Maintenance and service
5. Clean the water drain valve (with water filter) with a
brush under running water.
6. Replace the water drain valve (with water filter) and
close the drain plugs (take care not to lose the packing).
7. Close all hot water fixtures.
8. Open the water supply valve and check that water
does not leak from the drain plugs or water drain valve
(with water filter).
• Isolation valves may be purchased as an accessory
from Bosch. They allow for full diagnostic testing and
easy flushing of the system
• The kit includes two full port isolation valves and a
pressure relief valve for the hot side. Contact Bosch
for more information.
Preventing Damage from Freezing
Caution: Damage can occur from fro-
zen water within the device and pipes
even in warm environments. Be sure to
read below for appropriate measures.
Caution: Repairs for damage caused
by freezing are not covered by the war-
Freezing is prevented within the device automat-
ically by the freeze-prevention heater
Freezing cannot be prevented when the power plug is
unplugged. Do not remove the power plug from the wall
outlet (Freezing will be prevented regardless of whether
the operation switch is ON or OFF).
• In normal operation, freezing is prevented within the
device automatically unless the outside temperature
without wind is below -5°F (-21°C) (indoor installa-
tion) or -4°F (-20°C) (outdoor installation).
• The freeze prevention heaters will not prevent the
plumbing external to the unit from freezing. Protect
this plumbing with insulation, heat tape or electric
heaters, solenoids, or pipe covers. If there remains a
freezing risk, contact the nearest Bosch agent.
Take the measures below for extremely cold tem-
peratures (Only using the remote controller)
Outside temperature including wind chill factor less
than -5°F (-21°C) (indoor installation) or -4°F (-20°C)
(outdoor installation). This method can protect not only
to the heater, but also to the water supply, water piping
and mixing valves.
1. Turn off the power.
2. Close the gas supply valve.
3. Open a hot water fixture, and keep a small stream of
hot water running 0.1 gallon (400cc)/minute or about
0.2" (4mm) thick).
If there is a mixing valve, set it to the highest level.
4. The flow may become unstable from time to time.
Check the flow 30 minutes later. In general, it is not
advisable to run water through the unit when it is OFF,
but in this case freeze prevention is more important.
• Remember to set mixing valves and fixtures to their
original levels before using the unit again to prevent
• If there is still a risk that the unit will freeze, drain the
unit as shown on the next page.
If water will not flow because it is frozen
1. Close the gas and water valves.
2. Turn off the power button.
3. Open the water supply valve from time to time to
check whether water is running.
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