PrecisionTemp RV500 & ShowerMate Water Heater Service Manual For information, contact: PrecisionTemp,Inc. 11 Sunnybrook Dr. Cincinnati, Ohio 45237 Phone: (800)934-9690 Fax: (513)641-0733 www.precisiontemp.
PrecisionTemp Authorized RV500 Service Schedule The following figures are standard time requirements allowed for repair or replacement of components. Warranty service charges time exceeding these standards will not be paid unless prior approval is obtained from PrecisionTemp. Service charges will be paid in tenths of an hour (six minute increments) General Trouble-Shooting ………… Maximum of 30 minutes (0.
CONTENTS Section 1. Definition of Terms Section 2. Description of Operation Section 3. Trouble-Shooting the RV500 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.
Section 1. Definition of Terms AutoCal – A procedure by which the microprocessor in the heater accesses a stored calibration table to convert gas flow to voltage to control the gas valve. DSI (Direct Spark Ignition) – The circuit board that controls the ignition process. Once supplied with 12 vdc by the main circuit board, it opens the gas solenoid, sparks the igniter, and senses the flame. Also, during operation it continues to monitor the flame and will fire the igniter if flame rectification is lost.
Section 2. Description of Operation RV500 With gas and power supplied and no water flow, the RV500 will appear dormant except for the green LED flashing once each second. However, the microprocessor in the RV500 is actively monitoring the three temperature sensors, the set temperature request, and the water flow each half second in anticipation of a request for hot water. When a hot water faucet is opened and flow is 0.
Section 2.1 Description of Operation ShowerMate Note: The next 8 steps take place in 3-5 seconds. The flow meter senses the water flow & sends a flow signal to the green control board. The green control board sends 12 VDC through the orange wire to the pressure differential switch and on to the black relay that powers the power vent blower. The relay closes the 12VDC contacts to start the blower.
Section 3. Trouble-Shooting the RV500 3.1 Water Leak Identify the location. If a compression fitting or standard NPT fitting is the source, be sure the fitting is fully tightened. CAUTION: 1) Use two wrenches so that no force is transferred to other parts, and 2) over-tightening fitting can damage the unit. If tightening the compression fitting does not stop the leak, replace the flowmeter and tube assembly.
6. 7. Examine the micro-controller EL 9049 (see figure -4). Be sure that all pins are in the socket and none appear bent (use thumb to gently press on the chip). If the problem persists then change board 1841-RV. Refer to SM500-01 for the change procedure. 3.4 Green LED flashes, but no ignition attempt (no igniter, no gas) 1. Is the water ON and is the flow out of the faucet at least 0.5 gallons per minute (2.5 minutes to fill 1 gallon)? Flow must be greater than 0.5 GPM for the unit to turn on. 2.
6. Replace the gas solenoid 1073 per SM500-13. 7. Replace the modulating valve 1076 per SM500-14. 3.6 Green LED flashes, but no ignition (no igniter sparks, no gas flow, no gas odor) 1. Check that the ignition wire 1412 is connected to the igniter and then check the wire for continuity. 2. With gas OFF, check if the igniter is sparking to the burner (see figure -3). If not, find where the igniter is sparking.
7. The RV500 will not increase the flame above minimum until a flameproof signal is sent to the circuit board by grounding the red lead attached to the spade connector on the DSI board. You can do this manually by touching the metal portion of the red wire to the RV500 steel case. The flame should increase. 8. Check thermisters per the section 4.5 ‘T-in, T-mid, T-out Thermister and T-set Readout’. 9.
5. Is unit changing between min burn and max burn? If yes, run AutoCal per SM500-15. 3.9 During a ‘Navy’ style shower water is cold for a short time after turning off and then back on 1. When water flow is turned off the RV500 will also turn off. Turning the water on again will result in a few seconds of over-heated water and then a few seconds of cold water. Our software minimizes the duration of the cold water, but it takes about three seconds to sense the flow and ignite the burner.
A cold water crossover occurs when the cold water is connected to the hot water line and cold water is allowed to enter the hot water line between the water heater and the point of use (see figure -6). The places to look for this happening are outside wash down boxes or showers, water heater bypass kits, showers with a shutoff on the shower head, washing machines, dishwashers, and in the plumbing to water using appliances (usually in parallel instead of in series).
head of air leaving nothing for the water to compress against, leaving the system as if no accumulator tank had been installed. A good accumulator tank will smooth the pulses and make the diaphragm pump a stream as smooth as if it were on city water. 4.5 T-in, T-mid, T-out Thermister and T-set readout If the red LED is flashing, turn power OFF for 5 seconds and then turn power ON? If the red LED is flashing, there is a potential problem with a thermister.
thermister cable 1329 for continuity on the two yellow wires. If either wire shows a break, replace the cable 1329. Otherwise, replace the T-mid thermister 2008 per SM500-08. Single Red flash Indicates that the T-out thermister has failed. The heater will substitute a calculated (model) T-out, based on T-mid, and continue to operate. At a constant water flow the temperature output will remain constant. Over the operating water flow range, normally, this approximation will be within 3F.
Water Flow - gpm 4 Exceeds Range 3 2 Operating Range 1 Below Range 0 20 30 40 50 60 T-out – T-in, ºF Figure 1.
12 VDC Cold Gas Hot Figure 2.
1434 Burner/Heat Exchanger 2008 2086 1588 1437 1330 1073 1076 1375 Front View 1315 1076 2008 1315 1434 1436 1437 2086 1330 1375 1073 1436 Modulating Gas Valve, LPG Heat Exchanger Core Temperature Sensor Burner Assembly Burner/Heat Exchanger Assembly Inlet Temperature Sensor Outlet Temperature Sensor ECO Flow Meter Pressure Relief Valve LPG Gas Solenoid Figure 3.
Figure 5.
Electronic Control Board 200-14 Brown Test Point 1076 1331 Black Test Point Micro processor ACAL Jumper JMP 1 Jumper 1333 1330 Relay Orange Test Point Alarm Connector (not used) 1329 Green LED Red LED Yellow Test Point T_set Pot Blue Test Point 1076 1329 1330 1331 1333 Alarm ACAL Jumper JMP 1 Jumper Orange Test Point Yellow Test Point Blue Test Point Brown Test Point Black Test Point Modulating Gas Valve Connection Thermister Wiring Harness Connector Flowmeter Connection Power Supply Wiring Harn
Normal operation Cold in Water Cold in open open closed closed Hot out Shower head with shut off Cold water crossover Water Cold in open Cold in open open open Hot out Shower head with shut off closed Example of a “cold water crossover” Hot water Cold water Figure 6. Cold Water Bypass T-mid Thermister Pipe Fitting This end into Heat Exchanger Ferrule Yellow Wires Figure 7.
Spark gap to be 0.125 1411 1076 1411 1315 Manifold Pressure Tap 1076 Modulating Gas Valve LPG 1315 Burner Assembly 1411 Igniter Figure 8.
RV500 Wiring Schematic 2004 & prior years 06/2010
06/2010
Model: RV500-F-L / RV501-F-L Schematic RV500 2004 - present SM500-01 Circuit Control Board Replacement Other service documents required: SM500-15 Automatic calibration (AutoCal) SM500-16 Testing the RV500 Tools Required: Needle-nose pliers 1. Turn off power. Disconnect all electrical connectors at the circuit board. 2. Remove the circuit board. A needle-nose plier can be used to remove the circuit board standoffs. 3.
4. Install the new board with the LEDs located at the front of the drawer. Reconnect all connectors to the board. CAUTION: there are two two-pin connectors. Be sure that the power supply connector (red and black wire) goes to upper left corner and the valve connector (white and black wire) goes to upper right (see figure -4). 5. Put the LED holders in. 6. The set temperature is already at 122F. Refer to manual if a further adjustment is desired. 7. You must run AutoCal to complete the installation.
2. Remove the electronics drawer. To remove the board requires a ¼” socket or a 5/16” wrench. 3. Install the new DSI board and re-attach the wire harnesses. Be sure to route the ignition harness separate from the other control harnesses. Kit Parts List: 3158 3166 Figures: none Model: Direct Spark Ignition (DSI) board DSI Mounting Bracket RV500-F-L / RV501-F-L SM500-03 Electrical Drawer Assembly Change Other service documents required: SM500-16 Testing the RV500 Tools Required: none 1. Turn power OFF.
3. Slide the drawer forward to reveal the two circuit boards AS 1312 and EB 1378. Wire harnesses will not permit the drawer to be removed. Disconnect the one connection to EB 1378 and the five (5) connections to AS 1312. All electrical connectors in the drawer should now be disconnected and the drawer can slide out of the guides. 4. Route the wire harnesses through the grommets of the new drawer. Be sure to route the ignition harness separate from the other control harnesses.
3. Note: Model 500 with serial numbers prior to 97-07-xxxx. Remove the four sheetmetal screws located two on each side of the case. The head of the screw is accessed from the outside of the case. If the screws are not accessible then the case must be pulled from the RV sufficiently to access the screws. Note: Model 500 with serial numbers after 97-07-xxxx and ALL MODEL 501 Using a Phillips screwdriver remove the 8-32 screw located at the middle rear of the hood (see figure -3).
7/8 open end wrench 4. Turn power OFF, water OFF, and gas OFF. 5. Disconnect the gas line, water inlet, and water outlet. 6. Remove the hood assembly per SM500-04. 7. Remove the two 8-32 screws on the sides of the burner bracket using the ¼” socket and 9mm open end wrench. Refer to figure -3. 8. Slide the heat exchanger / burner assembly 1434 forward and out of the case. 9. Remove the thermister cable 1329 and DSI cable 1829. 10.
13. Turn power OFF, water OFF, and gas OFF. 14. Remove the hood assembly per SM500-04. 15. Remove the heat exchanger / burner assembly 1434 per SM500-05. 16. Remove the two 8-32 machine nuts from the left side of the heat exchanger that attach the heat exchanger assembly 1435 from the burner assembly 1315. 17. Turn the new heat exchanger assembly 1435 upside down and place on a flat, level table.
1. Remove the wire ties, metal tape, and old thermister. Clean off the old heat sink and be sure copper is wiped clean. Note : T-in thermistor position changed on newer models. Current location is on the same tube forward of the PRV where the pipe makes a 90 degree vertical at the copper heat exchanger. 2. Apply heat sink compound to copper tube. 3. Place the thermister into the heat sink compound. Wrap metal tape around the tube and thermister. 4. Take the two wire ties.
2. Place the fitting and the ferrule on the thermister as shown in figure -7. 3. Insert the end of the thermister without electrical leads into the heat exchanger until the heat shrink (black) on the thermister touches the fitting and tighten the fitting finger-tight. Wiggle to locate center. The final tightening should be done using two wrenches as described in step 1. 4. Check the resistance across the thermister leads. Under room temperature conditions the value should be between 700 - 1100 ohms.
5. Take the two wire ties. One goes around the wires as a strain relief. The other goes near the thermister (about 3/8” away from the head) to hold the thermister against the tube. CAUTION: 1) Do not place the tie wrap over the thermister tip as this may crack the thermister, and 2) Do not over-tighten the wire ties. 6. Check the resistance across the thermister leads. Under room temperature conditions the value should be between 700 - 1100 ohms.
outside of the heat exchanger and the heat exchanger other side is resting on the ledge of the burner assembly. See figure -8. 6. Be sure the table is level. Place a level on the burner bracket. Adjust the burner assembly until it is level and mark the heat exchanger through the two mounting holes in the burner bracket. 7. Remove the burner assembly and drill ¼” holes at the two marked holes on the heat exchanger. 8. Again place the burner on the heat exchanger.
3. Remove the heat exchanger / burner assembly 1434 per SM500-05. 4. Separate the heat exchanger assembly 1435 and burner assembly 1315 per SM500-06 or SM500-10. 5. Remove the one screw 1409 that attaches the igniter bracket 1410 and electrode 1411. 6. Replace the electrode and re-assemble onto the burner. 7. Using the 1/8” drill bit as a gage, bend the end of the electrode with the pliers until it is centered over the burner blade and 1/8” above the burner (see figure -8). 8.
14. You must run AutoCal to complete the installation. Refer to SM500-15. 15. Check the unit for normal operation per SM500-16 ‘Testing the RV500’ Kit Parts List: 1330 Flowmeter assembly Figures: Figure-3 Figure-4 Model: Frontal View of RV500 with Door Removed View of Electronic Drawer RV500-F-L / RV501-F-L SM500-13 Gas Solenoid Replacement Other service documents required: SM500-16 Testing the RV500 Tools Required: Basin wrench or crow foot wrench Adjustable wrench 1.
6. USE AGA-APPROVED SEALANT ON ALL GAS THREAD CONNECTIONS. Assemble the flare elbow into the new gas solenoid. 7. Screw the gas solenoid 1073 onto the end of the piping in the case. Continue to tighten until the spade connections are to the rear of the unit. 8. Attach the four spade connections. Looking from the front, the two blue wires attach on the left and the two white wires on the right. 9. Connect the gas supply and test for leaks. 10.
5. Use the 7/8 wrench on the modulating valve hex to unscrew the valve and pipe nipple from the burner manifold. Then separate the pipe nipple from the valve. 6. To replace the coil only remove the C clip from the modulating valve tube, slide the coil off and install replacement coil. Make sure the direction arrow is pointed toward the manifold. Reinstall C clip. 7. USE AGA-APPROVED SEALANT ON ALL GAS THREAD CONNECTIONS. Assemble the pipe unto the new modulating valve and into the manifold.
continuing. Over the next 8 minutes the unit will be increasing the gas flow to calibrate the valve. The unit will run the test by itself and only requires monitoring for safety. When the test is ended the red LED will flash. 13. Turn power OFF and water can be turned off. 14. Replace the jumper on the board. 15. Turn on power. 16. Check the unit for normal operation (refer to SM500-16 ‘Testing the RV500’). If all operation appears normal the procedure is complete.
2. On circuit board set T-set (blue test connector) to 2.0 volts (120F). 3. Set water flow 0.5 gpm (gas OFF) and verify the DSI function: 2.5 sec fire, 3.0 sec purge, 2.5 sec fire, lockout. 4. Run AUTOCAL (SM500-15), if required. 5. Shutdown. Disconnect DSI flamesense feedback to board (see figure TS500-4) Modulating valve voltage = (0.0 vdc) Manifold pressure = (0.65 - 1.15 wci) Verify gas stays at min. 6. Fail T-mid thermister. Verify gas flow is shutoff. System lockout (red LED double flashing). 7.
1. Turn off the power supply and gas supply to the RV500. 2. Turn off main water supply. 3. Open all hot water taps. (Bathroom, kitchen, laundry, etc.) 4. Drain water from plumbing lines. 5. Open pressure relief valve to drain remaining water from the heat exchanger and flowmeter.
1329 2940 2028 2451 2984 1103 1703 1331 3189 3190 Thermistor Harness Pressure Switch ShowerMate only Relay ShowerMate only Exhaust Blower ShowerMate only 10vdc Voltage Regulator ShowerMate Modulating Valve Coil RV 500 Wind Fan Power supply harness RV500 Wiring Harness Assy. ShowerMate Wiring Harness Assy.
