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Configuring Unit
This section identifies the requirements for configuring the air handler unit for unit size, heat mode selection and EvenHeat.
Air Handler Control Checkout
Power−up − Unit Size Code (Number or letter) displayed represents air handler model size and
capacity. If three horizontal bars displays, Air Handler Control (AHC) does not recognize unit size code
(air handler model size and capacity).
AHC
recognizes
Unit Size
Code?
Electric
heat
Installed?
Finished
Which
Heat
Mode
?
Refer to EVENHEAT Operation flow diagram, Air Handler or
ECB40 Electric Heat installation instructions.
W1 Call?
Yes
No
Yes
No (Display Alarm
Code 203)
Standard
EVENHEAT
Refer to
Heat Pump
or
Cooling
Sequence of Operation
flow
diagrams, Air Handler or ECB40
Electric Heat installation
instructions.
A call for electric heating first, second or third stage is
initiated when 24 VAC (R) is detected on W1, W2 and
W3 inputs on AHC. (Factory mounted metal jumpers
connect W1/2 and W2/W3.)
At the completion of each heat section demand (W1,
W2, and W3), the AHC will immediately de−energize
the corresponding pilot relay(s).
At the completion of all heating demands, the indoor
blower will run for an additional 10 seconds before
de−energizing.
No
Yes
NOTE If the call for lower heat section is removed,
AHC will automatically de−energize higher heat
sections.
Indoor blower will immediately start to delivery CFM
as set by heating mode jumper on AHC with
activation of first electric heat pilot relay.
Pilot relays on AHC are energized one at a time.
There is a minimum of 10 seconds delay between
pilot relay activations.
After all electric heat installations, AHC must be
manually configured to detect number of heat
sections. Refer to Configuring/Detecting electric heat
sections flow diagram, Air Handler or ECB40 Electric
Heat installation
IMPORTANT
Field replacement controls may need to be manually
configured to validate air handler unit size code.
Refer to
Configuring Unit Size Codes
flow diagram, Air Handler or
ECB40 Electric Heat installation instructions.
ONE (H1)
H1
TWO (H1−H2)
H1
H2
H2
THREE (H1−H3)
H1
H2
H3
FOUR (H1−H4)
H1 AND H2
H3
H4
FIVE (H1−H5)
H1 AND H2
H3 AND H4
H5
T−STAT CALL
W1
W2
W3
NUMBER OF HEAT SECTIONS DETECTED
NOTE − AHC will not recognize higher heat sections
calls if lower heat section is not present.
RECOMMEND
USE FIGURE 21 AS A REFERENCE FOR SETTING JUMPER CONFIGURATIONS ON THE AIR HANDLER CONTROL.
Figure 22. Air Handler Control Checkout
