L.B. White Pilot - Manual (Page 62)

Air-Proving Flapper (Sail)
Servicing
Instructions
8.3-1 1
The flapper is located in the blower outlet. As discussed in
Section 9.1, Component Identification and Function, its
purpose is to assist the air-flow switch in establishing proper
air pressure and, therefore, fan speed is achieved before the
gas valve opens. However, over a period of time, the flapper
may accumulate deposits of dust or dirt affecting its ability to
pivot, thereby creating system failures. It then will be
necessary to check this mechanism for operation.
Cleaning/Adjusting PProcedure:
1. Disconnect the electrical supply and shut off gas to the
heater.
2. Make sure the sail moves up and down freely. Check
for debris, burrs or housing alignment that would
cause the pivot points of the flapper to bind. Clean
with a soft brush or compressed air if necessary.
3. The arm of the flapper should engage the arm of the
switch when the trailing edge of the flapper body is
lifted approximately 1 1/4 in. to 1 3/8 in. off the
housing bottom or rivet (if supplied). At this distance
you should hear an audible click which are the
contacts closing within the switch.
4. If the switch contacts do not close within this distance,
then manually push in the switch arm to make sure the
switch is not defective. If a “click” is heard, normally
the switch is good and the sail arm then needs to be
adjusted. (If in doubt, check for continuity.)
5. Using a needle nose pliers, gently bend up the arm of
the flapper (NOT TTHE S SWITCH AARM) in increments until
the sail arm engages the switch arm, closing the
contacts of the switch when the sail body trailing edge
is 1 in. up off of housing bottom or rivet.
Replacing tthe FFlapper:
If the flapper ever needs replacement, you will need to
remove the fan and motor assembly from the housing. (See
Section 6.2) You can now pull up on the main body of the
flapper, thereby popping it from its mounting holes. To
replace the flapper, bend the pivot point (opposite air-proving
switch) down just enough so it allows the flapper to mount in
the support holes. Once installed, push down with enough
force nearest this pivot point to realign the pivot and the
flapper body. Test the flapper to make sure that its arm
engages the air-flow switch arm properly and that the
contacts of the switch close within the prescribed distance.
August 1999
Trailing EEdge
Rivet