removed to enable the DEHUM input. See Table 6 and Fig. 31
through 34. When a dehumidify demand exists, the furnace control
reduces the blower airflow by 21%.
OPERATIONAL INFORMATION
Five-minute Compressor Timeguard
This timer prevents the compressor from starting unless it has been
off for at least 5 minutes. It can be defeated for 1 cycle by
simultaneously pressing the FAN mode button and the UP button.
It is not active in the installer setup mode.
Fifteen-minute Cycle Timer
This timer prevents the start of the next cycle until at least 15
minutes after the start of the present cycle. Its job is to assure that
equipment is not cycled more than 4 times per hour (or 1 cycle
every 15 minutes). It is defeated for 1 cycle when the set point is
manually changed to provide fast response to set point change. It
can also be defeated for 1 cycle by simultaneously pressing the
FAN mode and UP buttons.
Staging Timer
In multistage heating or cooling this timer prevents any higher
stage from coming on until the previous stage has been on for 10
minutes. The timer is extended to 15 minutes for heat pump
auxiliary heat and dual fuel furnace operation.
Minimum On Time
When a cooling or heating stage is turned on, it will remain on for
at least 3 minutes. These timers are canceled when set points are
changed.
Heat/Cool Set Point Difference
The deadband between heating and cooling set points is selected
by configuration Option 14. This deadband is maintained by
allowing one set point to ’push’ the other to maintain the required
minimum difference. This is true in programming of schedules and
adjustment of set points in operation.
Auto Changeover
When the auto changeover mode is selected, a change from heat to
cool or cool to heat cannot occur until a demand exists in the new
mode and no demand has appeared in the old mode for the amount
of time selected by configuration Option 38. Note that this means
that for changeover to occur, the old mode must be and remain
satisfied for the selected changeover time. Use the 30 minute
setting for installations which should change modes only twice per
day. The 5 minute setting will allow simultaneous heating and
cooling demands to be serviced.
Emergency Heat Mode
When system is configured for a heat pump and EHEAT mode is
selected, Y outputs are disabled and W outputs only are used for
heat.
Power-On Check
When power is first applied to the system the large display
indicates the equipment type selected by DIP switches as follows:
1. AC—1-Speed Air Conditioner
2. HP—1-Speed Heat Pump
3. A2—2-Speed Air Conditioner
4. H2—2-Speed Heat Pump
5. HS—1 or 2-Speed Heat Pump with 3-Stage Auxiliary Heat
6. dF—Dual Fuel with 1-Speed Heat Pump
7. d2—Dual Fuel with 2-Speed Heat Pump
Other Messages
Small Arrow—A small arrow is located to the left of HEAT and
COOL icons which are located under the two set point displays.
These indicate when cooling or heating equipment is actually
operating. When arrows flash, equipment is waiting to come on but
is being held off by compressor timeguard, cycle timer, or because
LAT or HPT has exceeded its limits and temporarily turned
equipment off. When the humidity screen is displayed, these same
arrows show the state of the humidify and dehumidify outputs.
Multiple Sensors in a Single Zone
In applications where a zone is large or contains several rooms, it
may be desirable to have several sensors which are connected to
read their average temperature. This may be done using 4 or 9 (or
16 or 25) sensors connected in series/parallel.
Initial Power-On Performance
When power is applied to system all dampers are fully opened. As
operation progresses, the system "learns" optimum damper posi-
tions needed to maintain set points in all zones. This learning
process may require up to 2 hours of operation. Allow the system
time to complete its learning.
Overshoot Control
If for any reason a zone is over-conditioned by more than 1.5
degrees and the equipment is still operating, that zone’s damper
will fully close until the over-conditioning is less than 1.5 degrees.
Undershoot Control
If, for any reason, a zone is underconditioned, by more than 2°F.,
that zone’s damper will be fully opened until the undercondition-
ing is less than 2°F.
Temperature Balancing
Under heavy load conditions when the HVAC system does not
have sufficient capacity to maintain all set points, the system does
not automatically open all dampers fully. It continues to control
dampers to keep temperature error in each zone the same as all
others.
Ventilator Mode
An automatic ventilation mode is provided by keeping all dampers
at their final position while equipment is off. If the fan is left ON,
more air is supplied to zones which required most conditioning.
Those which required none will have their dampers closed. If 1
hour passes and there is no call for conditioning, all dampers open
fully. In addition, if the mode selection is set to OFF and the fan
selection is set to ON, all dampers will immediately open.
Outputs vs. Stages
Table 3 lists the active outputs for each stage of each possible
system configuration. G is not shown.
For 1-stage furnaces and auxiliary heat connect to W1 and leave
W2 open.
For single speed compressors, connect to Y1 and leave Y2 open.
QUICK START
The quick start procedure outlined below will allow you to use
your zoning system before you learn all the details of system
operation. This setup may be done by the installer. For the best
comfort and energy-saving results, we recommend that you read
through the Owner’s Guide and set up the system to match the
end-user’s schedule and comfort requirements.
To begin, locate the User Interface and follow the steps outlined
below: (See Fig. 14.)
Set current day and time:
1. Press NEXT DAY button until current day of the week is
shown.
2. Press SET TIME/TEMP button until the TIME icon flashes.
3. Press UP or DOWN buttons until the desired time is shown,
making sure that the AM or PM time is correct.
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