Rheem 800 Series Owner's Manual page 26

INSTALLATION
SECONDARY FLUE
A secondary flue must be installed with an indoor gas water heater to discharge
combustion products outside the building.
Warning: Do not use an unlined masonry chimney as the flue for this water
heater.
The water heater is supplied with a draught diverter and adaptor assembly,
designed to receive a 75 mm diameter flue.

Remove the draught diverter and adaptor assembly from the protective
packaging.

Fit the assembly by inserting the tabs on the legs of the draught diverter into
the slots in the top of the water heater.
The secondary flue must:

be seated inside of the adaptor of the draught diverter.

be self-supporting and not impose a load on the water heater.

use a slip joint or similar to allow for disconnection.

be designed to run vertically for the maximum possible distance, and not less
than 600 mm, before any change of direction.
The flue design and installation must comply with AS 5601 or AS/NZS 5601.1.
VENTILATION
A room or enclosure where the water heater is installed, including a plant room
or residential garage, must comply with the ventilation and air supply
requirements of AS 5601 or AS/NZS 5601.1, as applicable under local
regulations. Consideration must be given to other gas burning appliances
installed in the same space.
The water heater must not be installed in an area with a corrosive atmosphere
where chemicals are stored or where aerosol propellants are released.
Remember the air may be safe to breathe, but when it goes through a flame,
chemical changes take place which may attack the water heater.
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