A.O. Smith RPV series Product information sheet

Electric Tankless
Water Heater
Keep this manual near the water heater for future reference whenever maintenance, adjustment or service is required.
Retain your original receipt as proof of purchase.
IMPORTANT SAFETY INFORMATION.............................2
GENERAL INFORMATION ...............................................5
INSTALLATION ............................................................... 11
OPERATION ...................................................................15
TROUBLESHOOTING ....................................................17
SERVICE .........................................................................22
WIRING DIAGRAMS .....................................................29
APPENDIX...................................................................... 34
Table of Contents ..............................Page
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ENTER
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ENTER
PLEASE DO NOT RETURN THIS UNIT TO THE
STORE.
Read this manual and the labels on the water heater before you install,
operate, or service it. If you have difficulty following the direcons, or
aren’t sure you can safely and properly do any of this work yourself:
• Call our Technical Support Hotline:
United States: 1-877-817-6750
Canada: 1-800-265-8520
We can help you with installation, operations, troubleshooting, or
maintenance. Before you call, write down the model and serial number from
the water heater’s data plate.
• Incorrect installaon, operaon, or service can damage the water heater, your
house and other property, and present risks including fire, scalding, electric
shock, and explosion, causing serious injury or death.
0618
100306524_2000558984 (REV. A)
Installaon Instrucons
and Use & Care Guide

SAFETY
2 • Electric Tankless Water Heater
IMPORTANT SAFETY INFORMATION
Important informaon to keep...
Fill out this secon and keep this
manual for reference.
Date Purchased:
Model number:
Serial number:
Maintenance performed: Date:
This is the safety alert symbol. It is used to alert you to
potenal physical injury hazards. Obey all safety mes-
sages that follow this symbol to avoid possible property
damage, serious injury or death. Do not remove any
permanent instrucons, labels, or the data plate from either the outside of
the water heater or on the inside of the access panels. Keep this manual
near the water heater.
DANGER
Read and follow all safety messages and instrucons in
this manual.
DANGER indicates hazardous
situaon that, if not avoided, will
result in death or serious injury.
WARNING WARNING indicates a hazardous
situaon that, if not avoided, could
result in death or serious injury.
CAUTION CAUTION indicates a hazardous
situaon that, if not avoided, could
result in minor or moderate injury.
NOTICE NOTICE indicates pracces not
related to physical injury.

SAFETY
Electric Tankless Water Heater • 3
To reduce the risk of property damage, serious injury or death,
read and follow the precauons below,
all labels on the water heater, and
the safety messages and instrucons
throughout this manual.
General Requirements
• Install and properly ground the
unit in accordance with local
codes, or in the absence of local
codes, with the current edition
of the National Electrical Code:
ANSI/NFPA 70 in the USA or
CSA standard C22.1 Canadian
Electrical Code, Part 1 in Canada.
• Follow all applicable plumbing,
heating, and air conditioning
codes during installation.
RISKS DURING INSTALLATION
AND MAINTENANCE
WARNING
Electric Shock Risk
Contact with the electrical
parts inside the water heater
can result in severe injury or
death from electrical shock:
• Disconnect power by opening the
circuit breaker(s) before installing
or servicing.
• SOME MODELS ARE CONNECTED
TO MORE THAN ONE BRANCH
CIRCUIT, AND MORE THAN ONE
DISCONNECT SWITCH MAY BE
REQUIRED TO DEENERGIZE THE
EQUIPMENT. ALL BRANCH CIR
CUITS MUST BE DISCONNECTED
PRIOR TO SERVICE.
• Use a non-contact circuit tester to
confirm that power is off before work-
ing on or near any electrical parts.
• Be sure the cover is reinstalled and
secured after servicing to reduce
the risk of fire and electric shock.
RISKS DURING OPERATION
WARNING
Scalding Risk
This water heater
can make water hot
enough to cause
severe burns instantly, resulting in
severe injury or death.
• Feel water before bathing or
showering.
• To reduce the risk of scalding,
install Thermostatic Mixing
Valves (temperature limiting
valves) at each point of use.
These valves automatically mix
hot and cold water to limit the
temperature at the tap. Mixing
valves are available at your local
hardware store or from your
plumbing supplier. Follow the
manufacturer’s instructions for
installation and adjustment of the
valves.
• For all models, the temperature
set point is factory set to 120°F
to reduce the risk of scalding.
Exception: single chamber (point-
of-use) models are factory set to
approximately 105°F.
• Higher temperatures increase
the risk of scalding, but even at
120°F, hot water can scald. If you
choose a higher temperature,
Thermostatic Mixing Valves
located at each point of use are
particularly important to help
avoid scalding.
Temperature Time to Produce a
Serious Burn
120°F (49°C) More than 5 minutes
125°F (52°C) 1½ to 2 minutes
130°F (54°C) About 30 seconds
135°F (57°C) About 10 seconds
140°F (60°C) Less than 5 seconds
145°F (63°C) Less than 3 seconds
150°F (66°C) About 1½ seconds
155°F (68°C) About 1 second
For information about changing the
factory temperature setting, refer to
“Water Temperature Adjustment” on
page 15.
Even if you set the water heater set
point to a low seng, higher tem-
peratures may occur in certain circum-
stances:
• Water temperature will be hotter if
someone adjusted the temperature
set point to a higher setting.
• If the water supplied to the water
heater is pre-heated (for example,
by another water heater), the tem-
perature of the water may be high-
er than the temperature set point.
• Problems with the UIM (user
interface on two- or four-chamber
models) or other malfunctions may
result in higher than expected water
temperatures.
To reduce the risk of unusually hot wa-
ter reaching the fixtures in the house,
install Thermostac Mixing Valves at
each point of use.
If anyone in your home is at parcular
risk of scalding (for example, the el-
derly, children, or people with disabili-
es) or if there is a local code or state
law requiring a certain water tempera-
ture at the hot water tap, then these

SAFETY
4 • Electric Tankless Water Heater
precauons are parcularly important.
According to a naonal standard, Ameri-
can Society of Sanitary Engineering
(ASSE 1070), and most local plumbing
codes, the water heater’s temperature
set point should not be used as the sole
means to regulate water temperature
and avoid scalds.
Properly adjusted Thermostac Mixing
Valves installed at each point of use
allow you to set the water heater’s
set point to a higher seng without
increasing the risk of scalds. A higher
temperature can help provide proper
water temperatures for appliances such
as dishwashers and washing machines.
WARNING
Fire Risk
To reduce the risk of a
fire that could destroy
your home and seri-
ously injure or kill people:
• Do not store things that can burn
easily such as paper or clothes next
to the water heater.
• Be sure the water heater’s cover
is in place. This cover keeps debris
from entering and potentially being
ignited, and helps keep any internal
fires from spreading.
• Keep the water heater from becom-
ing wet. Immediately shut the water
heater off and have it inspected by
a qualified person if you find that
the wiring or control board have
been exposed to water in any way
(e.g., leaks from plumbing or leaks
from the water heater itself). Such
leaks can damage property and
could cause a fire risk. If the water
heater is subjected to flood condi-
tions or has been submerged in
water, the entire water heater must
be replaced.
• Make electrical connections prop-
erly according to the instructions on
page 13. Use a UL listed or CSA
approved strain relief. Connect the
ground wire to the ground lug. (The
ground lug is identified by a green
and white ground label inside the
water heater.)
Water Contamination Risk
Do not use chemicals that could
contaminate the potable water sup-
ply. Do not use piping that has been
treated with chromates, boiler seal, or
other chemicals.

GENERAL INFO
Electric Tankless Water Heater • 5
GENERAL INFORMATION
Introduction
• This manual provides information
necessary for the installation,
operation, and maintenance of
the water heater.
• The model description is listed on
the rating plate which is attached
to the side panel of the water
heater.
• Please read all installation
instructions completely before
installing this product.
• If you have any problems
or questions regarding this
equipment, consult the
manufacturer or its local
representative.
This appliance is an on-demand,
electric tankless water heater. It is
designed to efficiently supply endless
hot water for your needs.
A built-in alarm is included. If water
leaks inside your electric water
heater, an alarm will sound to provide
warning. Simply turn off power to the
water heater at the circuit breakers,
turn off the water supply, then correct
the leak.
Your water heater also includes
on-board self diagnostics. If the
system produces an error code, see
“Troubleshooting” on one of the
following pages:
• Point-of-use models: page 17.
• Two- or four-chamber models:
page 19.
Component
Descriptions
Temperature and Pressure
Relief Valve
In most cases, you are not required
to install a temperature and pressure
relief valve (T&P valve). However,
some local codes do require the
installation of a T&P Valve. If a T&P
valve must be installed, install it on
the hot outlet pipe according to the
valve manufacturer’s instructions and
local code.
If you install a T&P valve, turn on the
water supply to ensure that no water
drips from it. Next, operate the valve
manually two or three times to purge
the trapped air from the top of the
heater’s chamber, then close the
valve. Verify that water has stopped
flowing completely before connecting
the discharge pipe to the valve.
NOTICE: If a temperature and
pressure relief valve is installed, it
must be piped by minimum 1 inch
pipe to a suitable drain capable of
discharging 10 GPM. A splash cover
must be included to protect the
area of attachment to the wall. The
manufacturer will not be responsible
for any water damage that may occur.
WARNING! Do not cap or plug the
T&P relief valve or discharge pipe.
Component Identification: Point-of-Use Models (RPV, CPV)
POWER
SUPPLY
TERMINAL
BLOCK
L1
L2/N
GND
T-Aux
T-In
T-Out
T-Aux Auxiliary thermistor
T-In Inlet thermistor
T-Out Outlet thermistor
Thermistor* Connections
OUTLET INLET
Outlet Thermistor *
(Connects to T-Out)
Auxiliary Thermistor *
(Connects to T-Aux)
Inlet Thermistor *
(Connects to T-In)
* Often referred to
as a temperature
sensor.
Heating Element
(Behind inlet/outlet)
Continued on the next page...

GENERAL INFO
6 • Electric Tankless Water Heater
Component Identification: Two-Chamber Models (R2V, C2V)
Inlet Thermistor *
(connects to TH-IN)
OUTLET INLET
TH-IN Inlet thermistor
TH-1 Intermediate thermistor
TH-2 Outlet thermistor
Thermistor* Connections
* Often referred
to as a
temperature
sensor.
L1
L2
TH-1
TH-IN
Intermediate
Thermistor *
(connects to
TH-1)
Outlet Thermistor *
(connects to TH-2)
HEATING ELEMENTS
Access Plate
(for draining)
TH-2
NOTICE:
The user interface is
described in Figure 7,
page 16.
Component Identification: Four-Chamber Models (R4L, C4L, R4M, C4M)
Inlet Thermistor *
(connects to TH-IN)
INLET
L1
L2
TH-1
TH-3
TH-4
Intermediate
Thermistor *
(connects to
TH-1)
TH-2
TH-IN
L1
L2
TH-IN Inlet thermistor.
TH-1 Intermediate thermistor
TH-4 Outlet thermistor
Thermistor* Connections
* Often referred to as a
temperature sensor.
TH-2 Intermediate thermistor
TH-3 Intermediate thermistor
OUTLET
Outlet Thermistor *
May be located on
outlet elbow.
(connects to TH-4)
Intermediate Thermistor *
(connects to TH-3)
Intermediate
Thermistor *
(connects to
TH-2)
Access Plates
(for draining)
Element Element Element Element
NOTICE:
The user interface is
described in Figure 7,
page 16.

GENERAL INFO
Electric Tankless Water Heater • 7
Models Point-of-Use:
RPV, CPV
Two Chamber:
R2V, C2V
Four Chamber:
R4L, C4L, R4M, C4M
Wiring & Circuit Breaker
Requirements See “Electrical Requirements” on page 8.
Water Connections 3/4” NPT 3/4” NPT 3/4” NPT
Weight
lbs. (kg) 8 lbs. (3.6 kg) 13 lbs. (5.9 kg) 20 lbs. (9 kg)
Water Heater
Dimensions*
H 16-5/8” x W 6-1/2” x D 7-3/16”
(H 42.2cm x W 16.5cm x D 18.3 cm)
H 17-3/4” x W 11-1/2” x D 6-1/8”
(H 45.1 cm x W 29.2 cm x D 15.6 cm)
H 18-1/8” x W 17” x D 6-1/8”
(H 46 cm x W 43.2 cm x D 15.6 cm)
* Height dimension includes the distance from the bottom of the heater to the highest point of the inlet/outlet.
Width dimension includes the mounting tabs on the left-hand and right-hand sides (two- and four-chamber models).
NOTE:
• Check the rating plate to ensure this product matches your specifications.
• The manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and
without incurring obligations.
• The maximum working pressure is 150 psi. The water supply pressure should not exceed 80 psi. If this occurs, a pressure
reducing valve with a bypass should be installed in the cold water inlet line.
• Maximum flow may require water pressure equal to or greater than 40 psi.
General Specifications

GENERAL INFO
8 • Electric Tankless Water Heater
Electrical Requirements
• Follow these steps to determine the electrical requirements for your water heater:
1.) Find your model number on your water heater’s rating plate.
2.) Locate that model number in one of the tables listed below.
For example, if your model is RPVA-24-K5, find *P**-24-K5 in the appropriate table.
Models within each table are sorted by Voltage first, then by Wattage per Element (KW).
• Follow the requirements listed for your model.
□Point-of-use models are listed below.
□Two-chamber models: page 9.
□Four-chamber models: page 10.
• Use copper conductors only.
Point-of-Use Models
(For potable water heating only. Not for space heating.)
NOTICE: Models sorted by Voltage, then by Wattage per Element.
Model Recommended
Breaker Size
(Amps)
Voltage Number
of
Elements
Wattage
per Element
(KW)
Current per
Breaker
(Amps)
Recommended
Wire Size*
(AWG)
Element Type
*P**-24-K5 25 120 12.4 20.00 10 Single
*P**-30-K5 30 120 1325.00 10 Single
*P**-35-K5 30 120 13.5 29.17 10 Single
*P**-40-X5 20 208 1419.23 12 Single
*P**-78-X5 40 208 1837.5 8 Single
*P**-35-E5 20 240 ‡13.5 14.58 12 Single
*P**-45-E5 20 240 ‡14.5 18.75 12 Single
*P**-55-E5 25 240 ‡15.5 22.92 10 Single
*P**-70-E5 30 240 ‡1729.17 10 Single
*P**-80-E5 40 240 ‡1833.33 8 Single
*P**-90-E5 40 240 ‡1937.50 8 Single
*P**-120-E5 60 240 ‡112 50 6 †Dual
*P**-30-Y5 15 277 1310.83 14 Single
* All wiring/conductors must be rated for 90°C or greater.
† Maximum recommended wire size is #6 cu AWG.
‡ This model may used with a 208 VAC supply. Use of 208 VAC may require different breaker and/or wire sizes.
Follow all code requirements.

GENERAL INFO
Electric Tankless Water Heater • 9
Point-of-Use Models
(For potable water heating only. Not for space heating.)
NOTICE: Models sorted by Voltage, then by Wattage per Element.
Model Recommended
Breaker Size
(Amps)
Voltage Number
of
Elements
Wattage
per Element
(KW)
Current per
Breaker
(Amps)
Recommended
Wire Size*
(AWG)
Element Type
*P**-40-Y5 20 277 1414.44 12 Single
*P**-60-Y5 25 277 1621.66 10 Single
*P**-73-Y5 30 277 17.3 26.35 10 Single
*P**-90-Y5 40 277 1932.49 8 Single
* All wiring/conductors must be rated for 90°C or greater.
† Maximum recommended wire size is #6 cu AWG.
‡ This model may used with a 208 VAC supply. Use of 208 VAC may require different breaker and/or wire sizes.
Follow all code requirements.
Two-Chamber Models
(For potable water heating only. Not for space heating.)
NOTICE: Models sorted by Voltage, then by Wattage per Element.
Model Recommended
Breaker Size
(Amps)
Voltage Number of
Elements
Wattage per
Element (KW)
Current per
Breaker
(Amps)
Recommended
Wire Size*
(AWG)
Element
Type
*2**-140-X5 40 amps each
(2 circuits)
208 2733.65 8 Single
*2**-120-E5 60 amps 240 26.1 50 6†Single
*2**-140-E5 60 amps
240 2758.34 6†Single
*2**-160-E5 40 amps each
(2 circuits)
240 2833.33 8 Single
*2**-180-E5 40 amps each
(2 circuits)
240 2937.5 8 Single
* All wiring/conductors must be rated for 90°C or greater.
† Maximum recommended wire size is #6 cu AWG.

GENERAL INFO
10 • Electric Tankless Water Heater
Four-Chamber Models (Single Phase)
For potable water heating only. Not for space heating.
NOTICE: Models sorted by Voltage, then by Wattage per Element.
Model Recommended
Breaker Size
(Amps)
Voltage Number of
Elements
Wattage per
Element (KW)
Current per
Breaker
(Amps)
Recommended
Wire Size*
(AWG)
Element
Type
*4**-280-X5 70 amps each
(2 cirucits)
208 4767.31 6†Single
*4**-180-E5 40 amps each
(2 circuits)
240 44.5 37.50 8 Single
*4**-220-E5 50 amps each
(2 circuits)
240 45.5 45.83 6 Single
*4**-240-E5 60 amps each
(2 circuits)
240 4650.00 6†Single
*4**-280-E5 60 amps each
(2 circuits)
240 4758.33 6†Single
*4**-320-E5 70 amps each
(2 circuits)
240 4866.67 6†Single
* All wiring/conductors must be rated for 90°C or greater.
† Maximum recommended wire size is #6 cu AWG.