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Technical Service Bulletin
High kW Electric Tankless Water Heater
Troubleshooting Guide
Models: WH17, WH27, WH36 AE115, AE125, (FD108 and higher)
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.
BOSCH ELECTRICAL APPLIANCES
SHOULD ONLY BE SERVICED BY A TRAINED
TECHNICIAN.
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
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.
Step 1 – Document installation details
Complete the "Building and Install" questionnaire.
Step 2 – Water supply and water heater settings
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.
Bottom of Heater
Bottom of Heater
2.
Document your fi ndings in the Building and Installation
questionnaire.
Verify flow rate
1.
Using a graduated container (a ½ or 1 gallon container
works well), time how long it takes to fi ll it with water
from a hot water only faucet or shower. Calculate the fl ow
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.
Figure 1
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Summary of Contents for Bosch WH17
- Page 1 Technical Service Bulletin High kW Electric Tankless Water Heater Troubleshooting Guide Models: WH17, WH27, WH36 AE115, AE125, (FD108 and higher) Step 1 – Document installation details DANGER: ELECTRIC SHOCK Complete the “Building and Install” questionnaire. ELECTRICITY IS EXTREMELY DANGEROUS.
- Page 2 2 | WH17, WH27, WH36 AE115, AE125, (FD108 and higher) Example: 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 Water collected (gallons) the water heater, you cannot perform this test.
- Page 3 WH17, WH27, WH36 AE115, AE125, (FD108 and higher) | 3 | Figure 3 Figure 5 27/36kW terminal block 27/36kW terminal block Supply 1 Supply 1 Supply 2 S S upply 2 Supply 3 Supply 3 To Supply 1 T T o Supply 1...
- Page 4 4 | WH17, WH27, WH36 AE115, AE125, (FD108 and higher) Step 5 – Troubleshoot the element assemblies Verify that circuit breakers are off and there is no voltage at the Using a 200 ohm range on a digital multi-meter, test all the unit.
- Page 5 WH17, WH27, WH36 AE115, AE125, (FD108 and higher) | 5 | Questionnaires Building and Installation: STEP 1: Owner’s Name? Owner’s address? Owner’s phone number? Model and serial number? Model: Serial Number: Where did you purchase this water heater? Name of installer and phone number?
- Page 6 6 | WH17, WH27, WH36 AE115, AE125, (FD108 and higher) Water Heater continued: Outer to Outer:______Ω STEP 5: Right hand module element resistance Middle to Middle: ______Ω (27/36kW only) in ohms: Inner to Inner ______Ω Outer to Outer:______Ω Left hand module element resistance in ohms: Middle to Middle: ______Ω...