12 kW Electric Tankless Water Heater
Troubleshooting Guide
Models:
AE12, RP12T, US12
Technical Service Bulletin
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 OR LICENSED ELECTRICIAN.
Bosch technical support is available at 866-330-2729.
Please
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 licensed 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
Empty gallon container
Digital multi-meter
Phillips head screwdriver
Flat head screwdriver
Step 1 – Document installation details
Record information in Step 1 of the Building and Install
questionnaire on page 5.
DANGER: ELECTRIC SHOCK
FOR STEPS 2, 3 AND 4, SHUT OFF THE
CIRCUIT BREAKER POWERING THE
APPLIANCE, LOCK IT, AND VERIFY THAT
THERE IS NO VOLTAGE AT THE UNIT.
Step 2 – Water supply and water heater settings
Verify the heater is installed in one of the two positions (inlet/
outlet connection on bottom) shown in Fig. 1.
Hot
Cold
Hot
Cold
Hot
Cold
Installation #1 (front view)
Installation #2 (front view)
Hot
Cold
Hot
Cold
Hot
Cold
Installation #1 (front view)
Installation #2 (front view)
Figure 1
