Armstrong International
IOM-706 V2.0
Flo-Direct Water Heater
Installing Exhaust Ducting
Page 15 of 45
Installing Exhaust Ducting
Note:
• Roof installation preferred.
• Flo-Direct heater is not naturally drafting;
exhaust is under slight pressure.
• Insulation is not required because exhaust
temperature is only a few degrees above
incoming water temperature.
Cover external
termination with rain
guard and bird screen.
Exterior opening
must be at least equal
to cross section of
exhaust duct.
Provide independent
support for duct. Do not
rest weight on heater.
Install horizontal exhaust
duct sloping upward to drain
condensate in duct (1/4" per
foot is recommended).
Roof
Connect exhaust
ducting using either
CPVC or single wall,
welded stainless steel.
Snap-together ducting
is not recommended.
Bird screen
installation is
recommended.
Duct must be
same size or larger
than heater's
exhaust outlet.
Models AFD-1000 and
AFD-1500 require a rubber
sewer connection boot to
connect. All other models
have a flange (shown). Joint
should be sealed with RTV
(clear silicone).
Heater
stack
Armstrong
recommends no
bend sharper
than 45°.
Wall
Condensate will drip
from end of horizontal
ducting. Install where
dripping will not be a
nuisance or ice a
hazard.
