Bosch AE3.4 Reference manual

Freeze Prevention
Service Bulletin TWH-E1-01
Models: AE3.4, AE7.2, AE9.5, AE12, RP1P, RP2P, RP3P, RP7P, RP9P, RP12PT,
RP1, RP2, RP3, RP7, RP9, RP12, RP12T
WARNING
ELECTRICITY IS EXTREMELY DANGEROUS.
TAKE EXTRA PRECAUTIONS AND ENSURE
ALL CIRCUIT BREAKERS ARE OFF BEFORE
PERFORMING ANY WORK TO THE HEATER.
Introduction
Please note that the instructions in the manual state that the water
heater must not be installed in a location where it may be exposed
to freezing temperatures. If the water heater is installed in a
summer cottage or other location where it may be subject to
freezing, the only way of assuring protection is to completely remove
the heater during those times the area may experience freezing
temperatures.
If the heater must be left in a space which is likely to experience
freezing temperatures (less than 32° F) all water must be drained
from the heater. Due to the coil shape of the heat exchanger, it can
be difcult to drain all the water from the heater. Even in cases
where compressed air is used to blow out the water from the heat
exchanger, water may still remain in the ow switch body and
tubing.
Draining procedure
The following suggestions are made only to help minimize the
potential for freeze damage and are not to be construed as the
recommended method for dealing with freeze possibilities. The only
recommended method for preventing freeze damage is to remove
the heater from the site whenever there is a chance of freezing.
Draining the heater to minimize the potential for freezing:
• Disconnect the electric supply.
• Shut off the cold water supply and disconnect the hot and cold
water pipes from the heater. Allow water to drain from the
heater. (Have a catch basin ready.)
• Blow short bursts of compressed air into the inlet of the heater
to remove as much water as possible.
Leaving the heater in a freezing environment may result in damage to
the heater’s heat exchanger or ow switch. Additionally, water
leakage from frozen components may damage electric components
of the heater. This damage is not covered under the heater’s
warranty.
Heater reinstallation
If the water heater was removed due to freezing temperatures, it is
important to reinstall it per the installation requirements. Water
heaters installed other than the mounting orientation shown in
Figure 1 may fail to operate. All models can be installed per
Installation #1 as shown in Figure 1. All models except AE12,
RP12PT and RP12T can be installed per Installation #2 as shown in
Figure 1.

1 2 |TWH-E1-01 | AE3.4, AE7.2, AE9.5, AE12, RP1P, RP2P, RP3P, RP7P, RP9P, RP12PT, RP1, RP2, RP3, RP7, RP9, RP12, RP12T
Data subject to change without notice | Printed in the USA | BTC 721002302 A | 10.2009 Bosch Thermotechnology Corp.
Bosch Thermotechnology Corp.
50 Wentworth Avenue
Londonderry, NH 03053
Tel: [phone]
Fax: [phone]
www.boschhotwater.com
Installation #1Installation #1
Figure 1
hot cold
hot
cold
Installation #2
wall
floor
wall
floor
front
view
front
view