Install Manual

FAILURE TO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY
BEFORE INSTALLING OR OPERATING THIS CONTROL COULD CAUSE
PERSONAL INJURY AND/OR PROPERTY DAMAGE.
PARTS INCLUDED
• 48P21-811 Air Handler Control
• Thermostat Harness Assembly
(for replacing old board 47-100436-04)
• Updated Unit Wiring Diagram
DESCRIPTION
INSTALLATION, MOUNTING AND WIRING
SPECIFICATIONS & TIMINGS
ELECTRICAL RATINGS:
Input Voltage:
25 VAC, 50/60 Hz (Class II transformer)
Operating Temperature Range:
-40° to 175°F (-40° to 80°C)
Humidity Range:
5 to 95% relative humidity
(non-condensing)
Agency Approvals:
UL
PART NO. 37-7726001
1815
48P21-811
Rheem Air Handler Control for
PSC Blower Motor
INSTALLATION INSTRUCTIONS
The 48P21-811 is an aftermarket OEM Direct replacement control kit for Rheem air handlers with PSC blower
motors.
CAUTION
!
Risk of Electric Shock.
Disconnect electric power
to system until installation
is complete. Do not use on
circuit exceeding specified
voltage. Higher voltage will
damage control and could
cause shock or fire hazard.
This control is not intended
for use in locations where
it may come in contact with
water.
May cause flame rollout.
Shut off main gas to heat-
ing system until installa-
tion is complete.
white-rodgers.com
emerson.com
• 5 - Wire Nuts
• 2 - Wire Ties
• Installation Instructions
TIMINGS:
Thermostat
Input
Blower
ON Delay
Blower
OFF Delay
G 2 seconds 30 seconds
W1 or W2 2 seconds 75 seconds
NOTE: All wiring should be installed according to local and
national electrical codes and ordinances.
1. Disconnect electrical power, then remove unit access
panels.
2. If unit already contains the newer control design with a
pin header for thermostat connections, simply replace
the board and discard the wiring harness and updated
wiring diagram. Otherwise:
3. Remove old board from bracket leaving all wiring
connected to it. Mount new board in its place.
4. If unit has a heater kit disconnect wiring harness coming
from heater and plug directly into new board.
5. Transfer the following quick-connect wiring points from
the old board to the new board: “XFMR-R”, “XFMR-C”,
“COM”. Disconnect and remove the piggyback terminal
on the “C” connection which leads to the old heater kit
connector. See Figure 1 below.
6. Transfer fan relay connections. Note that one is no longer
used. The wire connected to this point should also be
removed from the wire nut connection point at the other
end of the wire.
7. Connect the wiring harness included with this kit to
the 5-pin terminal on the new board. Match the color
coding on the thermostat wiring with the wires on this