KB Series
Condensing Water Heater
Service Fundamentals
Level III
KB Series Water Heaters
2
Model
Trade Name
Minimum Btu
Maximum Btu
REU-KB2530-FFUD-US
RU80i
15,200
152,200
REU-KB3237-FFUD-US
RU98i
15,200
199,000
REU-KB2530-WD-US
RU80e
15,200
152,200
REU-KB3237-WD-US
RU98e
15,200
199,000
Important Information
Installation - MUST be performed by a licensed contractor.
Gas System - MUST be properly sized for gas load at location. Refer to the
International Plumbing Code Book for proper sizing guidelines based on total gas load
at site.
Vent System - MUST use one of Rinnai’s listed and tested vent systems.
Electrical System - MUST be properly sized for load at location. Refer to the National
Electrical Codes for details. Each unit requires 120 Volts AC, 10 amp grounded circuit.
Water System – MUST be properly sized for total water flow at location. Refer to the
International Plumbing Code for details. Each unit has a ¾” feed line to the appliance. .
Circulation System – MUST be properly sized. Refer to pressure drop chart in owner’s
manual for each unit. Pressure drop in plumbing system MUST be taken into account. If
you have questions contact Rinnai engineering before installation.
3
Rinnai Service and Support (800-621-9419)
 CRC – Consumer Response Center – general calls, consumer questions, etc.
Available from 8 a.m. to 8 p.m. EST, Monday – Friday.
 Parts Department – parts orders.
Available from 8 a.m. to 8 p.m. EST, Monday – Friday.
 Warranty Department – warranty claim issues.
Available from 8 a.m. to 5 p.m. EST, Monday- Friday.
 Technical Support Department – technical issues related to the function and repair of all
Rinnai products.
Available in the office from 8 a.m. to 8 p.m. EST, Monday – Friday AND 24/7/365 on call support for
technicians who are at the service location. Technicians only, call 1-888-RINNAIS ( 888-746-6247)
 Engineering / Applications Department – calls related to product use and applications
including sizing.
Available from 8 a.m. to 5 p.m. EST, Monday - Friday.
Rinnai America also provides the following websites for support:
• www.rinnai.us –for installation manuals, product specifications and supporting documents. More technical information
is available in the “For Professionals” section of the site under “Partner Portal”. Registration is required for access to
this portion of the website.
• www.trainingevents.rinnai.us – for registration in Rinnai product training classes and videos (live and online classes).
Service and installation manuals and other technical documents are available under the “Resources” section of the site.
General
All components in the Rinnai tankless water heaters are field replaceable.
All major replacement parts are accompanied with replacement procedures.
Dip switches on PC board allow for proper altitude settings without having to derate the product through orificing and gas pressures. See data sheet under front
cover, setting dip switches will automatically de-rate the unit. No other adjustments
are required.
Please refer to each model’s data sheet and/or service documentation for specific
model information.
If you are unable to diagnose the product contact Rinnai Technical Support for
assistance.
Rinnai pays reasonable labor normally one hour for all parts, except heat
exchangers.
5
Primary Service Tools
For service, troubleshooting, and component replacement, the following tools are needed
#2 Phillips
Head
(magnetic)
and
Screw Drivers
6
Small
Phillips
Head
U-Tube
Manometer
or
Digital
Multimeter
(Volt/Ohm Meter)
Front Panel Removal
To remove front cover press in on the plastic
strip roughly 3” down from the top of the unit and
3” up from the bottom of the unit, at red circles
to right with your thumbs.
Pull out on the plastic strip removing it from the
unit. .
Under the plastic strip you will find four Phillips
head screws securing the front cover, remove
those and pull the front cover off the unit.
Screw under plastic strip
7
Front Panel Information
Under the front panel of the unit you will find a wiring
diagram and technical data sheet. The technical data
sheet contains a parts diagram with part numbers and
various service information including:
• Error code information
Technical data sheet
• DIP Switch/Gas Pressure settings
• Electrical Component Values
• Venting information
• Temperature controller information
8
Wiring diagram
1. Internal unit, slide control up and pull from bracket. This is an integrated controller
that has a dedicated 15 wire connector on the PC board.
2. All additional controllers for the internal and/or external units connect to the
“terminals for controls” on the PC board. See item 2 below for location of these
terminals. DO NOT connect your power supply (120 volts AC) to these terminals.
3. To remove controller bracket, remove (2) screws from the bracket, shown below. .
.
Internal
3
2
9
Manifold and Sight Glass Plate
Ensure unit is isolated from power and gas supply
1. Gas Solenoid Valves
2. Burner/gas manifold
1
3. Flame rod (yellow wire)
4. Burner or TC sensor
(red & white wire)
5. Igniter (black wire)
6. Sight glass.
2
3
10
4
5
6
Sparker Electrode & Flame Rods Removal
Ensure unit is isolated from power and gas supply.
1. Unplug igniter (black wire).
2. Unplug burner sensor (red & white wire)
3. Unplug flame rod (yellow wire).
4. To remove the igniter, flame rod and burner sensor, remove sight glass plate, total of six screws
at red circles. You MUST replace the sight glass plate gasket if this plate is removed. .
3
11
2
1
Burner Manifold Removal
Ensure unit is isolated from power and gas supply..
1. Unplug igniter (black wire) see previous slide.
2. Unplug burner sensor (red & white wire) see previous slide
3. Unplug flame rod (yellow wire). see previous slide
4. To remove the burner manifold remove the ten screws shown with red circles. You MUST
inspect and replace burner manifold gasket if this plate is removed. .
5. Unplug SV1 (Black & Blue wire)
6. Unplug SV2 (Black & Yellow wire)
7. Unplug SV3 (Black & Red wire)
8. Remove one screw from gas
feed line at red arrow, slide
locking clip off housing and pull
manifold from unit.
Reassemble in reverse order. . .
12
SV2
SV1
SV3
Gas
feed
Burner Manifold Layout
The top section is the back side of the burner manifold, bottom portion of picture is showing the
burner manifold chamber. .
SV1 controls (4) burners (Black & Blue wire)
SV2 controls (4) burners (Black & Yellow wire)
SV3 controls (10) burners (Black & Red wire)
SV2
13
SV1
SV3
Heat Exchanger Thermistor Removal
Ensure unit is isolated from water & power. Open a fixture to
release water pressure in system.
1. Remove the heat exchanger thermistor by pulling retainer
clip off thermistor. Pull thermistor out of position. Ensure Oring is intact and in good condition before reinstalling it.
2. Follow thermistor wire back to a Molex connector. Unplug at
that point and remove it from unit.
1
Remove retainer clip
Thermistor location
14
Outgoing Water Thermistor Removal
Ensure unit is isolated from water & power. Open a
fixture to release water pressure in system.
1. Remove the outgoing water thermistor by removing
one screw that is holding it in place. Pull thermistor
out of position. Ensure O-ring is intact and in good
condition before reinstalling it. .
2. Follow thermistor wire back to a Molex connector.
Unplug at that point and remove it from unit.
Remove screw
Wipe up water
spillage to prevent
leak detector from
setting off code 79.
15
1
Thermistor location
Inlet Thermistor Removal
Ensure unit is isolated from water & power. Open fixture to release water pressure
in system.
1. Remove the inlet water thermistor by pulling retainer clip off the thermistor. Pull
thermistor out of position. Ensure O-ring is intact and in good condition before
reinstalling it.
2. Follow thermistor wire back to a Molex
connector. Unplug at that point and remove
it from unit.
Remove retainer clip.
Wipe up water
spillage to prevent
leak detector from
setting off code 79.
16
1
Thermistor location
Bi-metal Over Heat Switch #1
The overheat bi-metal circuit activates based on the temperature range listed
below. Bi-metal switches automatically reset once the temperature drops below
the activation point.
1. Overheat switch #1 - located on the right side of the primary heat exchanger. Activation
temperature is 206˚F (97˚C).
Bi-metal switch #1 right side of HEX
Bi-metal switch #1
1
17
1
Bi-metal Over Heat Switch #2
The overheat bi-metal circuit activates based on the temperature range listed
below. Bi-metal switches automatically reset once the temperature drops below
the activation point.
1. Overheat switch #2 – Located on burner assembly, there are two of these both on the
back side of the heat exchanger, one on the right top of the burner and one on the left top
side of burner. Activation temperature is 302˚F (150˚C).
Bi-metals located on top of burner
Top of burner assembly
1
1
18
Bi-metal Over Heat Switch #3
The overheat bi-metal circuit activates based on the temperature range listed
below. Bi-metal switches automatically reset once the temperature drops below
the activation point.
1. Overheat switch #3 - , Located on rear of unit at air box connection and heat exchanger
assembly. There are two of these one on each side of the air box. Activation temperature
is 212˚F (100˚C).
Air box chamber back
side of heat exchanger
Close up of bi-metal switches
1
1
19
Thermo Fuse
1. The thermal fuse circuit activates at 430˚F (221˚C).
Thermal fuses are a “one shot” device, MUST be
replaced if activated. The thermal fuses wrap
around the heat exchanger, see item #1 at right.
2. To replace the thermal fuse the heat exchanger has
to be removed. Ensure no wires are pinched upon
re-assembly. Tip: Pinched or grounded wires will
cause an immediate error code 19.
3. To unplug the thermal fuse harness, locate a single
white wire and a white and red wire at their Molex
connectors, see locations and item #2 to at right. .
2
An open bimetal or thermal fuse is usually a symptom of an underlying issue (i.e. scale build up, fin blockage
inside the heat exchanger, improper gas conversion, improper gas pressure , wrong gas type). The cause of
20
this symptom must be determined in order to prevent ongoing product issues.
Overheat Safety Protection
The Rinnai Safety “Line of Defense”
Multiple layers of technology ensure safe operation
21
If the heat exchanger
thermistor detects
unusually slow heat
dissipation after the
flame stops…
If the outlet
thermistor detects
6-8°F over the
temperature set
point…
An LC warning
code will post on
the temperature
controller (unit
will continue to
operate)
The flame will
turn off until the
temperature
decreases (no
code is posted)
If the overheat
bimetals detect
206˚F, 212˚F or
302˚F based on
which bimetal
activates…
The safety
circuit is broken
and a code 14,
57 or 58 will
post on the
controller
If the heat exchanger
thermistor detects a
boiling condition
206˚F…
If the thermal
fuse detects
430˚F…
The flame will
turn off until the
temperature
decreases (no
code is posted)
The safety
circuit is broken
and a code 14
will post on the
controller
Combustion Fan
Ensure unit is isolated from power.
1. Remove the two fan housing screws.
2. Unplug Molex connector for fan motor.
3. Remove screw and pull air tube loose..
1
2
4. Slide fan motor out of unit. .
3
22
Burner & Heat Exchanger Removal
Turn off power supply, water and gas to product. Then disconnect the following
wiring harnesses to begin removing burner and heat exchanger assembly.
5
1.
2.
3.
4.
5.
6.
7.
8.
9.
Unplug heat exchanger thermistor connector.
Unplug ceramic heaters (green & white connectors).
Unplug bi-metal switch connector (red wires).
Unplug SV1, SV2, and SV3 solenoids
Unplug burner sensor connector.
Unplug freeze protection thermistor, external unit.
Unplug combustion motor .
Unplug igniter connector.
Unplug Thermal fuse connectors, upper plug has red
and white wires, lower single white wire.
10. Unplug inlet water thermistor
6
4
7
8
9
1
2
3
23
10
Burner & Heat Exchanger Removal
Next, ensure the water supply is turned off and pressure bled from system
1.
2.
3.
4.
5.
6.
Remove screw from outlet water connection and pull water line out of fitting.
Remove screw from inlet water connection and pull water line out of fitting.
Remove screw from bypass assembly connection and pull water line out of fitting.
Compress clamp and slide rubber hose off connection.
Remove (2) screws from gas valve connection and pull gas line from fitting.
Remove black nipple, then (2) screws from bottom of unit holding copper drain tube.
4
6
5
2
1
3
24
Burner & Heat Exchanger Removal
Disconnect vent system from top of unit.
1. Remove the (6) screws shown inside red circles at the top of the heat exchanger. .
2. Remove (4) additional screws at the bottom of the heat exchanger shown in red circles.
3. Remove the (4) screws holding the vent connection to the top of the water heater. Pull vent
connection off unit. Now lift heat exchanger assembly out of unit.
1
2
25
Burner & Heat Exchanger Removal
Air box from rear of heat exchanger.
1. Remove (9) screws as shown below.
.
1
26
Burner & Heat Exchanger Removal
Burner assembly
1. Remove (15) screws as shown below in red circles
2. Pull burner assembly away from heat exchanger
3. Reassemble in reverse order,
replace gasket between
burner and primary heat
exchanger
1
27
Burner & Heat Exchanger Layout
Burner, flame rod, igniter and burner sensor
1. Ceramic burners from combustion chamber side.
Burner Sensor
Flame rod
SV2
28
Igniter
SV1
1
SV3
Burner Sensor
The burner sensor can be checked with a volt/ohm meter, see
example to right, short and open circuits.
Short circuit read resistance
Between sheath and cable
(whichever) will be zero.
The burner sensor measures flame intensity in all 7 stages
of combustion. .
If the burner sensor does not detect a temperature
between 400 ˚F and 1,400 ˚F it will shut down flashing a
code 73.
If a code 73 occurs verify low/high fire gas pressures and
dip switch sittings for your altitude. In addition, check for
blockage in the air passageways and venting. Inspect fan
assembly, burner and heat exchanger fins for blockage as
well.
Open circuit measure between
each wire looking for infinite ∞
Next, verify low/high fire gas pressures and dip switches
are set for the proper altitude.
The burner sensor
29
Secondary Heat Exchanger Removal
Secondary heat exchanger assembly
1. Remove (14) screws as shown below in red circles
2. Pull secondary heat exchanger away from primary heat exchanger.
3. Reassemble in reverse order, replace gasket between secondary and primary heat
exchangers.
30
Gas Valve Assembly Removal
CAUTION; before proceeding turn off power and gas supply to unit.
1.
Remove 2 screws from gas line leaving valve, this line feeds gas to the manifold assembly. Rotate
retainer to release aluminum gas line. Pull aluminum line away from gas valve. Ensure O-ring stays intact.
2.
Unplug POV solenoid wiring harness, yellow/yellow wires on rear of gas valve.
3.
Unplug SV0 main solenoid harness, pink/black wire on front of gas valve.
4.
Remove 3 screws from bottom of unit that hold gas valve and inlet
connection in place.
1
3
2
4
31
Water Outlet Fixture & Thermistor
1. Ensure unit is isolated from water & power.
2. Remove screw from heat exchanger outlet retainer. Rotate retainer to release. Pull copper
heat exchanger outlet away from fixture. Ensure o-ring stays intact. Remove ceramic antifrost heater from fixture.
3. Remove pan-head screw holding outlet thermistor.
4. Ensure thermistor o-ring is intact and on thermistor upon reinstall. Ensure thermistor is
clean.
Heat exchanger outlet cavity
Ceramic heater cavity
Outlet twin thermistor cavity
(with O-ring)
2
3
32
Water Flow Servo Valve Removal
Ensure unit is isolated from water & power.
1.
Bleed water pressure at a fixture. Next; remove 2 screws from Water Flow Servo Valve (WFSV) outlets.
Rotate retainers to release copper lines. Pull copper lines away from WFSV. Ensure O-rings stays intact.
2. Unplug by-pass flow control valve, blue, red, pink and white wires at light blue connector.
3. Unplug WFSV feedback module and motor, the feedback module has blue, pink, red and white wires, the
WFSV motor has grey, orange and brown wires at the white eight pin connector.
4. Unplug WFSV sensor, red, black and yellow wire at red connector.
5. Unplug ceramic anti-frost heater, two white wires at green connector.
4
2
5
1
3
33
Water Flow Control Valve Removal
continue
6. Remove 3 screws shown from bottom of unit’s inlet water connection. Pull down on inlet connection
ensuring O-ring is intact and in good condition. Now you should be able to remove the water flow control
valve from unit.
7. Reassemble in reverser order.
6
34
Water Flow Control/Bypass Valve
1. To separate water flow control valve (WFCV) from bypass valve, remove 2 screws shown
below. Upon reinstall ensure O-ring is intact and bypass valve orientation is correct.
2. To remove turbine from assembly, remove the plastic retainer ring. CAUTION: Turbine is
fragile. To disassemble turbine remove top cap. Impeller will come free of housing. Reinstall
with notch in plastic housing in grooved out slot in WFSV assembly.
3. Water flow control valve assembly with turbine in place.
Bypass Valve Assembly
Turbine Assembly
WFCV – bottom view.
1
2
35
WFCV Assembly
3
Water Flow Control Troubleshooting
TROUBLESHOOTING TIP
A clicking sound from inside the water heater accompanied by a temperature controller with no display or
sporadic flashing temperature (not an error code) on the display is indicative of a water flow control issue.
To troubleshoot:
• Unplug the water flow control wiring harness - this harness has a brown, grey and orange wire.
• If the clicking noise stops and the temperature controller returns to a steady temperature display, the water
flow control valve may need to be replaced - contact Rinnai technical support at 1-888-746-6247 with the
full model (REU-KBXXXXXX) and serial number.
Unplug this harness
to troubleshoot water
flow control
assembly
36
PC Board Removal
1. Disconnect the power from the unit.
2. Remove the two screws at the top and bottom of PC Board casing.
3. Pull the PC Board up, in the raised position disconnect all connections. Take care not to stress
the connections when unplugging them. Press in on the latch to release the connector before
unplugging connection. You can use a small screw driver to push in on these latches.
All connections are uniquely keyed to
their individual plug on the PC
board..
If the PC board is replaced, Dip
switches and gas pressure must be
reset/verified. SW1 set of dip
switches have tan tabs, SW2 white.. .
37
Accessory Wiring
Note: harnesses for future accessory use:
1.
EZConnect: connects two tankless products in a manifold
2.
MS: Connects up to twenty-five tankless units in a manifold system
3.
BMS or Air-H: Air Handler Control Switch or Building Management System interface
4.
Anti-Freeze: For freeze protection solenoid package.
5.
Cir-Logic: Connects and controls a circulation pump in residential applications (2) amp pump maximum.
5
4
2
3
1
38
Product Reassembly
Re-assemble in opposite order of disassembly
All screws should be placed in the correct location.
DO NOT over tighten screws
All wiring harness connections must be plugged up to correct
connector, solenoid valves, etc.)
Note: Do not apply power until the product is inspected by the
instructor!
39
Electrical Requirements
and
Troubleshooting
40
Electrical Diagnostic Points
Verifying electrical values of individual components is not common but when necessary, must be conducted
correctly and safely. Verifying incoming supply voltage is the most common metering needed in the field—
especially during installation.
Key points when troubleshooting electrical values:
1. Ensure volt meter probes are solidly contacting metal
2. Apply probes to the back of Molex connections where wires enter Molex connector to prevent possible
damage to plugs.
3. Know your meter and how to set it for each type of measurement. Always set meter to next highest value f
from range listed in troubleshooting sheets.
Ω = Ohms or resistance
K = X1000/ ex. 6K Ω = 6000 Ohms
VAC or V~ = AC voltage
VDC or V- = DC voltage
4. When measuring resistance, ensure the component is disconnected from the circuit AND power is
removed.
5. When measuring a solenoid’s resistance, place the meter probes on the solenoid’s lugs (connection points)
with the wires disconnected from solenoid.
6. A correct resistance reading from a solenoid or transformer coil is not a guarantee that the component is
good as the windings can open under load. An incorrect value is a very good indication that the component
is bad though.
41
Electrical Diagnostic Points
1.
Measure incoming voltage at receptacle, should be 120 volts AC.
2.
Check at connector “F” on PC board across black
wire pin #3 and white wire pin #1.
3.
Verify fuse is not blown.
4. Measure continuity of safety circuit starting at
connector “B” pin #1 white wire & connector “G” pin
#8 red wire.
5.
6.
E
Measure resistance of gas solenoids valve SV1 on connector
“B” black wire pin #4 and blue wire pin #6. Resistance
reading should be between 35 ~ 41 ohms.
D
Measure resistance of the modulating solenoid valve
(POV) on connector “D” across yellow wires on pins #1
and 2. Should have between 67 ~ 81 ohms.
G
B
7. Measure resistance of outgoing water thermistor on connector
“E” across white wires on pins #2 and 3.
59 ˚F
86 ˚F
113 ˚F
140˚F
221 ˚F
42
=
=
=
=
=
11,4 ~ 14K ohms
6.4 ~ 7.8K ohms
3.6 ~ 4.5K ohms
2.2 ~ 2.7K ohms
0.6 ~ 0.8K ohms.
F
Electrical Diagram
43
Temperature Controllers
MC-91
MCC-91*
*for commercial / space heating use only
MC-100
BC-100
You can use up to four controllers installed in parallel in any combination, (exception: only
one MC-100 and one BC-100 per unit)
44
Temperature Range
Code restricts maximum set temperature to 120˚F (49˚C) out of the box. Enhances safety
of users, especially children and the elderly.
Temperatures between 125˚F - 140˚F (52˚ - 60˚C) are available by setting dip
switch #6 to the “ON” position in the SW1 bank of dip switches. If switch #6 is
changed to achieve the temperatures mentioned above this will effect the
minimum flow rate activation requiring 1 gpm to fire the unit. This can be over
come by flipping dip switch #7 to “ON” in the SW1 bank of switches. That will
allow 0.4 gpm to activate the unit.
If using the EZConnect cable or the MSB control with a
bank of units, the above procedure does not apply. When
using these components at higher output temperatures
the minimum flow rate maintains 0.4 gpm without having
to change dip switch #7.
Temperatures above 140 ˚F are available for commercial
applications using the MCC-91-2 controller. See owner’s
manual for details.
45
→ ON
O
F
F
1
2
3
4
5
6
7
8
S
w
i
t
c
h
N
u
m
b
e
r
Temperature Controllers
- Remote controller wires are connected on the unit PC board see
terminals to right inside red circle. “Wires are not polarity sensitive.
- Internal units come with a temperature controller integrated into the
front cover and its wiring is already connected.
- External units come with an independent temperature controller to
be installed remotely.
- Controllers operate on 12 VDC digital provided at terminals for
controls to the right.
- Standard thermostat wire can be used to connect the controller to
the water heater.
:
46
MC-91-2US Controller Functions
To change from ˚F to ˚C or ˚C to ˚F press and hold the
down for 5 seconds with the unit in the off position.
MC-91-2US
To lock the controller on a set temperature press and hold the Priority
and .
simultaneously for 5 seconds a beep will sound. Display
will
alternate between “LOC” and the set temperature.
To mute the audible beep press and hold the
and
an audible beep is heard approximately 5 seconds.
MC91-2US controller provides additional diagnostics. To display previous error codes press
down for 2 seconds, then simultaneously press the
then release both bottoms...
To enter or exit the error code monitor information press and hold the
press the
then release both buttons.
To display various diagnostic information press the up or
down arrows. Ex: “01” which will then display water flow
rate or “02” which will then display outgoing water
temperature.
47
button
until
, hold
for 2 seconds, then simultaneously
Controller Maintenance Monitor
To enter or exit the maintenance monitor information mode
press and hold
for 2 seconds and simultaneously press
To display various diagnostic information press the up or down arrows. Ex: “01” which will then display water flow rate
or “02” which will then display outgoing water temperature
.
CODE
O1
O2
O3
O4
O5
O6
O7
O8
O9
10
11
12
13
14
15
16
17
18
O7*
CONTENTS
Water Flow GPM
Outlet Temp.
Hrs. Operation
Combustion Freq.
Fan Frequency
System
Water Flow Servo Position *
Inlet Water Temp.
Fan Current
Total Bath Fill Volume
HEX Temperature
By-pass Servo Position
Burner Thermistor Temperature
Intake Air Temperature
Thermal Fuse
Thermal Couple Value
Frozen Sensor Temperature 1
Frozen Sensor Temperature 2
UNIT
0.1 gal/min
Deg. F
X100
X100
Hertz
Controller ID
MEANING
GPM Flowing
Outgoing Temp.
Combustion Time
Combustion Freq.
Fan Hertz
Deg. F
10 mA
Gallons
Deg. F
Degree Position
Deg. F
Deg. F
Deg. F
mV
Deg. F
Deg. F
Incoming Temp.
Volume of water fill
Temperature of HEX
By-Pass Position Degree
*Water Flow Servo Position
If the controller reads "1", this means the water flow servo is open.
If the controller reads "2", this means the water flow servo is closed
48If the controller reads "0", this means the water flow servo fluctuates (partially opened and partially closed)
Please Note:
The 01-18 codes will
not be present on every
model. Some codes
are for indoor models
will not show up on
the controllers of an
outdoor unit.
or
Condensing and Non
Condensing Product
Error Codes
&
Troubleshooting
49
Diagnostic Codes
A 2-digit maintenance code will flash on the temperature controller when water is flowing.
See owner's manual for a details.
50
(Continued on next page)
Diagnostic Codes
51
(Continued on next page)
Diagnostic Codes
52
(Continued on next page)
Diagnostic Codes
LC code reset for VC and KB model units
•
•
53
After Flushing unit , the procedure to reset LC codes:
Push the two switches (A & B) on PCB at the same time for 5 seconds.
• Unit will return to normal operation and LC# count returns to 0.
FF – To enter this maintenance flag code in history, press the up, down,
and ON/OFF simultaneously
Maintenance Diagnostic Codes
Wiring Diagram
EZConnect
Freeze Protection Thermistor
Freeze Protection Thermistor 2
51
Inlet Thermistor
79
Water leak detector
Outgoing
Thermistor
32
HEX Thermistor
33
Water level electrode
25
Water flow sensor
61
BMS/AH Plug
Combustion fan
MSB Plug
Flame rod
11, 12, or 72
Anti-Freeze Plug
Modulating solenoid valve
Over heat switch #1
Thermo-fuses
14, 57, 58
OH switch #2
OH switch #2
OH switch #3
Built-in
Controller
31 or 73
TC Sensor7
Color coding
BK - Black
BR - Brown
R - Red
O - Orange
Y - Yellow
G - Green
B - Blue
PR- Purple
GY- Grey
W - White
P - Pink
71
Spark electrode
igniter
54
120 Volt Power
Supply 10 amps
70 = Defective PC board
By-pass Servo
Control Devise
05
Water Flow
Servo Valve
65
Freeze Protection Operation
1. Ceramic heaters throughout unit (see oblong red
circles) turn on at 39 ˚F, off at 45 ˚F on internal units.
External units activate at 37 ˚F on, 45 ˚F off.
Ceramic circuit operates on 120 VAC.
Thermistor #2
2. There are two thermistors on the internal unit that
control the freeze protection. They are fed from
connector “E” on the PC board. Thermistor #1 is fed
from pin #11 (yellow wire) and pin #4 (grey).
Thermistor #2 fed off pin #14 (yellow wire) and pin
#4 (grey). Thermistor #2 is location in the vent intake
chamber at the top of the unit, thermistor #1 sticks
out of the bottom of the unit, see small red circles at
thermistor locations.
3. The external unit only has one thermistor that
controls the ceramic heaters. It is fed from connector
“E” off the PC board from pin #11 (yellow wire) and
pin #4 (grey).
4. Condensing models do not dry fire as the noncondensing product does. They are equipped with
additional ceramic heaters. NOTE: Adequate
incoming power and gas are required for freeze
protection to operate correctly!
55
Thermistor #1
Reasons for Heat Exchanger Failure
When all installation guidelines are followed, the heat exchanger should last for many years.
Primary reasons heat exchangers fails are as follows:
Freezing damage
Rinnai indoor water heaters have
internal protection when outside
temps are as cold as -22°F
(-30°C)—outdoor when outdoor
temps are as cold as -4°F
(-20°C) provided adequate
power and gas supplies are
present. Employ the optional drain
down configuration if needed.
Condensation from incorrect
venting
High efficiency appliances create
condensation. Incorrect venting
not only can cause operational
issues and shortened vent life,
but the highly acidic condensation
will corrode water heater
components including the heat
exchanger.
Internal scaling from poor water quality
Inadequate water quality creates
internal insulation issues which can
affect performance and eventually
deteriorate the copper tubing. Higher
operating temperatures can
exasperate this condition. Ensure the
water quality meets the National
Secondary Drinking Standards Act
(EPA Guideline).
THESE
ARE INSTALLATION AND/OR APPLICATION ISSUES THAT MUST BE CORRECTED TO
56
PREVENT RECURRENCE OF THE FAILURE — NOT WARRANTY CLAIMS
Water Requirements
57
Troubleshooting Water Flow Issues
• Cold water sandwich is when a tankless water heater is turned on, off,
and on again in a short period of time. Due to the 3-5 second activation
time, this causes a cold slug of water to travel down the hot water pipe.
• Crossover is when cold water is introduced into the hot
water line after the water heater. When this happens, it
can “overtake” the flow from the tankless water heater,
thus causing the temperature at the output to scale
back.
• If strong enough, the crossover can cause the unit to
turn off altogether for a brief moment. Crossover can
occur in single handled mixing valves, washing
machine connections, anywhere there is hot and cold
introduced at a single point.
• Pressure regulated and scald prevention fixtures can also cause intermittent flow issues.
• Clogged water filters, sink aerators, filtration systems, etc. can also cause flow issues.
• Troubleshooting tip: If after isolating the appliance from the plumbing system and the output
temperature is verified through the controller’s diagnostic tests, the unit is likely performing to
manufacturer’s specifications.
58
Flush Procedure
For proper operation, unit longevity, and warranty adherence, water
supply to the water heater must meet National Secondary Drinking
Water Standard. In areas with hard water, a water softener or other
treatment systems are needed. A periodic flushing may be required.
Below is the proper flushing procedure:
1. Disconnect electrical power to the water heater
2. Close the shutoff valves on both the hot and cold water lines (V3 and V4)
3. Connect pump outlet hose (H1) to the cold water line at service valve V2
4. Connect drain hose (H3) to service valve V1
5. Pour approximately 4 gallons of virgin food grade white vinegar or citric acid into pail
6. Place the drain hose (H3) and the hose (H2) to the pump inlet into the cleaning solution
7. Open both service valves (V1 and V2) on the hot and cold water lines
8. Operate the pump and allow the cleaning solution to circulate through the water heater
for at least 45 minutes
9. Turn off the pump
10. Rinse the cleaning solution from the water heater by:
a. Remove the free end of the drain hose (H3) from the pail, place in suitable
drain.
b. Close service valve, V2, and open shutoff valve, V4. Do not open shutoff
valve, V3.
c. Allow water to flow through the water heater for 5 minutes
d. Close service valve, V1, and open shutoff valve, V3
11. Disconnect all hoses
12. Shut off V4, then remove the in-line filter at the cold water inlet and clean out any
residue.
a. Place the filter back into the unit, open valve V4.
59
13. Restore electrical power to the water heater
Water Quality
Study Highlights:
…- Hard water can lead to as much as a 48% loss of
efficiency in (gas tank-type) water heaters.
Batelle Testing Labs
Water Quality Report
- Each five grains per gallon of hardness causes an 8%
loss in efficiency and 8% increase in cost when using
100 gallons of hot water per day in a gas storage tank
water heater. On 30 grains per liter (gpl) hard water,
that’s 48% less
efficient than with softened water.)
- Tankless gas water heaters operated on softened
water maintained the original factory efficiency rating
over a 15-year lifetime.
- Softened water saves 34% of costs compared to
operating on 20 gpl and saves 47% compared to
operation on 30 gpl hard water.
Remember - incoming water maximum hardness threshold
for Rinnai Tankless water heaters is 11.7gpl - so the above
values are extreme - but they do exist in some areas.
- The moral of the story: Know the hardness levels in
your area, perform the recommended flushing
procedure as needed, and recommend the use of a
60
water
softener if needed as well.
Source: http://wqa.org/pdf/pressreleases/battelleresults.pdf
Gas Requirements,
and
Troubleshooting
61
Gas Supply Sizing Procedure - Example
The following example is known as the longest length method. A full explanation of NG and LPG pipe sizing can be
found in the National Fuel Gas Code Manual
1.
Determine the maximum gas (Btu) input for each appliance
(see rating plate of appliance)
2.
The total length of pipe from the point of delivery to the farthest
appliance is 60 ft. This is the only distance used (longest
length).
3.
Refer to the appropriate table in the NFPA 54 manual. This will
depend on type of pipe, type of gas, inlet pressure, pressure
drop, and specific gravity. See below example:
The below example has the following parameters:
Gas: NG
Inlet pressure: less than 2 PSI
Outlet D
furnace
100,000 Btu/hr
Outlet C
tankless water
heater
199,000 Btu/hr
Schedule 40 Metallic Pipe, Natural Gas, less than 2 psi inlet pressure,
0.5” w.c. pressure drop, 0.60 specific gravity
Section 2 - 20 ft
Pipe Size (in.)
Nominal:
Length (ft)
4.
½
¾
1
1 ¼” pipe
1¼
1½
Capacity in Cubic Feet of Gas per Hour (CFH=Btu/1000)
10
172
360
678
1390
2090
20
118
247
466
957
1430
30
95
199
376
768
1150
40
81
170
320
657
985
50
72
151
284
583
873
60
65
137
257
528
791
70
60
126
237
486
728
Using the row marked 60 ft in the above excerpt from table 6.2.(b):
Section 3
1 ¼” pipe
10 ft
20 ft
¾” pipe
½” pipe
10 ft
Section 1
15 ft
15 ft
¾” pipe
5 ft
Point of Delivery
(gas meter)
a) Outlet A, supplying 30 cfh (30,000 Btu), requires ½” pipe
b) Outlet B, supplying 75 cfh (75,000 Btu), requires ¾” pipe
c) Section 1, supplying outlets A and B, or 105 cfh (105,000 Btu), requires ¾” pipe
d) Section 2, supplying outlets C and D, or 299 cfh (299,000 Btu), requires 1 ¼” pipe
e)62Section 3, supplying outlets A, B, C, and D, or 404 cfh (404,000 Btu), requires 1 ¼” pipe.
Outlet B
range/oven
75,000 Btu/hr
Outlet A
gas fireplace
30,000 Btu/hr
Gas Supply Sizing Procedure
1.
Determine the maximum gas (Btu) input for each appliance
(see rating plate of appliance)
2.
The total length of pipe from the point of delivery to the farthest
appliance is 60 ft. This is the only distance used (longest
length).
3.
Refer to the appropriate table in the NFPA 54 manual. This will
depend on type of pipe, type of gas, inlet pressure, pressure
drop, and specific gravity. See below example:
The below example Intended use is with initial supply
pressure of 8”w.c. or greater.
Schedule 40 Metallic Pipe, Natural Gas, less than 2 psi inlet pressure,
3.0” w.c. pressure drop, 0.60 specific gravity
Section 2 - 20 ft
¾” pipe
Pipe Size (in.)
Nominal:
Length (ft)
4.
½
¾
1
1¼
1½
Outlet D
furnace
100,000 Btu/hr
Outlet C
tankless water
heater
199,000 Btu/hr
Section 3
½” pipe
1 ” pipe
½” pipe
Capacity in Cubic Feet of Gas per Hour (CFH=Btu/1000)
10
454
949
1,787
3,669
5,497
20
312
652
1,228
2,522
3,778
30
250
524
986
2,025
3,034
40
214
448
844
1,733
2,597
50
190
397
748
1,536
2,302
60
172
360
678
1,392
2,085
70
158
331
624
1,280
1,919
Using the row marked 60 ft in the above excerpt from table 6.2.(c):
10 ft
20 ft
10 ft
Section 1
15 ft
15 ft
½” pipe
Point of Delivery
(gas meter)
a) Outlet A, supplying 30 cfh (30,000 Btu), requires ½” pipe
b) Outlet B, supplying 75 cfh (75,000 Btu), requires ½” pipe
c) Section 1, supplying outlets A and B, or 105 cfh (105,000 Btu), requires ½” pipe
d) Section 2, supplying outlets C and D, or 299 cfh (299,000 Btu), requires ¾” pipe
e)63Section 3, supplying outlets A, B, C, and D, or 404 cfh (404,000 Btu), requires 1” pipe.
Outlet B
range/oven
75,000 Btu/hr
Gas System - Two stage piping Example
If resizing gas supply lines is not a feasible option, a two stage supply system may be used depending on
local code guidelines. Two stage systems operate in the following manner:
• Higher pressure (usually 2 lbs or
approximately 56” w.c.) is supplied for a large
portion of the supply system.
• Regulators are placed close to each appliance
to reduce pressure to the appliance standard
of ½ lb or approximately 7-14” w.c.
• This system overcomes volume inadequacies
by raising the pressure. NOTE: Never apply
high pressure (such as 2 lbs) to a household
appliance unless stated by the manufacturer.
All Rinnai tankless water heaters require no
more than ½” lb inlet pressure (14” w.c.).
The below example has the following parameters
Gas: NG
Inlet pressure: 2 PSI
Outlet C
tankless water
heater
199,000 Btu/hr
Outlet D
furnace
100,000 Btu/hr
Main gas meter
supplies 2 lbs of
pressure through
existing pipes
Regulators are placed in
close vicinity to all appliances
bringing pressure to appliance
standard (1/4-1/2 lb)
• Using the previous example, if the existing
gas line did not meet the NFPA standard for ½
lbs pressure, the following two stage
implementation could be an alternative
• Follow NFPA 54 guideline and all code
requirements when sizing two stage systems.
• Two stage systems can be used in NG or LP
applications—sizing values differ by gas type
• Gas meter capacity must also be considered
64
Point of Delivery
(gas meter)
Outlet B
range/oven
75,000 Btu/hr
Outlet A
gas fireplace
30,000 Btu/hr
Gas Supply Sizing Procedure - Troubleshooting
Issues caused by insufficient gas supply:
-
Poor appliance operation
-
Error code 10, 11 and 12’s.
-
Rumbling noises due to insufficient air/gas mixture (this will also occur with
incorrect venting)
Installation may operate correctly until winter, then furnace kicks on and gas demand
increases. Now gas system is determined to be undersized due to not taking into
account gas load at full capacity.
-
- If symptoms exist suggesting a gas supply issue as mentioned above you will
need a gas manometer to verify the incoming gas pressure. Various manometers are
available for testing gas pressure, see two examples below.
U-tube or
Slack tube
manometers
65
Digital
manometers
Dip Switch Settings at Altitudes
Dip Switch Settings
Adjust dip switch #2 and #3 at SW1 (tan
switches) for your altitude according to the
table below. Factory default is set for 0 –
2,000 foot in elevation. Once the dip switches
are set per the table below, the gas pressures
are automatically adjusted by the appliance.
High altitude
66
SW1
SW2
Gas Pressure Settings at Altitude
Refer to the chart below for internal unit gas pressure settings in the event
a gas valve or PC board was replaced or if you are just verifying settings.
67
Gas Pressure Settings at Altitude
Refer to the chart below for external unit gas pressure settings in the event
a gas valve or PC board was replaced or if you are just verifying settings.
68
Setting Gas Pressure
Gas Pressure Setting - Ensure gas system is properly sized before proceeding. The
water heater’s regulator is electronically controlled and factory pre-set. Under normal
circumstances it does not require adjustments during installation. Make adjustments only if
the unit is NOT operating correctly and all other possible causes for incorrect operation
have been eliminated.
SW1
1.
2.
3.
4.
Turn off the gas supply.
Turn off the water supply.
Remove the front panel (4 screws).
Check the gas type using the data plate on the side of the unit. Confirm that the gas
type switch is in the correct position, (switch 1 of Dip SW2 (white row of dip switches) is
ON for natural gas and OFF for propane gas (LPG). See picture to right showing SW2.
5. Remove the burner test port screw at the manifold and attach the manometer, Figure 2.
6. Turn on the gas supply and power supply.
7. Flow water through the water heater at the maximum flow rate obtainable, (at least 3
gallons per minute is recommended. If there is not enough water flowing the water
heater could shut off or sustain damage due to overheating).
8. Move dip switch 8 in SW1 to ON, Figure 3.
9. Push the PC board switch A for one second. Figure 4.
10. Calibrate “Forced Low” combustion using switch A (up) and Switch B (down).
11. Move switch 8 of Dip switch SW1 to OFF and then back to ON, figure 6.
12. Push PC board switch B for one second, figure 4.
13. Calibrate “Forced High” combustion using switch A (up) and switch B (down).
14. Move switch 8 of Dip SW1 to OFF, figure 5.
15. Close hot water tap.
16. Turn off gas and 120 volt power supply.
17. Remove manometer and re-install Phillips head screw, make sure O-ring is intact.
18. Turn on the gas supply and 120 volt power supply.
19. Operate the unit and check for gas leaks.
20. Install the front panel using four screws.
69
SW2
Manometer
connection
point
Condensing Model
Venting
Requirements
! WARNING
Improper installation of vent system and components, or failure to follow all installation instructions, can result in
property damage or serious injury
Rinnai’s installation instructions AS WELL AS each venting manufacturer’s instructions should be followed. If any
guideline or stipulation differs between Rinnai and the venting manufacturer, please adhere to the guideline that is more
stringent.
Please review Rinnai’s Venting Instructions provide with the vent terminations for more detailed venting
guidelines
70
Vent Length Calculator
Vent Length Example
Elbow Length Calculator
Add the total length of
all vent pipe and the
equivalency of all bends:
= 6 Feet
Each 90° bend is equivalent to 6 feet of vent pipe
3’ (termination)
+3’ (bend)
+2’ (extension)
+3’ (bend)
+2’ (extension)
13 foot equivalency
= 3 Feet
Each 45° bend is equivalent to 3 feet of vent pipe
O
F
F
Total equivalency vent length cannot exceed
41 feet. If the equivalency is greater than 21
feet move DIP switch #1 in SW1 to the OFF
position, switch is in the ON position from
factory)
→ ON
1
2
3
4
5
6
7
8
S
w
i
t
c
h
In this example,
DIP switch #1
would remain in
the ON position
3 feet
45° bend = 3
feet
2 feet
45° bend = 3
feet
2 feet
N
u
m
b
e
r
Refer to Ubbink’s venting instruction manual for details on proper venting and
clearances.
71
Vent Termination
The diagrams below illustrate the correct way to address venting horizontally or vertically using the Ubbink
concentric style venting. The vent system for the appliance MUST be sloped back towards water heater at
a 1 degree pitch or ¼” per foot minimum. MUST use Polypropylene (PP) venting materials with all Rinnai
condensing water heaters. See venting instructions for details on proper venting.
Condensate direction
Condensate direction
72
Rinnai Vent Termination Clearances
Vent terminal represents concentric vent terminal. =
V
12” (30 cm)
between
Rinnai
terminals at
the same level
36” (.91 m) to
ventilated or
unventilated
soffit or eve
vent; or to a
deck or porch
60” (1.52m)
between Rinnai
terminals at
different levels
12” (.30 m) to an
inside corner
12” (30 cm)
between Rinnai
terminals at the
same level
60” (1.52m)
vertically between
Rinnai terminals
(Also applies to
external models)
The above clearances also
apply to external models.
73
• Avoid terminations near a dryer vent
• Avoid terminations near commercial
cooking exhaust
• Comply with local and state codes as
required
Troubleshooting Summary
• Remember all resources available to you!!
- Rinnai documentation (Tech Service and Installation Manuals, Tech Data Sheets, Knowledge
base)
- Rinnai Support
a. Technical Support and Engineering – at 1(888)746-6247 or 1(800)621-9419
b. Local Support (Sales representatives, distributors, etc.)
- Rinnai Websites
• Remember the quality of the product!!
-
Rinnai’s Quality Control is second to none, every unit is fired three times before leaving the
factory
If it is a new install, realize the improbability of a manufacturing issue
• Remember the basics!!
- Make certain all input parameters are good - water, gas, electricity, and air (venting)
- If after isolating the appliance from the plumbing system and gpm flow and output temperature
are verified through the controller’s diagnostic tests, the unit is functioning as designed, the
problem is in your plumbing system.
74
General Trouble Shooting Summary
Basic Troubleshooting
this is a general guide and not intended as an official troubleshooting procedure - contact Rinnai technical support if needed.
GAS
Verify incoming
pressure
Is there a large drop from static
indicating volume/line
sizing/regulator/meter issues?, Were all
appliances operating during test?, Has
the gas line been over-pressurized?,
Are altitude adjustments needed?
AIR
ELECTRICITY
Verify correct venting
Verify input power
Verify correct parts, seals, custom cuts,
termination clearances, internal airways,
high altitude/cold climate adjustments
(Is there adequate power to PCB?, Is
incoming polarity correct? Is there a
sufficient ground?
WATER
Verify flow
(with unit isolated)
(Is the flow in right direction?, Verify no back
flow?, is the filter/turbine clean?, etc.)
Verify DC power
Verify clean fan
Is the fan sealing correctly?, etc.)
Will the unit fire with no controller? Will
the controller light with nothing else
plugged into PCB?, Will the controller
light with no extra thermostat wire?
Verify incoming water
temperature
(make sure delta T is accurate, Is flushing
needed?, Are thermistor bulbs clean?, etc.)
Verify clean burner area
Is there any condensation debris…why?, signs of leakage….why, Is the flame
rod/sparker clean and properly oriented?
Verify grounding
(Is the ground good through entire
circuit?, Have any internal wires been
shorted to ground?
Verify manifold pressure
If the gas valve was removed, are all solenoids
plugged in correctly?
Verify pressure/pipe size
Verify application
Verify all wiring/harnesses
(check all harnesses for damage—i.e. water, corrosion, shorts/opens?, etc.)
Could issue be application related
(pump sizing, check valve
location/orientation, etc.)
Is the problem environmental? (time of day?, weather?, etc.)
Confirm the information? Have you witnessed the symptom?, is your meter or manometer connected/setup correctly? Are the meter probes making good contact?
75 If SERVICE OR INSTALLATION assistance is needed in diagnosing the operation of the product, contact Rinnai technical support at 1-888-RINNAIS
The End
Rinnai
Service Fundamentals
Level III KB Series Product
www.rinnai.us