50
Rev. 05/2020
CHAPTER 14
AIR SUPPLY
Combustion Air Blower(s) and Flipper Assembly(s)
Principles
The combustion air blowers and flipper assemblies supply air for combustion inside the
firebox. The flipper assemblies keep air out of the firebox when combustion is not needed.
These components are removable and serviceable.
Operation of the Combustion Air Blower(s) and Flipper Assembly(s)
1)
When the HTF temperature reaches the
high HTF temperature
setting, the aquastat
turns the blower(s)
off
. At this point, the hinged flipper falls shut, preventing air from
getting into the firebox.
2)
When the HTF temperature reaches the
low HTF temperature
setting, the aquastat
turns the blower(s)
on
. At this point,
the hinged flipper opens from the force of the
blower(s) and allows air into the firebox.
3) The hinged flipper
must
completely open
and close all of the time. When it is closed,
it must seal completely. If more than a
“wiff” of smoke is coming from the chimney
when the blower(s) has been off for
approximately 10 minutes, this is a strong
indication the hinged flipper is not shutting
properly.
Maintenance / Result
1) Clean the fin blades of the squirrel cage fan.
2) Ensure the flipper assembly is clean and seals completely when closed.
Steps to Maintain your Blower / Flipper Assembly.
1) Turn off the main power supply to the furnace.
2) Loosen and remove the two thumb nuts securing the blower / flipper assembly to the
large air tube, and remove the blower / flipper assembly.
3) With a small brush, scrape any dust or residue that has accumulated on the fins of the
blower.
4) With a small brush or scraper, scrape any dust or residue built up on the flipper
assembly.
5) Ensure the flipper is resting completely on its seat. If it is not resting completely,
perhaps there is dust or soot built up on the flipper, or some other obstruction not
allowing it to close tightly.
6) Securely fasten the blower/flipper assembly back to the large air tube ensuring there
are no air leaks.
THE FLIPPER MUST OPERATE PERFECTLY OR PROBLEMS QUICKLY ARISE.
Flipper Assembly
