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Designs, materials, weights and performance ratings are approximate and subject to change without notice. Visit
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17
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.
Install horizontal exhaust
duct sloping upward to drain
condensate in duct (1/4" per foot is
recommended).
Condensate will drip from end
of horizontal ducting. Install
where dripping will not be a
nuisance or ice a hazard.
Connect exhaust ducting
using either CPVC or single
wall, welded stainless steel.
Snap-together ducting is not
recommended.
Cover external termination with rain
guard and bird screen.
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).
Exterior opening must
be at least equal to cross
section of exhaust duct.
Heater
stack
Roof
Wall
Provide independent support for
duct. Do not rest weight on heater.
Duct must be same
size or larger than
heater's exhaust
outlet.
Armstrong recommends
no bend sharper than 45°.
Bird screen
installation is
recommended.
