27
DIP SWITCH NO. 1 — Supply Air Set Point (SASP) Reset
Type. Factory setting is OFF. Do not change.
DIP SWITCH NO. 2 — SASP Reset Enabled. Factory setting
is OFF (no SASP reset enabled). If SASP reset has been
installed, enable it by changing switch position to ON.
DIP SWITCH NO. 3 — Economizer option. If economizer
option has been installed, this switch will be ON. If there is no
economizer installed, this switch will be OFF. For all 48FM
and 50FM,FS units, this switch will be ON. Confirm setting
per Table 10. Change only if in error.
DIP SWITCH NO. 4 — Morning Warm-Up. For 48FK,FM,JK
units, this switch will be ON (morning warm-up enabled). For
50FK,JK units with factory-installed electric heaters, this
switch will be ON. For all other units, this switch will b e OFF.
If accessory electric heaters are installed (for 50FK,JK 034-
074 units without plenum option), change this switch to ON.
DIP SWITCH NO. 5 — Demand Limit. Factory setting is OFF
(demand limit not enabled). If Demand Limit (single-step or
2-step accessory) has been installed, change this switch to ON.
DIP SWITCHES NO. 6 AND NO. 7 — Unloader Configu-
ration. These are factory set to match unit size. Confirm set-
tings per Table 12. Change only if in error.
Table 12 — DIP Switches
LEGEND
*Control circuit breaker must be off before changing the setting of the DIP
switch.
†No economizer.
**And/or electric heat (50FK,JK034-074 units without plenum only).
Adjusting Set Points — Set points for unit operation
are established via potentiometer settings. Set points for Supply
Fan controls are set at the VFD keypad (if installed) or at the
IGV differential pressure switch (DPS1) (if IGV option in-
stalled). Set points for modulating power exhaust (option or ac-
cessory) are set at the differential pressure switch (DPS2).
Set points for high capacity modulating power exhaust
(48FM and 50FM,FS units) are set at the power exhaust VFD
keypad.
Potentiometers — All of the set point potentiometers
must be set before the unit is started in order for the unit to
function properly. Each of the potentiometers has a valid range
that is used by the control. The valid range is defined as the po-
tentiometer’s resistance value that the control will not con s ider
to be in error. This is usually between 10% and 90% of the po-
tentiometer’s total resistance. The control has been pro-
grammed to accept an operational range for the potentiometer,
which may not be the same as the valid range.
Potentiometer inputs and ranges are summarized in Table 9.
Information on individual set point potentiometers (including
function, location and range data) are shown below:
SUPPLY AIR SET POINT (Leaving-Air Temperature) (P1)
— This potentiometer establishes the set point for cooling
cycle operation of the VAV unit. The VAV control uses a valid
control range of 45 to 70 F, and the potentiometer has a valid
range of –22 to 70 F. If the set point is between –22 and 45 F,
the control will use a value of 45 F. If the set point is outside
the valid range (less than –22 F or greater than 70 F), an alarm
condition will be signaled and a default value of 70 F will be
used.
ECONOMIZER MINIMUM POSITION (P5) — This potenti-
ometer specifies the minimum opening position for the
optional economizer during running periods. It has both a valid
range and an operational range of 0 to 100%.
SASP RESET TEMPERATURE (P7) — This potentiometer
establishes the space temperature at which the control will ini-
tiate the reset of the SASP (i.e., the unit control begins to raise
the base SASP, to prevent overcooling of the space). The
potentiometer has a valid range of 40 to 100 F. Refer to Space
Temperature Reset section on page 13 for further discussion of
SASP Reset operation.
RESET LIMIT (P3) — Used in conjunction with P7 potenti-
ometer, this potentiometer establishes the maximum tempera-
ture for the modified SASP value during the Reset function.
This potentiometer has a valid range of 0° to 80 F.
DEMAND LIMIT, SINGLE-STEP (P4) — This potentiome-
ter establishes the maximum amount of compressor capacity
permitted by the unit control when single-step demand limit
operation is implemented (by closing contact set to potentiom-
eter wiper arm). This potentiometer is field-supplied and
-installed and will be located in the main control box. The
valid range is 0% to 100%, which is also the operational range.
If the wiper arm is open, all capacity stages can be used.
When the wiper arm is closed, the capacity is reduced by the
amount set on potentiometer P4.
DEMAND LIMIT, 2-STEP — The accessory 2-step demand
limit control is a 2-potentiometer system. The demand limit
control board (DLCM) accessory board is field-installed in the
main control box; the 2 control potentiometers are located on
the DLCM. Potentiometer DLCM-P1 establishes the maxi-
mum amount of compressor capacity available when SW1 is
closed and has a valid range is 50% to 100%. Potentiometer
DLCM-P2 establishes the maximum amount of compressor
capacity available when SW2 is closed and has a valid range is
0% to 49%.
If no power is supplied to the DLCM, all capacity stages
can be used. When power is supplied to terminal IN1 only, the
first step of demand limit control is energized and the capacity
is reduced by the amount set on potentiometer P1. When power
is supplied to IN2 (or IN1 and IN2), the capacity is reduced by
the amount set on potentiometer P2.
MORNING WARM-UP (P6) — This potentiometer estab-
lishes the set point temperature for the Morning Warm-Up
function. This is the temperature at which the morning warm-
up sequence is terminated and VAV cooling operation begins.
The valid control range is 0° to 95 F, but the control is pro-
grammed to accept a range of 40 to 80 F. If the set point is
between 0° and 40 F, the control will use a value of 40 F. If the
set point is between 80 and 95 F, the control will use a value of
80 F. If the set point is outside the valid range (less than 0° F or
greater than 95 F, an alarm condition will be signaled and a
default value of 40 F will be used.
SWITCH
NO. FUNCTION SWITCH
POSITION* MEANING
1Reset
Mode Off Space or Outdoor-Air Reset
(DO NOT CHANGE)
2Reset
Select
On
Off
Reset Used
Reset Not Used
3Economizer On
Off
Enable Economizer
Disable Economizer†
4Morning
Warm-Up
On
Off
Enable Morning Warm-Up**
Disable Morning Warm-Up**
5Demand
Limit
On
Off
Enable Demand Limit
Disable Demand Limit
6,7 Unloaders
Off, Off
On, Off
Off, On
No Unloaders
1 Unloader
2 Unloaders
8Not Used Off No Significance
DIP — Dual, In-Line Package