Rheem RUUD Iraining User manual

Heat Pump Water Heater
1
Table of Contents
INTRODUCTION............................................................................................................................... 3
SAFETY............................................................................................................................................ 3
Electrical..................................................................................................................................... 3
R410a Refrigerant....................................................................................................................... 3
Scalding....................................................................................................................................... 3
Flammable Vapors...................................................................................................................... 3
COMPONENT PARTS OF THE HEAT PUMP WATER HEATER ......................................................... 4
TOOLS........................................................................................................................................... 10
OPERATIONAL MODES ................................................................................................................. 11
Energy Saver Mode................................................................................................................... 11
Normal Mode............................................................................................................................ 11
Electric Heat Only..................................................................................................................... 11
Temperature Settings................................................................................................................ 11
WATER PUMP FLOW RATES ........................................................................................................ 12
EVAPORATOR FAN SPEED ............................................................................................................ 12
OPERATIONAL SAFETY CONTROLS –ALL MODES ...................................................................... 12
SEQUENCE OF OPERATIONS......................................................................................................... 13
Energy Saver Mode................................................................................................................... 13
Normal Mode............................................................................................................................ 14
Electrical Heat Only Mode ....................................................................................................... 15
SAFETY FUNCTIONS OF THE CONTROLS...................................................................................... 16
ECO (Energy Cut Off).............................................................................................................. 16
Power Outages.......................................................................................................................... 16
Heat Pump and Compressor Operations................................................................................... 16
TROUBLESHOOTING ..................................................................................................................... 16
Error Code LED Light.............................................................................................................. 16
Troubleshooting the Heat Pump Components.......................................................................... 17
TROUBLESHOOTING COMPONENT PARTS ................................................................................... 18
Upper or Lower Heating Elements........................................................................................... 18
Capacitor................................................................................................................................... 18
Transformer............................................................................................................................... 18
Thermistors (ambient, suction, discharge, water out, evaporator, upper tank and lower tank) 19
Fan Assembly............................................................................................................................ 19
Water Pump .............................................................................................................................. 19
Circuit Board............................................................................................................................. 20
Relay Switch............................................................................................................................. 20
DISASSEMBLY AND REPAIR .......................................................................................................... 21
Upper or Lower Heating Elements........................................................................................... 21
Upper ECO & Thermistor or Lower Thermistor...................................................................... 21
Capacitor................................................................................................................................... 22
Relays........................................................................................................................................ 22
Transformer............................................................................................................................... 22
Thermistors (ambient, suction, discharge, water out, evaporator, upper tank and lower tank) 22
Fan Assembly............................................................................................................................ 23

Heat Pump Water Heater
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Water Pump .............................................................................................................................. 23
Circuit Board............................................................................................................................. 23
WIRING CONNECTION DIAGRAM................................................................................................. 25
TEMPERATURE TO RESISTANCE THERMISTOR CHART .............................................................. 26
Index of Figures
Figure 1- HPWH Service Parts ...................................................................................................... 4
Figure 2 – User Control ............................................................................................................... 11
Figure 3 – Operating Modes......................................................................................................... 14
Figure 4 – Heating Element Electrical System............................................................................. 15
Figure 5 – Energy Cut Off............................................................................................................ 16
Figure 6 – Error Code LED.......................................................................................................... 16
Figure 7 - Capacitor..................................................................................................................... 18
Figure 8 – Transformer ................................................................................................................ 18
Figure 9 – Thermistor Connections.............................................................................................. 19
Figure 10– Fan Motor and Water Pump Connections................................................................. 19
Figure 11– Power Check.............................................................................................................. 20
Figure 12 - Relays......................................................................................................................... 20
Figure 13 – ECO & Upper Thermistor......................................................................................... 21
Figure 14– Replace Capacitor or Relays ..................................................................................... 22
Figure 15 – Replace Fan Assembly.............................................................................................. 23
Figure 16– Replace Water Pump.................................................................................................. 23
Figure 17– Replace Circuit Board ............................................................................................... 24
Figure 18– Wiring Diagram......................................................................................................... 25
Figure 19– Thermistor Resistance Chart ..................................................................................... 26
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 2009, Rheem Manufacturing Company, Water Heater Division.

Heat Pump Water Heater
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Introduction
This is a training manual not a job site service manual nor a parts manual. The intent of this
manual is to train users of the Heat Pump Water Heater manufactured by Rheem. This manual
does not assume any particular user liability, skill level, experience or expertise. The terms and
component parts used in this manual are current manufactured items or vendor provided items
used in Rheem Heat Pump Water Heater. Exercise care when installing and repairing electric
water heaters. Finally, we encourage all users to exercise good common sense and check your
local plumbing and electrical building codes.
Safety
Electrical
Troubleshooting and repairing a residential electric water heater can expose you to electrical
shock. Some of the diagnostic procedures require the presence of electricity. Use extreme
caution when performing these procedures. When replacing an unserviceable component, turn
off all power to the water heater and check for the presence of power with a multimeter or test
lamp.
R410a Refrigerant
This water heater contains a sealed gas refrigerant. Please check your local
licensing requirements to handle and service sealed refrigerant appliances.
Release of the refrigerant into the atmosphere may be considered illegal.
R-410A is an ozone-friendly refrigerant designed to replace R-22. R-410A refrigerant does not
contribute to ozone depletion. The Clean Air Act mandates that all HVAC equipment
manufacturers cease producing equipment with R-22 refrigerant on January 1, 2010.
Scalding
To comply with safety regulations the thermostats were set as 120° F before the water heater was
shipped from the factory. Households with small children, disabled, or elderly persons may
require a 120° F or lower thermostat setting to prevent contact with 'HOT' water and potential
scalding.
Flammable Vapors
Gasoline, as well as other flammable material and liquids (adhesives, solvents, etc.), and vapors
they produce are extremely dangerous. Do not handle, use or store gasoline or other flammable
or combustible materials anywhere near or in the vicinity of a water heater. The arc drawn in the
water heater controls can ignite these vapors. Failure to do so can result in property damage,
bodily injury or death.

Heat Pump Water Heater
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Component Parts of the Heat Pump Water Heater
Figure 1- HPWH Service Parts
Part Name Description Picture
User control
(14)
This panel allows for user
selection of water temperature
and operating mode.

Heat Pump Water Heater
5
Heat Pump
(not repairable)
A heat pump is a device for
transferring energy in the form
of useful heat from one place to
another. It cannot store, make
or destroy heat energy – it
simply moves it. It works like
your refrigerator; only in
reverse. It takes the heat from
the surrounding air, compresses
it, and transfers it into the water
stored in the tank. By-products
of this heat pump are cold air
and condensation.
Fan and Filter
(8 & 9)
EMB-Papst, Inc.
1400 – 2200 RPM
240 V, 1 phase, 60 Hz
Sealed ball bearing
<49 db
Filter must be cleaned
periodically.
ECO, upper
thermistor and upper
heating element
(3 & 4)
These are 2000 watt, 240 volt
stainless steel heating elements.
The thermostat (thermistor) is
an electronic resistance device.
The ECO will trip at @ 1700F
if the water inside the tank gets
too hot.
Lower thermistor and
lower heating element
(5)
These are 2000 watt, 240 volt
stainless steel heating elements.
The thermostat (thermistor) is
an electronic resistance device.

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Water pump
(7)
240V, 1 phase, 60 Hz
Taco, Inc.
1/40 HP; 3250 RPM
125 PSI max
When heating water, the pump
cycles the cooler water from the
bottom of the tank and through
the heat exchanger to maximize
heating and efficiency.
Heat Exchanger
(not repairable)
Packless Industries
650 PSI refrigerant working
pressure
Sealed and self contained heat
exchanger that uses the R410a
refrigerant to heat the water in the
tank.
Compressor
240V, 1 phase, 60 Hz
Mitsubishi Electric
(Siam Compressor
Industry)
9,383 BTU/HR
(nominal)
5.8 amps (rated load)
(not repairable)
The compressor moves the R410a
refrigerant around the heating
loop. The compressor serves two
purposes:
•The first is to circulate the
refrigerant liquid through the
circuit like a pump.
•The other is to compress and
raise the pressure and
temperature of the refrigerant
vapor so that it can be used in
the heat exchange process.
Transformer
(11)
The transformer takes incoming
240 VAC line voltage and steps
it down to 24 VAC for the
control board and other
components to use.

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Capacitor
(12)
A heat pump capacitor is used
to give the compressor motor an
electrical "boost" when a
working load is placed on the
unit. It makes the unit easier to
start.
Relays (13)
•Compressor Relay
•Upper Heating
Element Relay
•Lower Heating
Element Relay
Relays allow power to be
transferred to another location
or part.
In the case of the HPWH, the
relays are used to control the
routing of voltage to the heating
elements and compressor
during the various operating
modes.
Filter / Dryer
(not repairable)
The filter / dryer removes any
water vapor and moisture from
the R410a refrigerant line.
Ambient Air
Thermistor
(15)
Therm-o-disc
10,000 ohms thermistor
Located on fan cover housing
beneath filter
Measures the temperature of the
surrounding air where the water
heater is installed.

Heat Pump Water Heater
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Evaporator
Thermistor
(16)
Therm-o-disc
10,000 ohms thermistor
Measures the temperature of the
evaporator gasses.
Discharge Thermistor
(17)
Therm-o-disc
10,000 ohms thermistor
Measures the temperature of the
discharge gasses.
This thermister is difficult to
see. It is on top of the
compressor.
Suction Thermistor
(18)
Therm-o-disc
10,000 ohms thermistor
Measures the temperature of the
suction gasses.
Water Out Thermistor
(19)
Therm-o-disc
10,000 ohms thermistor
Measures the temperature of the
heated water from the heat
exchanger to the water pump.

Heat Pump Water Heater
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Charging and
pressure check valves
(not serviceable)
Valves use to charge and check
the pressure in the heat pump.
These valves are not normal
service ports and require special
HVAC licensing and refrigerant
collection equipment.
Electronic Expansion
Valve
(not repairable)
Fujikoki Corp.
Valve that is part of the
refrigerant system. It allows the
R410a refrigerant to change
from a high pressure gas to a
low pressure gas.
Condensation Drain
(user installed drain
line)
The heat pump will create a
liquid called condensation. This
is the same condensation you
find on the outside of a cold
soda can. This condensation
must be discharged outside the
home; and may be governed by
a local code. Notice the ¾”
NPT drain and the ½” nipple
drain.
Electrical Connection
Primary hook up for the
incoming 240 VAC line voltage
to the water heater.
Ground

Heat Pump Water Heater
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Tools
You will need to following tools to work on the Heat Pump Water Heater:
•¼” nut driver (magnetic would be best)
•#2 phillips
•Adjustable wrench
•Multimeter – capable of 120/240 volts readings and Ohms resistance
•1 ½” element wrench
•Torx #20 screwdriver
Error Code LED
Light
This LED will blink when there
is a problem with the water
heater.
Circuit Board
(10)
The circuit board controls all
the electrical and temperature
sensing inputs for the heat
pump water heater. Connections
only go one way and are unique
to each connection port.

Heat Pump Water Heater
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Operational Modes
Energy Saver Mode
This mode will provide functional control operation
resulting in water heater performance that meets Energy
Star requirements; FHR (First Hour Rating) – exceeding the
minimum of 50 GPH (Gallons per Hour) with 62 GPH and
a minimum EF (Energy Factor) of 2.0. As a result,
compressor operation will be maximized and use of electric
heat will be minimized.
Normal Mode
This mode will maximize the performance of the water
heater while still providing good energy savings. This
mode provides a minimum FHR of 72 GPH at @ EF 1.5.
Primary goal is to maintain water heater performance that
meets or exceeds a comparable electric water heater.
Figure 2 – User Control
Electric Heat Only
This mode is utilized in conjunction with Normal, High, and Vacation modes. In this mode
compressor operation will not be allowed and only the auxiliary electric heat will be allowed.
Temperature set points noted with each of the modes will be used to turn the auxiliary electric
heat on as required.
This mode can only be utilized on a short term basis. Currently, this mode will be allowed for a
period of 2 weeks. After this time period, the water heater will attempt to revert to the Normal
Mode to save energy.
Temperature Settings
Normal - Tank water temperature will be maintained at @120-124º F. Compressor operation
will be allowed whenever the tank temperature at the lower heating element location falls to
@105º F or below.
High - Tank water temperature will be maintained at @132º F. Compressor operation will be
allowed whenever the tank temperature at the lower heating element falls to @110ºF or below.
Vacation - Tank temperature will be maintained at @ 90º F. Compressor operation will be
allowed whenever the tank temperature at the lower heating element falls to @80ºF or below.

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Water Pump Flow Rates
Water pump operation will be allowed whenever the compressor or
electric heat is operational. The basic water pump motor will be a
single speed 240 volt AC motor. Water pump speed will be controlled
via the control board based on Triac motor voltage control. (Triacs
are widely used in AC power control applications. They are able to
switch high voltages and high levels of current, and over both parts of
an AC waveform. This makes triac circuits ideal for use in a variety of
applications where power switching is needed.)
The triac control will output full voltage for approximately 2 seconds to allow motor start-up
before the voltage to the motor is reduced. During compressor operation the water pump will
utilize at least two (2) stages of control. A low pumping rate (about 1 GPM) will be used when
the measured tank water temperature is 110º F or below or when the electric heat is operational.
A high pumping rate (about 3 GPM) will be used at all other tank water temperature conditions.
The water pump will remain energized for 30 seconds once the compressor is de-energized to
allow the residual hot water in the heat exchanger to be returned to the water tank.
Evaporator Fan Speed
The default fan speed is low. Low fan speed is obtained by power output to two fan leads (the
3rd lead is common). High speed operation is obtained by de-energizing the low speed fan lead.
Operational Safety Controls – all Modes
The following controls are utilized to provide reliable heat pump operation for all operational
Modes:
•Thermistors will measure temperatures of both water and pressurized refrigerants during
the water heater cycle. For the first 90 seconds no operational control will be polled for
temperature values to prevent false reporting.
•Compressor has an anti-short cycle timer of 120 seconds. If the compressor is shutdown
for any reason, it will not be able to restart for 120 seconds.
•If the compressor suction temperature is below 37ºF, following the appropriate delays at
start-up or anytime thereafter, compressor operation is stopped. This will prevent coil
freeze-up.
•If compressor operation is stopped 3 times for suction temperatures below 37ºF,
compressor operation will be terminated for that run cycle. Once the run cycle is
terminated electric heat will be used to fulfill the water heating requirement. Compressor
operation will again be allowed.
•If the compressor discharge temperature rises to 195ºF or higher, compressor operation is
terminated. Should this occur 3 times during a run cycle, compressor operation will be
terminated for that run cycle and electric heat will fulfill the operational requirements.

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Sequence of Operations
Energy Saver Mode
Under no circumstances will the compressor and lower electric heating element
be allowed to operate at the same time.
Start Sequence
1. If lower tank thermostat is less than 70ºF and upper tank thermostat is less than 75ºF, the
water pump and both elements are energized until the lower tank thermostat is 80ºF. This
Pre-Warm mode prevents the compressor system from experiencing excessively low
discharge pressure.
2. Compressor then starts as required when tank temperatures greater than 80ºF.
3. Evaporator fan starts – low speed.
4. Water pump starts and operates as required by tank temperature.
5. Upper heating element will remain off during the start sequence.
6. For the first 90 seconds no operational control will be polled for temperature values.
7. After 90 seconds of operation -
a. If ST (suction temperature) is below 47ºF, the evaporator fan is adjusted to high
speed operation and an additional 90 second delay is started. ST is not polled
until after the additional delay.
b. AS (ambient temperature) and WT (water temperature) leaving the condenser are
polled. If AS is less than 40ºF but not greater than 120ºF and WT is less than
132ºF, compressor operation continues. If not, lower electric heating element
operation is allowed.
Run Sequence
1. Fan speed will be held at the value determined during the Start Sequence.
2. Water pump will modulate speed as required.
3. Compressor operation continues until lower tank thermostat or condenser water
temperature limits are reached.
4. The upper electric heating element operation is locked out during the first 45 minutes of
each compressor run cycle.
5. The lower electric heating element operation is locked out while the compressor and/or
the upper heating element are operating in Energy Save Mode.
6. Lower electric heating element operation is allowed whenever compressor and upper
heating element operation is no longer required and the lower tank thermostat remains to
be satisfied.
7. If compressor is not utilized, evaporator fan will be de-energized.
8. Compressor, upper electric heating element, and lower electric heating element will
deenergize as operational temperatures are reached.

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Normal Mode
Under no circumstances will the compressor and lower electric heating element
be allowed to operate at the same time.
Start Sequence
1. If lower tank thermostat is less than 70ºF and
upper tank thermostat is less than 75ºF, the water
pump and both elements are energized until
lower tank thermostat is 80ºF. This Pre-Warm
mode prevents the compressor system from
experiencing excessively low discharge pressure.
2. Compressor then starts as required by tank
temperatures greater than 80ºF.
3. Evaporator fan start – low speed.
4. Water pump starts and operates as required by
tank temperature. Figure 3 – Operating Modes
5. Upper heating element will remain off during the start sequence.
6. For the first 90 seconds no operational control will be polled for temperature values
7. After 90 seconds of operation:
a. If ST (suction temperature) is below 47ºF, the evaporator fan is adjusted to high
speed operation and an additional 90 second delay is started. ST is not polled
until after the additional delay.
b. AS, ambient temperature and WT, water temperature leaving the condenser are
polled. If AS is less than 40ºF but not greater than 120ºF and WT is less than
133ºF, compressor operation continues. If not, lower electric heating element
operation is allowed.
Run Sequence
1. Fan speed will be held at the value determined during the Start Sequence.
2. Water pump will modulate speed as required.
3. Compressor operation continues until lower tank thermostat or condenser water
temperature limits are reached.
4. The upper electric heating element operation is locked out during the first 30 minutes of
each compressor run cycle.
5. Afterwards, the upper electric heating element is operated as long as compressor
operation is permitted. This heater will continue operation until the upper thermostat
temperature limits are reached.
6. The lower electric heating element operation is locked out while the compressor and/or
the upper heating element are operating in Normal Mode.
7. Lower electric heating element operation is allowed whenever compressor and upper
heating element operation is no longer required and the lower tank thermostat remains to
be satisfied.
8. If compressor is not utilized, evaporator fan will be de-energized
9. Compressor, upper electric heating element, and lower electric heating element will
deenergize as operational temperatures are reached

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Electrical Heat Only Mode
This operational sequence is the same as the sequence for the Energy Saver and Normal Modes
except:
1.Compressor operation is not allowed.
2.Evaporator fan is de-energized and remains de-
energized.
3.Start sequence is not employed.
4.Water pump is set to low flow rate and remains in this
position. Water pump is energized whenever heat is
required to maintain the lower tank thermostat settings.
5.Electric heating element is cycled as required by the
Normal/High/Vacation mode temperature settings.
6.This operating mode is maintained for a maximum of
2 weeks or 336 hours. After this time period, the water
heater is returned to NORMAL operation.
Here is how the heating element electrical system works:
1.Always 240V between ECO 1 & 3 (even in heat pump modes)
2.Always 240V between ECO 2 & 4 (if ECO is not tripped)
3.Always 120V at blue wire to each element
4.Orange wire from ECO goes back to RELAYS at wire nut
5.Control board energizes respective Upper or Lower relay
6.Relay moves 120V power back thru red wire (upper element)
7.Or brown wire (lower element)
8.Now have 240V between element wires
9.Heating element operates at 2000 watts
Figure 4 – Heating Element Electrical System

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16
Safety Functions of the Controls
ECO (Energy Cut Off)
The ECO switch functions as a high limit switch responsive
when the water temperature approaches 170° F. If the water
temperature inside the tank reaches 170° F, the ECO switch
(normally closed) will open. The controller will disable all
heating functions and will render the heater into an error
condition. Figure 5 – Energy Cut Off
Power Outages
The controls will automatically resume operations after power interruptions. Unit will return to
last operating mode set on user control.
Heat Pump and Compressor Operations
The electronic control has some safety measures to prevent damage to the refrigerant side of the
heat pump. It will prevent overheating and freeze up of the refrigerant part of the system.
Troubleshooting
Error Code LED Light
AN1 is red in color and is used to display diagnostic
codes. Flash rate is 0.33 seconds on, 0.33 seconds off
with 2.0 seconds off between flash codes. Flash codes
are as follows: Figure 6 – Error Code LED
•Steady On – After 120 second anti short cycle period; No fault present
•Steady Off - No power to control or control board fault
•1 Flash - Compressor off because Anti-short cycle Delay (normal operations)
•2 Flashes - Compressor off because Ambient temperature too high (>=1200F)
•3 Flashes - Compressor off because Discharge temperature fault (>= 1950F)
•4 Flashes - Compressor off because Suction temperature fault (<= 370F)
•5 Flashes - (Discharge temp - Suction temp) (<350F)
•6 Flashes - Compressor off because High Pressure switch open; or water pump does not
work
•7 Flashes - Compressor off because water temperature from heat exchanger is too
high(>= 1320F)
•8 Flashes - One or more sensors (not tank temp related) open/short; or missing model
plug
•9 Flashes – Open/short in the tank temperature sensing circuit

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Troubleshooting the Heat Pump Components
Trouble Probable Cause Remedy
Compressor will
not run ON/Off switch OFF. Wiring improper or loose.
Circuit breaker tripped.
Low voltage to unit.
Compressor motor has a wiring
open or shorted.
Internal mechanical trouble in
compressor
Turn unit ON.
Check wiring against diagram.
Reset breaker.
Check voltage.
Replace water heater.
Replace water heater.
Compressor starts
and runs, or short
cycles.
Low voltage to unit.
Circuit breaker tripped.
Capacitor defective.
Excessive discharge temperature.
Suction temperature too high.
Compressor too hot-return gas too
hot.
Compressor motor has a wiring
open or shorted.
Internal mechanical trouble in
compressor
Check voltage.
Reset breaker.
Check and replace capacitor.
Determine reason and correct.
Determine reason and correct.
Check ventilation and fan/fan filter
Replace water heater.
Replace water heater.
Unit runs but short
cycles on Thermostat defective. Refrigerant line leaking.
Restriction in expansion valve
Check tank thermistors.
Replace water heater.
Replace water heater.
Unit operates long
or continuously Dirty air filter. Evaporator coil iced.
Dirty heat exchanger.
Clean or replace.
Determine reason and correct.
Clean heat exchanger coils
Suction line frosted
or sweating Expansion valve damaged Evaporator fan not running. Replace water heater. Determine reason and correct.
Unit noisy Loose parts or mountings.
Tubing rattling.
Bent fan blade causing vibration.
Fan motor bearings worn.
Find and tighten.
Insulate and buffer.
Replace fan motor
Replace fan motor.
N O T E S
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Troubleshooting Component Parts
Upper or Lower Heating Elements
How to check for an open element
An open element is a condition where the nichrome filament wire is broken somewhere on the
inside of the heating element and you cannot tell by a visual inspection. The electrical
connection is open and the electrical current cannot flow along the path of the filament.
1. Turn off the power to the water heater. Check for the presence of power with a
multimeter.
2. Remove both wires from both screw terminals of the heating element.
3. Place test probes of the OHM meter on both screw terminals. If the OHM meter does
not register a resistance, the element is open and should be replaced. Ideal resistance is @ 21 to
28 OHMs.
How to check for a grounded element
4. With the power remaining off place one test probe on either of the screw terminals
and the other test probe to the steel inner tank. If the OHM meter registers any resistance, the
element is grounded and should be replaced.
Capacitor
The capacitor boosts power to help the compressor start and run.
1. Measure for 240VAC on the red wire to the capacitor and the black
wire on the compressor relay.
2. Measure between 352 to 388VAC on the red wire to the capacitor and
the purple wire to the compressor. The capacitor is rated at 370 VAC
±5%.
3. Replace capacitor if defective. Figure 7 - Capacitor
Transformer
The transformer supplies the power to operate the control
board.
1. Measure for line voltage (240VAC) on the black and
red wires to the transformer.
2. Measure for 24 VAC on the other side at the red and
brown wires.
3. Make sure red and black 24V wires are connected to
the board.
4. Replace transformer if defective. Figure 8 – Transformer

Heat Pump Water Heater
19
Thermistors (ambient, suction, discharge, water out, evaporator,
upper tank and lower tank)
There are seven (7) thermistors on the HPWH. Each one uses a standard 10,000 ohms resistor.
By measuring the resistance of the thermistor from the control board, you can determine if the
thermistor is working properly.
See chart for resistance values of the thermistors. They are all 10,000 ohm
based thermistors, so this chart will work for any of the thermistors on the
HPWH.
1. Turn the power off to the HPWH. You will expose yourself to a
potential shock when you reach for a thermistor.
2. Open the upper cover that surrounds the heat pump portion of the
water heater.
3. Locate the circuit board
4. Locate the specific thermistor you want to test.
5. Remove the thermistor from the circuit board.
6. Measure ohms resistance between the two wires of the thermistor.
7. Compare this resistance to the chart on the last page and determine
the temperature. Figure 9 – Thermistor Connections
Fan Assembly
1. Cycle the water heater to Energy Saver or Normal mode. The fan does not work in
electric heat only mode.
2. You should hear the fan running.
3. Locate the fan motor Molex on the circuit
board.
4. Measure for 240 volts AC between the
black and blue wires.
5. If you have voltage, and the fan is not
running, replace the fan. If you do not have
voltage, replace the circuit board. Figure 10– Fan Motor and Water Pump Connections
Water Pump
1. Cycle to water heater to Energy Saver or Normal mode. The water pump works in all
operating modes mode.
2. You may hear the pump running or feel the pump vibrate.
3. Locate the water pump Molex on the circuit board.
4. Measure for @160 – 240 volts AC between the black and blue wires.
5. If you have voltage, replace the water pump. If you do not have voltage, replace the
circuit board.