York PREDATOR DR090 - Manual (Page 10)

246721-YTG-C-0606
10 Unitary Products Group
When the room thermostat calls for second stage cooling, the
RCB senses a signal through "Y1" & "Y2" and engages circuit
#1 and circuit #2 in cooling mode.
Indoor blower operation is initiated upon a call for first stage
cooling, second stage cooling or dehumidification.
Anytime there is a call for 2 stages of cooling, the unit will not
operate in the reheat mode, even if there is a call for dehu-
midification at "HUM".
The unit will not operate in the reheat mode if there is any call
for heating.
On units with economizers, the unit will not operate in the
reheat mode if there is a call for cooling and the economizer
is operating as first stage of cooling.
All safety devices function as previously described.
"ALTERNATE” MODE
When the RCB detects a need for dehumidification (24VAC)
at "HUM" via the field supplied dehumidistat connected to
RHTB-1 and RHTB-2, and there is not a call for cooling, it
energizes the HGR, which energizes the SOL 3, SOL 2, and
de-energizes SOL 1. (In the DR150, SOL 2 is only energized
when the discharge pressure in circuit #1 rises above 235
psig and de-energizes SOL 2 after the discharge pressure
falls below 175 psig. Both outdoor fans of circuit #1 in the
DR150 also disengage to conserve energy.) The unit then
operates with circuit #1 in reheat mode and circuit #2 in cool-
ing mode.
When the room thermostat calls for first stage cooling while
there is still a call for dehumidification, no operational change
is made. The call for cooling is ignored and the unit continues
to operate with circuit #1 in reheat mode and circuit #2 in
cooling mode.
When the room thermostat calls for second stage cooling, the
RCB senses a signal through "Y1" and "Y2" and de-ener-
gizes the HGR, which de-energizes SOL 3 and SOL 2, and
energizes SOL 1. Both circuits operate in the cooling mode.
Indoor blower operation is initiated upon a call for first stage
cooling, second stage cooling or dehumidification.
Anytime there is a call for 2 stages of cooling, the unit will not
operate in the reheat mode, even if there is still a call for
dehumidification at "HUM".
The unit will not operate in the reheat mode if there is any call
for heating.
All safety devices function as previously described.
FIGURE 3 - REHEAT CONTROL BOARD
R
Y1
Y2
G
W1
OCC
C
W2
P4
P5
P6
P3
COM
HGRR
HGR HUM
K1
K2
K4
K3
`
MODE
SELECTION
JUMPER
DEHUMIDISTAT
HARNESS
CONNECTION