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international.com
Designs, materials, weights and performance ratings are approximate and subject to change without notice. Visit
armstrong
international.com for up-to-date information.
48
• Remove and inspect the rear fiberboard. If any resistance is encountered with the removal of the screw securing the
fiberboard in place, do not exert undo force; break the fiberboard out to provide access to the screw. Apply penetrating
oil to the screw, let it sit, then remove. See photos below for details. Replace only after cleaning procedure. Use a new
fiberboard if moisture has fouled it or if there is any physical damage preventing it from protecting the rear wall, such as
cracks or warping. Warped fiberboards will allow the back wall to overheat, this could lead to a breach of the back wall.
This will also cause a loss of efficiency and a rise in stack temperature.
NOTE: Failure to replace front and rear fiberboard when damaged may result in irreparable damage to the appliance!
Both of these must
be replaced!
Maintenance - continued
• Check the fire side of the heat exchanger: only clean loose residue from the heat exchanger coil,
use a vacuum cleaner and nylon brush, and do not push the residue between the openings of the
coils if at all possible as this may impede the flow of the products of combustion.
• Use inspection mirror to check all heat passage spaces between coils, and using a short, thin putty
knife or strip of stainless steel, remove all debris.
These passages MUST be free and clear for
proper heat transfer to occur.
Rinse well all loose debris that was pushed down to the bottom of
the condensate collection tray.
• It is recommended to only use clear water to rinse any remaining residue away—the water will
automatically flow to the condensate drain point.
• If surface or coil gap fouling still exists after the above measures have been taken, the heat
exchanger requires additional cleaning.
Use a non-acid based cleaning solution, such as Fernox
F3, to thoroughly soak the remaining residue. Brush clean and then completely rinse all residue
and cleaning solution down the condensate drain assembly. Repeat if necessary.
(See complete cleaning instructions on page 49-51)
