Reheat Mode Sequence Of Operation; Reheat Operation Piping Schematic; Cooling Operation Piping Schematic - York Predator ZR series Installaton Manual

5167540-YIM-H-0518

Reheat Mode Sequence Of Operation

The MagnaDRY reheat mode of operation is designed to
remove latent heat (Humidity) from a space when there are low
load conditions and the air conditioning unit is not being
required to cool the space. The general sequence of operation
of the patented MagnaDRY reheat is outlined in the following
paragraphs.
When the Unit Control Board (UCB) detects a need for
dehumidification via the field installed return/space humidity
sensor and there is not a call for cooling, the UCB energizes
solenoids SOL 3 (HGRH), SOL 2 and the Reheat Relay (RHR),
which de-energizes SOL 1. The unit then operates with
TXV
-------->
Indoor Indoor
A r i E a v . p
F o l w C l i o
-------->
Closed
Recovery
Valve SOL #1
Figure 29: Reheat Operation Piping Schematic
TXV
-------->
Air F o l w E a v . p
--------> Coil
OPEN
Recovery
Valve SOL #1
Figure 30: Cooling Operation Piping Schematic
48
Reheat O p r e i t a n o
Check
Valve
e R e h t a
C l i o
n Discharge
Comp.
Cooling O p r e i t a n o
Check
Valve
e R e h t a
Coil
Suc on Discharge
Comp.
refrigerant flow in the evaporator reheat coil and condenser coil
#1. See Figure 29.
When there is a call for the first stage of 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 refrigerant flow in the reheat coil and condenser coil #1.
See Figure 29.
Indoor blower operation is initiated upon a call for first stage
cooling, second stage cooling or dehumidification. Anytime
there is a call for a second stage of cooling, the unit will not
operate in the reheat mode, even if there is still a call for
dehumidification. The unit will not operate in the reheat mode if
there is any call for heating. All safety devices function as
previously described in this document. See Figure 30.
-------->
Outdoor Outdoor
A r i C n o . d
F o l w C l i o 1
-------->
-------->
C n o . d Fan Cond.
--------> Coil 1
C e h k c
Valve
C n o . d
Coil 2
HGRH Valve
SOL #3
OPEN g
Recovery
Valve SOL #2
C e h k c
Valve
Cond.
Coil 2
HGRH Valve
SOL #3
CLOSED
Recovery
Valve SOL #2
Johnson Controls Ducted Systems