Installation instructions
31
Greentherm T9900 SE/i – 6 720 813 635 (2019/03)
NOTICE:
A blocked breather may cause an undesired double-siphon
effect.
▶ Ensure that the breather included in the siphon is not
obstructed to allow correct function.
Verify condensate disposal/neutralization is in accordance with
federal, State, and local regulation.
This is a high efficiency appliance, condensate flow can be as
much as 2.1 gal/hr at full power.
4.6.6 Backdraft reducer
The backdraft reducer (9301BFP) is the preferred option for
limiting backdraft (see fig. 21).
The backdraft reducer (9301BFP) is sized for 3" diameter PVC.
It is possible to use Backdraft reducer (9301BFP) for 2"
installations.
This requires 2" to 3" adapters.
Fig. 21
Part # 9301BFP
Installation
For this solution to be effective, the internal flapper must be
100% closed when the water heater is not running.
Refer to fig. 23 for preferred installation positions in the vent
system.
Installation considerations:
▶ Install the damper per the supplied manufacturer‘s
instructions.
The damper is only to be used in the exhaust vent piping.
▶ Ensure directional arrow on damper label faces in the same
direction as exhaust flow.
▶ If installed horizontally, the axis must be horizontal or
slightly pitched up towards termination to ensure damper
closes 100% when heater is not running.
▶ To allow accessibility, the damper must not be installed in
an enclosed section of vent pipe.
▶ Do not install the damper in unconditioned spaces (e.g.
attics) Condensation can build up while the heater is
running which can later freeze and potentially block the
flapper.
Fig. 22
Blackflow reducer (9301BFP) installed
Fig. 23
Installation Recommendation for Placement of
Backdraft reducer
[1]
Good
[2]
Better
[3]
Best
6720608643-18.1V
6720608643-19.1V