remove
the two retaining clips and crews from the manifold supply tubes.
d. Note that each manifold tube has a
rubber o-ring on each end to seal the tube.
e. Remove the three screws from the
gas valve connector (outside bottom).
f. Remove the Proportional Gas Flow
Regulator from the unit.
g. Disconnect all Molex connections.
Note the three connections on the top of the valve are color code Blue, White and Red. They MUST be re­installed in the same location.
h. The single black (-) and red (+)
connections on the bottom right side must be re-connected to proper polarity.
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7.
8.
Burner Plate Cover
a. On the burner plate cover, remove
the two retaining clips and crews from the manifold supply tubes.
b. At the gas valve, remove the three
retains clips and screws from each of the gas manifold tubes. Note the brass colored tube has a special clip; the silver colored tubes have a different clip.
c. Note that each manifold tube has a
rubber o-ring on each end to seal the tube.
d. Remove the two screws that hold
the igniter mounting plate.
e. Remove the remaining 16 screws on
the perimeter of the burner cover plate.
f. Remember to re-connect the green
and yellow striped ground wire when reassembling cover plate.
Burner Assembly
a. Step 7 and b. Remove the three screws on the
bottom back wall of the burner assembly.
c. Firmly pull on both sides of the
burner assembly to slide it out of the chassis.
d. Disconnect all igniter wires and
flame probe wires.
e. Note positioning of the four black
plugs. They are used to prevent the wires from being damaged by the sharp edges.
f. Disconnect ODS Molex on PCB.
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8
9
10.
Igniter and Igniter Probes
a. Step 7 and b. Remove the two screws that hold
the right hand ceramic igniter probe (black wire) on the burner chassis.
c. Remove the two screws that hold
the left hand ceramic igniter probe (black wire) on the burner chassis.
d. Remove the igniters. e. Remove the igniter wires from the
end of the ceramic probes.
f. Reseat black rubber plugs to prevent
wires from pinching on metal.
Flame Rod(s)
a. Step 7 and 8 and b. Remove the two screws that hold
the right hand flame rod (white wire) on the front of the burner chassis.
c. Remove the four screws that hold
the back side flame rods (Blue and red wire) on the burner chassis.
Heat Exchanger Thermistor
Rear shown here. Red flame rod is on the left; blue is on the right.
a. Remove the two screws that hold
the heat exchanger thermistor in place.
b. Remove the thermistor. Note there
is a rubber o-ring to seal the thermistor.
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Parts
Below are the most common replacement parts. For a complete list of all replacement parts, please see the most current parts catalog.
Part Description Picture Water Flow Inlet Valve Cold water inlet valve that
measures water temperature and detects flow in gallons per minute
Oxygen Depletion Sensing Device (indoor models only)
Safety device that detects improper combustion (fuel-air mixture) and attempts to fix it
Proportional Gas Flow Regulator Valve (P.G.R.F.)
Gas valve that modulates and only allows the amount of fuel needed to heat the water being used
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Flame Rods Safety device that detects
the presence of flame
Igniter Spark igniter that lights
the main burner
Thermistor(s) A thermistor is an
electronic thermostat. There are four of them: cold water inlet, hot water outlet, heat exchanger and ambient air. Shown is the cold water inlet thermistor.
Hot water Outlet Valve Valve that delivers the hot
water to the piping system and measure the hot water outlet temperature with the aid of a thermistor.
Gas Inlet Connection Connection port – separate
from the gas valve – to connect the incoming gas supply.
Shown with supplied shut off valve.
PCB (Printed Circuit Board) The control board that
processes all the inputs required to make the machine operate
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Remote Control Digital control panel that
allows user to adjust temperature, monitor status of the machine and review certain maintenance functions
Air Filter Assembly Inlet air filter (indoor
models only) that keeps out lint and dust from inside the machine
Fan Assembly Fan (blower motor) that
draws fresh air into the machine and mixes it with the fuel for burning in the combustion chamber
Burner Assembly Burner component that
ignites the fuel-air mixture and provides heat for the heat exchanger
Water Filter In-line filter on the cold
water inlet assembly that filters out trash and sediment
Program Chip Removable electronic chip
that programs the fuel type, altitude level and product type and model number
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Parts Exploded View for RTG2-42PV and RTG 53PV
Ref # Description 1 Control Board
Control Board Fuse (5A) Power Line Fuse (3A) Program Chip 2 Gas Valve 3 Burner Assembly Flame Rod Ignitor Electrode Flame Rod Wire 4 Ignitor Coil 5 Fan Assembly
*PV = Power Vent (not Direct Vent) ** N/S = Not Shown
6 Burner Manifold 7 Gas Inlet Connector 8 Water Control Valve Inlet Thermistor -White 9 Water Inlet Connector 3/4 10 Inlet Water Filter 11 Hot Outlet Connector Outlet Thermistor - Black Drain Relief Valve 13 Door Filter Screen N/S** Heat Exchanger Thermistor -Yellow N/S** Ambient Thermistor -Blue
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Parts Exploded View for RTG 53X
Ref # Description 1 Control Board
Control Board Fuse (5A) Power Line Fuse (3A) Program Chip 2 Gas Valve 3 Burner Assembly Flame Rod Flame Rod Wire Igniter Electrode 4 Ignitor Coil 5 Fan Assembly
* X = Outdoor Model ** N/S = Not Shown
6 Burner Manifold 7 Gas Inlet Connector 3/4 8 Water Control Valve Inlet Thermistor -White 9 Water Inlet Connector 3/4 10 Inlet Water Filter 11 Hot Outlet Connector 3/4 Outlet Thermistor - Black Drain Relief Valve N/S** Heat Exchanger Thermistor -Yellow N/S** Ambient Thermistor -Blue
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Parts Exploded View for RTG 53DV
Ref # Description 1 Control Board
Control Board Fuse (5A) Power Line Fuse (3A) Program Chip 2 Gas Valve 3 Burner Assembly Flame Rod Flame Rod Wire Igniter Electrode 4 Ignitor Coil 5 Fan Assembly
* DV = Indoor Direct Vent Model ** N/S = Not Shown
6 Burner Manifold 7 Gas Inlet Connector 3/4 8 Water Control Valve Inlet Thermistor -White 9 Water Inlet Connector 3/4 10 Inlet Water Filter 11 Hot Outlet Connector 3/4 Outlet Thermistor - Black Drain Relief Valve N/S** Heat Exchanger Thermistor -Yellow N/S** Ambient Thermistor -Blue
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Parts Exploded View for RTG 66DV
Ref #
Description
1 Control Board Control Board Fuse (5A) Power Line Fuse (3A) Heat Exchanger Thermistor - Yellow Ambient Thermistor - Blue 2 Inlet Thermistor - White 2 Outlet Thermistor - Black Gas Valve - LP 7 Gas Valve - NAT 3 Gas Control Resistor 6 Gas Inlet Connector 3/4 6 Burner Assembly Burner Manifold - LP Burner Manifold - NAT 4 Sensor Orfice - LP
4 Sensor Orifice - NAT Ignitor Coil 5 Ignitor Electrode Ignitor Electrode 8 Blower Motor 8a Blower Case 9 Water Control Valve 14 Water Bypass Valve Water Inlet Connector 3/4 Remote Control Terminal Block 10 Terminal Block Wire Assy 11 Screw Pan FT 4x12 Inlet Water Filter Hot Outlet Connector Door Screw Chassis Screw Mounting Brackets
Only fuel specific chips are required for replacement control boards. Altitude is controlled through dip switch settings and does not require a program chip. See Use and Care for details.
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Parts Exploded View for RTG 74PV and GT 199PV
Ref # Description N/S** Transformer (120v to 100v) 1st
Generation only 1 Control Board Control Board Fuse (5A) Power Line Fuse (3A) Program Chip 2 Gas Valve 3 Burner Assembly Ignitor Electrode Flame Rod Flame Rod Wire 4 Ignitor Coil 5 Fan Assembly 6 Burner Supply Tubes
* PV=Indoor Power Vent Model ** N/S = Not Shown
7 Gas Inlet Connector 3/4 8 Water Control Valve Inlet Thermistor -White 9 Water Inlet Connector 3/4 10 Inlet Water Filter 11 Hot Outlet Connector Outlet Thermistor -Black Drain Relief Valve 12 Door Switch 13 Door Filter Screen N/S** Heat Exchanger Thermistor -Yellow N/S** Ambient Thermistor -Blue
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Parts Exploded View for RTG 74DV and GT 199DV
Ref # Description N/S** Transformer (120v to 100v) 1st
Generation only 1 Control Board Control Board Fuse (5A) Power Line Fuse (3A) Program Chip 2 Gas Valve 3 Burner Assembly Ignitor Electrode Flame Rod Flame Rod Wire 4 Ignitor Coil 5 Fan Assembly 6 Burner Supply Tubes
* DV=Indoor Direct Vent Model ** N/S = Not Shown
7 Gas Inlet Connector 3/4 8 Water Control Valve Inlet Thermistor -White 9 Water Inlet Connector 3/4 10 Inlet Water Filter 11 Hot Outlet Connector Outlet Thermistor -Black Drain Relief Valve 12 Door Switch 13 Door Filter Screen N/S** Heat Exchanger Thermistor -Yellow N/S** Ambient Thermistor -Blue
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Parts Exploded View for RTG 74X and GT 199X
Ref # Description N/S** Transformer (120v to 100v) 1st
Generation only 1 Control Board Control Board Fuse (5A) Power Line Fuse (3A) Program Chip 2 Gas Valve 3 Burner Assembly Ignitor Electrode Flame Rod Flame Rod Wire 4 Ignitor Coil 5 Fan Assembly 6 Burner Supply Tubes
* X =Outdoor Model ** N/S = Not Shown
7 Gas Inlet Connector 3/4 8 Water Control Valve Inlet Thermistor -White 9 Water Inlet Connector 3/4 10 Inlet Water Filter 11 Hot Outlet Connector Outlet Thermistor -Black Drain Relief Valve 12 Door Switch 13 Door Filter Screen N/S** Heat Exchanger Thermistor -Yellow N/S** Ambient Thermistor -Blue
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Rheem® Water Heating
®
Ruud
Water Heating 1241 Carwood Court Montgomery, AL 36117
1-800-432-8373 www.rheemtankless.com
Printed in the U.S. 08/08 Form No. SVC810
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