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 1
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. 2
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. 3
Component Parts of the Heat Pump Water Heater Figure 1- HPWH Service Parts Part Name Description Picture This panel allows for user selection of water temperature and operating mode. User control (14) 4
Heat Pump (not repairable) Fan and Filter (8 & 9) 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. EMB-Papst, Inc. 1400 2200 RPM 240 V, 1 phase, 60 Hz Sealed ball bearing <49 db Filter must be cleaned periodically. These are 2000 watt, 240 volt stainless steel heating elements. ECO, upper thermistor and upper heating element (3 & 4) The thermostat (thermistor) is an electronic resistance device. The ECO will trip at @ 170 0 F if the water inside the tank gets too hot. These are 2000 watt, 240 volt stainless steel heating elements. Lower thermistor and lower heating element (5) The thermostat (thermistor) is an electronic resistance device. 5
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. Packless Industries 650 PSI refrigerant working pressure Heat Exchanger (not repairable) Compressor 240V, 1 phase, 60 Hz Mitsubishi Electric (Siam Compressor Industry) 9,383 BTU/HR (nominal) 5.8 amps (rated load) (not repairable) Transformer (11) Sealed and self contained heat exchanger that uses the R410a refrigerant to heat the water in the tank. 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. The transformer takes incoming 240 VAC line voltage and steps it down to 24 VAC for the control board and other components to use. 6
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. The filter / dryer removes any water vapor and moisture from the R410a refrigerant line. Filter / Dryer (not repairable) Therm-o-disc 10,000 ohms thermistor Ambient Air Thermistor (15) Located on fan cover housing beneath filter Measures the temperature of the surrounding air where the water heater is installed. 7
Therm-o-disc 10,000 ohms thermistor Evaporator Thermistor (16) Measures the temperature of the evaporator gasses. Therm-o-disc 10,000 ohms thermistor Discharge Thermistor (17) Measures the temperature of the discharge gasses. This thermister is difficult to see. It is on top of the compressor. Therm-o-disc 10,000 ohms thermistor Suction Thermistor (18) Measures the temperature of the suction gasses. Therm-o-disc 10,000 ohms thermistor Water Out Thermistor (19) Measures the temperature of the heated water from the heat exchanger to the water pump. 8
Valves use to charge and check the pressure in the heat pump. Charging and pressure check valves (not serviceable) These valves are not normal service ports and require special HVAC licensing and refrigerant collection equipment. Fujikoki Corp. Electronic Expansion Valve (not repairable) 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. Primary hook up for the incoming 240 VAC line voltage to the water heater. Electrical Connection Ground 9
This LED will blink when there is a problem with the water heater. Error Code LED Light 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. 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 10
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. 11
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 3 rd 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. 12
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. 13
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 14
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 deenergized. 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 15
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 (>=120 0 F) 3 Flashes - Compressor off because Discharge temperature fault (>= 195 0 F) 4 Flashes - Compressor off because Suction temperature fault (<= 37 0 F) 5 Flashes - (Discharge temp - Suction temp) (<35 0 F) 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(>= 132 0 F) 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 16
Troubleshooting the Heat Pump Components Trouble Probable Cause Remedy 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 Replace water heater. compressor Compressor will not run Compressor starts and runs, or short cycles. Unit runs but short cycles on Unit operates long or continuously Suction line frosted or sweating Unit noisy 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 Thermostat defective. Refrigerant line leaking. Restriction in expansion valve Dirty air filter. Evaporator coil iced. Dirty heat exchanger. Expansion valve damaged Evaporator fan not running. Loose parts or mountings. Tubing rattling. Bent fan blade causing vibration. Fan motor bearings worn. N O T E S Turn unit ON. Check wiring against diagram. Reset breaker. Check voltage. Replace water heater. 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. Check tank thermistors. Replace water heater. Replace water heater. Clean or replace. Determine reason and correct. Clean heat exchanger coils Replace water heater. Determine reason and correct. Find and tighten. Insulate and buffer. Replace fan motor Replace fan motor. 17
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 18
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. 19
Circuit Board The circuit board may become damaged. IF the board has power, then the board must work. In the event nothing happens when you attempt to turn on the HPWH, then check in sequence: Circuit breaker Local ON/OFF switch User Key Pad for Normal or Energy Saver Mode (you will see a green led light) Measure for 240 VAC at the L1B (black wire) and the L2B (red wire) on the control board. If you have the voltage present, then replace the circuit board. If you do not have voltage present, then the problem lies in the power supplied to the HPWH. IF the board has power, the AN1 LED will be steady on after two minutes; or blinking during the anti-short cycle phase. Figure 11 Power Check Relay Switch There are three relay switches on the HPWH. The purpose of the relay switch is to send power and control certain component parts. With the control board, they control the compressor, upper heating element and lower heating element. The control board sends out the 240 volt signal thru the respective wires from the P7 connection: black for compressor; orange for upper heating element; blue for lower heating element. The control board knows when to send a signal based on 1. the mode selection (energy saver, normal or electric elements) and 2. the temperature sensing of the upper and lower tank thermistors Figure 12 - Relays The control sends the 240 volt signal to the relay. The relay receives the signal and activates the electromagnet (contactor). This closes the copper contacts at the Normal Open terminal connection of the relay and completes the 240 volt circuit. The completed 240 volt circuit energizes the upper element, lower element or compressor depending on the mode selection. 20
Once the tank sensors are satisfied, the control drops the signal to the relays; the electromagnet releases and the relay contacts open. Troubleshooting the relay is as simple as checking the mode and a demand for heat. IF the relays are getting 240V from P7, then they MUST work. You will have one or more of the following actions: Energy Saver and Normal Mode: The compressor is on (you can hear it) Heating Element Only Mode 240V at the upper heating element (measure with multimeter) 240V at the lower heating element (measure with multimeter) Disassembly and Repair Upper or Lower Heating Elements Heating elements in Rheem HPWH are screw in immersion type equipped with a one inch threaded pug. They can best be replaced with a standard 1 1/2 inch hex socket wrench. 1. Turn off the power to the water heater and remove access panels. 2. Turn off the cold water supply at the shut off valve. Open a hot water faucet or the T&P valve to relieve the pressure inside the tank. Open the drain valve at the bottom of the tank and drain water to below the level of the element. 3. Remove both wires from the element terminal screws. 4. With a 1 1/2 inch hex socket wrench, remove the element. Check the shoulders of the element seat on the tank and remove any remainder of the gasket material. 5. Install a new 2000 watt stainless steel heating element and gasket. Reconnect wires to the terminal screws. 6. Insure drain valve at the bottom of the tank is closed. Turn on the cold water supply and fill the tank. Purge all the air from the tank through the open faucet in step 2. 7. Close faucet, check for leaks and return power to the water heater. 8. Check thermostat for a safe temperature setting. Upper ECO & Thermistor or Lower Thermistor 1. Turn off power to the water heater and remove access panels. 2. Remove the four wires to the ECO. 3. Disconnect white Molex plug. 4. Pry the ECO and thermistor from the retaining bracket. 5. Replace in reverse order. Figure 13 ECO & Upper Thermistor 21
Capacitor 1. Turn off power to the water heater. 2. Using a flat blade and insulated screwdriver ground either the red or purple terminal to the water heater to discharge any residual power in the capacitor. 3. Using a flat blade screwdriver or ¼ inch nut driver, remove the two screws holding the capacitor strap. 4. Disconnect the wire leads one at a time and attach to new capacitor. 5. Secure replacement capacitor in place with the two screws and strap. 6. Return power to the water heater and check for safe operation. Relays 1. Turn off power to the water heater. 2. Using a flat blade screwdriver or ¼ inch nut driver, remove the two screws holding the relay. 3. Disconnect the wire leads one at a time and attach to new relay. 4. Secure replacement relay in place with the two screws 5. Return power to the water heater and check for safe operation. Figure 14 Replace Capacitor or Relays Transformer 1. Turn off power to the water heater. 2. Using a flat blade screwdriver or ¼ inch nut driver, remove the two screws holding the transformer. 3. Disconnect the wire leads one side at a time and attach to new transformer. 4. Secure replacement transformer in place with the two screws 5. Return power to the water heater and check for safe operation. Thermistors (ambient, suction, discharge, water out, evaporator, upper tank and lower tank) Turn off power to the HPWH. Replacing a thermistor amounts to following the wiring harness from the control board to the thermistors location. This is the easiest way to locate the thermistor. When found, remove the clamping bracket and thermistor. Replace with the new thermistor and route the Molex connector back to the control board. Restore power and check for safe operation. 22
Fan Assembly 1. Turn off power to the water heater and remove the fan filter. 2. Using a flat blade screwdriver or ¼ inch nut driver, remove the screws holding the fan cover. 3. Disconnect Ambient Air thermistor and fan Molex from board. 4. Place fan assembly cover on a work surface and remove the fan. 5. Install new fan. 6. Reconnect Ambient Air thermistor and fan Molex to board. 7. Reattached fan assembly cover to heat pump unit. 8. Reinstall fan filter. 9. Return power to the unit and check for safe operation. Figure 15 Replace Fan Assembly Water Pump 1. Turn off the power to the water heater. Check for the presence of power with a multimeter or test lamp. 2. Turn off the cold water supply at the shut off valve. Open a hot water faucet or the T&P valve to relieve the pressure inside the tank. Open the drain valve at the bottom of the tank and drain water to below the level of the element. 3. Disconnect the wiring harness to the water pump. 4. Remove the four Torx 20 screws from the pump. They may be some residual water leaking when you remove the pump. 5. Mount the new pump and new o-ring. Tighten the four Torx 20 screws. 6. Reconnect wiring harness. 7. Open the cold water isolation valve and allow the HPWH to re-fill with water. Purge the tank from the hot water faucet or T&P valve you opened. 8. Return power to the unit and check for safe operation. Figure 16 Replace Water Pump Circuit Board 1. Turn off power to the water heater. 2. Using a flat blade and insulated screwdriver ground either the red or purple terminal to the water heater to discharge any residual power in the capacitor. 3. Ground your body and remove the replacement board from the protective bag. 4. First, remove the model plug Molex from the old board and place on new board. This is the only loose plug that could get lost. 23
5. Disconnect all the Molex connections to the circuit board. The Molex connections only go one way and to its respective receiver. If you are in doubt, label the wires (or write on the Molex) as you remove them with the connector number from the board. This is especially important for the thermistors. 6. Press the plastic spring clips of the retainers at the four corners of the board. Remove the board and leave the spring clips on the water heater. 7. Replace board on the four spring clips 8. Reconnect all Molex connections. 9. Return power to the water heater and check for safe operation. Figure 17 Replace Circuit Board 24
Wiring Connection Diagram Figure 18 Wiring Diagram 25
Temperature to Resistance Thermistor Chart Cº Fº Resistance Cº Fº Resistance Cº Fº Resistance 0 32 32,654 33 91 7,096 67 153 1,943 1 34 34,367 34 93 6,806 68 154 1,876 2 36 32,654 35 95 6,530 69 156 1,813 3 37 31,030 36 97 6,266 70 158 1,752 4 39 29,498 37 99 6,014 71 160 1,693 5 41 28,052 38 100 5,774 72 162 1,637 6 43 26,686 39 102 5,546 73 163 1,582 7 45 25,396 40 104 5,327 74 165 1,530 8 46 24,171 41 106 5,117 75 167 1,480 9 48 23,013 42 108 4,918 76 169 1,431 10 50 21,913 43 109 4,727 77 171 1,385 11 52 20,883 44 111 4,544 78 172 1,340 12 54 19,903 45 113 4,370 79 174 1,297 13 55 18,972 46 115 4,203 80 176 1,255 14 57 18,090 47 117 4,042 81 178 1,215 15 59 17,255 48 118 3,889 82 180 1,177 16 61 16,464 49 120 3,743 83 181 1,140 17 63 15,714 50 122 3,603 84 183 1,104 16 61 15,000 51 124 3,469 85 185 1,070 17 63 14,323 52 126 3,340 86 187 1,037 18 64 13,681 53 127 3,217 87 189 1,005 19 66 13,071 54 129 3,099 88 190 974 20 68 12,493 55 131 2,986 89 192 944 21 70 11,942 56 133 2,878 90 194 915 22 72 11,418 57 135 2,774 91 196 889 23 73 10,921 58 136 2,675 92 198 861 24 75 10,449 59 138 2,579 93 199 836 25 77 10,000 60 140 2,488 94 201 811 26 79 9,571 61 142 2,400 95 203 787 27 81 9,164 62 144 2,315 96 205 764 28 82 8,776 63 145 2,235 97 207 742 29 84 8,407 64 147 2,157 98 208 721 30 86 8,056 65 149 2,083 99 210 700 31 88 7,720 66 151 2,011 100 212 680 32 90 7,401 Figure 19 Thermistor Resistance Chart 26
N O T E S 27