Freeze Protection Piping - A.O. Smith 705 Operation & Installation Manual

Direct vent tankless water heater
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Freeze Protection Piping

NOTICE
Warranty does not cover damage due to freezing.
When electrical power and gas are supplied to the
water heater, it will not freeze in environments as cold
as -30º F when protected from direct wind exposure.
In the event of a power failure at temperatures below
freezing the water heater should be drained of all
water to prevent freezing damage.
The unit may be drained manually. However, it is
highly recommended that drain down solenoid valves
be installed that will automatically drain the unit if
power is lost. It is also recommended that a sub-PC
board be installed that attaches to the PC board in the
unit and allows the solenoid valves to operate if the
unit is disabled due to an error code.
When the electrical power to the water heater fails, the
3/4" solenoid valve closes (stopping the flow of water
into the heater) and the 1/2" solenoid valve opens
(allowing the water heater and associated piping to
drain. Ensure that you run the drain for the solenoids
to the outside environment to prevent discharging
water inside the building causing water damage).
NOTE:
Heat trace ALL water pipe and fittings located
outside home (attic, crawl space) or building
structure. (ALL water pipe and fittings shown
above the dashed line in the drawing.)
NOTE:
ALL pipe and fittings shown below dashed line
should be located inside home or building
structure.
The vacuum breaker line should be located
inside the building structure.
3/4" Ball Valve
3/4" Union
Check Valve
Pressure Relief Valve
18
Minimum 3/4" Hot Water
KEY
Pressure Regulator
Circulating Pump
Boiler Drain Valve
S
Solenoid Valve
305, 505, 705 Indoor Manual
Water Heater
Supply Line
1/2" Minimum
Normally Open
Solenoid Valve
This is not an engineered drawing. It is intended only as a guide and not
as a replacement for professionally engineered project drawings. This
drawing is not intended to describe a complete system. It is up to the
contractor/engineer to determine the necessary components and
configuration of the particular system being installed. This drawing does
not imply compliance with local building code requirements. It is the
responsibility of the contractor/engineer to ensure installation is in
accordance with all local building codes. Confer with local building
officials before installation.
Vacuum
Breaker
S
3/4" Minimum
Normally Closed
Solenoid Valve
Route to Floor Drain

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