Rinnai RUR98i Manuel D'installation Et D'utilisation page 18

Flue Installation with Concentric Venting (indoor models only)
Install the venting termination according to diagrams below and vent manufacturer's instructions.
Slope the venting 1/4" per foot toward the
appliance according to the vent manufacturer's
installation instructions.
Dispose of condensate per local codes.
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Horizontal Termination
Vertical Termination
Slope the venting 1/4" per foot toward the
appliance according to the vent manufacturer's
installation instructions.
Dispose of condensate per local codes.
Securing Screw
KBP Series Manual
Secure the first vent component to the water heater
at the flange using the provided self-tapping screw.