Service Bulletin EP-25 Models: AE115, AE125, RP17PT, RP27PT (prior to FD108) Comprehensive Troubleshooting Guide DANGER: ELECTRIC SHOCK ELECTRICITY IS EXTREMELY DANGEROUS. TAKE EXTRA PRECAUTIONS AND DISCONNECT THIS PRODUCT FROM THE ELECTRICAL SUPPLY BEFORE CLEANING, SERVICING OR REMOVING THE COVER. Step 1 – Document installation details Complete the “Building and Install” questionnaire. Step 2 – Water supply and water heater settings BOSCH ELECTRICAL APPLIANCES SHOULD ONLY BE SERVICED BY A TRAINED TECHNICIAN. Check temperature knob setting: 1. Make sure the temperature knob is set all the way clockwise as viewed from the bottom of the water heater. Tip: The temperature knob setting dictates the output water temperature: try testing the water temperature at several settings. Figure 1 Document results from each troubleshooting step prior to calling. Without this information documented, we cannot make a determination as to what is wrong with your water heater: this will delay a resolution. Introduction Who should perform the troubleshooting? Anyone who has the qualifications to work safely with 240VAC. If you do not possess the tools or the knowledge to work safely with 240VAC, contact a local professional. What does this troubleshooting guide cover? This guide covers every test we can advise you to perform on the location, installation, and water heater. With ALL the information from ALL the tests in this guide, it is possible to diagnose any water heater of this type to a point where we can advise a repair or cover warranty. Required tools: Adjustable wrench Gallon container Digital multi-meter Phillips head screwdriver Bottom of Heater 2. Verify flow rate 1. For Leaks: Complete Step 1 only and call Bosch Electric Technical Support 1-866-330-2729. You will need a description of the leak, its location and may be asked for digital pictures. Document your findings in the Building and Installation questionnaire. Using a graduated container (a ½ or 1 gallon container works well), time how long it takes to fill it with water from a hot water only faucet or shower. Calculate the flow rate by taking the size of the container and dividing it by the time it took then multiplying the answer by 60. This will yield a gpm result. 2 | EP-25 | AE115, AE125, RP17PT, RP27PT Example: Water collected (gallons) Time to fill (seconds) 2. 1. X 60 = gallons per minute Document your findings in the Building and Installation questionnaire. If flow rates were below 0.6 gpm on 17kW units and 0.8 gpm on 27kW units, check the inlet water screen: 1. Shut the water supply off to the water heater and open a hot water faucet to relieve the pressure. 2. Remove the cold water supply line from the bottom of the water heater. 3. Remove the inlet water screen from the cold water connection, inspect, and clean it as required. Keep water supply off to the water heater, isolating the hot water side of the system. Do not turn off the water supply to the whole house; only to the water heater. If you do not have an isolation valve on the water heater, you cannot perform this test. Flow rates below 0.6 gpm on 17kW units and 0.8 gpm on 27kW units, will not activate the water heater. Flow rates above 2.5 gpm on 17kW units may cause insufficiently warm water. Checking for plumbing crossovers: 2. Open ALL hot water taps and set all fixtures to hot only. 3. Allow some time (approx. 5 minutes) for water to stop running and pipes to drain. If pipes are drained you should be able to place hand over end of faucet and feel no pressure. 4. If any water continues to flow, you have found a crossover and one of the following conditions could exist and must be corrected: ― The most likely cause of this condition is that a mixing valve has an internal leak allowing cold water to mix with the hot. While this may not be causing the symptoms at your water heater, it will certainly affect the ability of the water heater to reach its maximum stated output and can cause activation issues and temperature fluctuations. Figure 2 ― While unlikely, a cold water pipe could be connected to a hot water pipe. If you have had some plumbing work done recently and the symptoms coincide with the work done, you may want to contact the person that did the work. Heater bottom 5. Close all fixtures and reopen water supply to the water heater. 6. Document your findings in the Building and Installation questionnaire. Step 3 – Visual inspection Visual Inspection 1. 4. Install the inlet screen and attach the water line in accordance with standard plumbing practices. Take care to not get any pipe sealant inside the unit. 5. Document your findings in the Building and Installation questionnaire. 2. Data subject to change without notice | Printed in the USA | BTC 722002306 C | 10.2013 Thoroughly inspect the water heater’s internal components. Note the following: ― Burn or scorch marks on the PCB ― Any signs of melted or damaged wires ― Cracks in plastic components ― Alignment of components ― Screw tightness Document your findings in the Water Heater questionnaire. Check the flow transducer (Fig. 3): 1. With the water running at least 1 gpm (gallon/minute), make sure the flow transducer is turning. Tip: Use a flashlight to illuminate the flow transducer and have someone turn the water on and off. Because the flow transducer spins so fast, it is more likely you will see the movement as it first begins to spin and as it stops spinning. 2. Document your findings in the Water Heater questionnaire. Bosch Thermotechnology Corp. EP-25 | AE115, AE125, RP17PT, RP27PT | 3 | Figure 5 Figure 3 27kW terminal block Supply 1 Supply S upply 2 Supply 3 To Supply 1 Flow Transducer Sup To Supply 2 Circuit Board To Supply 3 3 independent 40 amp double-pole circuit breakers Heater design may vary 3. Step 4 – Verify the power supply Figure 6 Check the power supply using an appropriate scale for 240 VAC. 1. Measure the incoming voltage: ― AE-115 / RP17PT have two readings (Fig. 4) ― AE-125 / RP27PT have three readings (Fig. 5) 2. Check the pairing of the incoming power connections by measuring the voltage of all combinations of L1 to L1 and L2 to L2. Voltage between any of these pairs (L1-L1 or L2L2), indicates an installation error and must be resolved by an electrician. Check that voltage is reaching the PCB by measuring the voltage between the blue and brown power connections on the board itself (Fig. 6). Figure 4 17kW terminal block Supply 1 S Supply upply 2 To Supply 1 To Supply Sup 2 4. Shut off the circuit breakers powering the appliance, lock them, and verify that there is no voltage at the unit. 5. Document your findings in the Water Heater questionnaire. 2 independent 40 amp double-pole circuit breakers Data subject to change without notice | Printed in the USA | BTC 722002306 C | 10.2013 Bosch Thermotechnology Corp. 4 | EP-25 | AE115, AE125, RP17PT, RP27PT Step 5 – Troubleshoot the element assemblies Verify that circuit breakers are off and there is no voltage at the unit. Measure resistance of element assemblies: 7. Record your results in the Water Heater questionnaire. Figure 8 COPPER MODULE Top View Rear of Heater Black polymer modules only (Fig. 7): 1. 2. 3. Using a 200 ohm range on a digital multi-meter, test all the elements on left heating module. ― Outer to Outer (bridge to brown wire) ― Inner to Inner (bridge to gray wire) ― Middle to Middle (red wire to red wire - 27 kW models only) Bridge C A B Using a 200 ohm range on a digital multi-meter, test all the elements on right heating module. ― Outer to Outer (bridge to white wire) ― Inner to Inner (bridge to black wire) ― Middle to Middle (red wire to blue wire - 27 kW models only) Thermal C Cutout Front of Heater Record your results in the Water Heater questionnaire. All models: Figure 7 POLYMER MODULE Top View Rear of Heater le dd Mi r te Ou 8. Using the 2000K, 2M, or 20M (Mega ohm) range on a digital multi-meter, test each element tip to ground. 9. Record all readings along with where you encountered them. 10. Using the 200 ohm range on a digital multi-meter, test the resistances across the terminals of the TCOs (Thermal Cut Outs). Tip: 17kW units have a single set of terminals to test and 27kW units have two. er Inn er Inn Bridge le dd Mi ter Ou Thermal C Cutout Front of Heater Copper modules only (Fig. 8): 4. Using a 200 ohm range on a digital multi-meter, test all the elements on left heating module. ― Bridge to blue wire ― Bridge to red wire 5. Using a 200 ohm range on a digital multi-meter, test all the elements on middle heating module (27 kW models only). ― Bridge to gray wire ― Bridge to brown wire 6. Using a 200 ohm range on a digital multi-meter, test all the elements on right heating module. ― Bridge to black wire ― Bridge to white wire Data subject to change without notice | Printed in the USA | BTC 722002306 C | 10.2013 Bosch Thermotechnology Corp. EP-25 | AE115, AE125, RP17PT, RP27PT | 5 | Step 6 – Troubleshoot the control board Troubleshoot triacs on the control board 1. Check that the triac screws are snug. 2. Using a 200 ohm range on a digital multi-meter, test the triac resistances between the middle and bottom solder connections. Tip: 27kW units have six triacs and 17kW units have four. Figure 9 1 2 3 4 5 6 Incoming cold water supply 3. Record your results in the Water Heater questionnaire. Data subject to change without notice | Printed in the USA | BTC 722002306 C | 10.2013 Bosch Thermotechnology Corp. 6 | EP-25 | AE115, AE125, RP17PT, RP27PT Questionnaires Building and Installation: STEP 1: Owner’s Name? Owner’s address? Owner’s phone number? Model and serial number? Model: Serial Number: Name of installer and phone number? Installer: Phone: Date of installation? Date of Installation:____/____/____ Where did you purchase this water heater? Where in the building is this water heater installed? Water supply and water pressure? Municiple What is the water supply material? Copper Plastic If plastic, does plastic piping connect directly to unit? Yes No When facing water heater, which side of the water heater does the cold water pipe connect? Left side Circuit breaker size and quantity Single pole Amperage:________ STEP 2: To what position is the temperature knob set? Well Water pressure:_______PSI Right side Double pole Quantity:________ Low Middle High Fixture(s) used for troubleshooting this water heater? Sink Shower Tub Flow rate of fixture(s) used for troubleshooting? _______GPM Inlet filter screen clean? Yes No Plumbing crossover test results - crossover present? Yes No Yes No Are there any cracked or melted wires in the unit? Yes No Are there any damaged plastic components in the unit? Yes No Is the flow transducer spinning? Yes No All Fixtures Water Heater: STEP 3: Are there any burn or scorch marks on the PCB? Pair 1 - L1 to L2: ________VAC STEP 4: Feed voltage: Pair 2 - L1 to L2: ________VAC Pair 3 - L1 to L2: ________VAC (27kW only) Pair 1 - L1 to L1: ________VAC L2 to L2: ________VAC Feed voltage polarity: Pair 2 - L1 to L1: ________VAC L2 to L2: ________VAC Pair 3 - L1 to L1: ________VAC L2 to L2: ________VAC (27kW only) Voltage to PCB: Data subject to change without notice | Printed in the USA | BTC 722002306 C | 10.2013 ________VAC Bosch Thermotechnology Corp. 7 | EP-25 | AE115, AE125, RP17PT, RP27PT Water Heater continued: STEP 5: Right hand module element resistance in ohms: Left hand module element resistance in ohms: Right hand module element resistance in ohms: Middle module element resistance in ohms: Left hand module element resistance in ohms: (models with polymer modules only) (models with polymer modules only) (models with copper modules only) Are there any grounded elements? If so, which ones? Outer to Outer:______Ω Middle to Middle: ______Ω Inner to Inner ______Ω Outer to Outer:______Ω Middle to Middle: ______Ω Inner to Inner ______Ω A to C:______Ω B to C:______Ω A to C:______Ω B to C:______Ω A to C:______Ω B to C:______Ω Yes No Thermal Cut Out readings: Right hand module Top terminals________Ω Bottom terminals________Ω Thermal Cut Out readings: Left hand module Top terminals________Ω Bottom terminals________Ω STEP 6: Are the triac screws all tight? Triac resistances as appropriate for the unit: Yes No Triac 1______Ω Triac 2______Ω Triac 3______Ω Triac 4______Ω Triac 5______Ω Triac 6______Ω Notes: After completing this questionnaire, please have your technician call us while still at the unit at 1-866-330-2729 for diagnosis and resolution. If it is more convenient for you, please email the completed questionnaire to [email protected] us.bosch.com and we will reply within one business day. Bosch Thermotechnology Corp. 50 Wentworth Avenue Londonderry, NH 03053 Tel: 1-866-330-2729 Fax: 1-603-965-7581 www.bosch-climate.us Data subject to change without notice | Printed in the USA | BTC 722002306 C | 10.2013 Bosch Thermotechnology Corp.
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