Johnson Controls ZL Series Installation Manual page 66

Figure 27: Reheat operation piping schematic - circuit no. 1
Callout Component
A Airflow
B Evaporator coil
C Closed solenoid valve (SOL 1)
D Accumulator
E Compressor
F Open solenoid valve (SOL 2)
Alternate mode
If the return humidity is greater than or equal to
the hot gas reheat humidity set point, and there is
no demand for cooling, C1 and AUX-HGR outputs
energize, and C2 energizes.
If there is a demand for one stage of cooling and
the return humidity is greater than or equal to the
hot gas reheat humidity set point, C1 and AUX-HGR
outputs energize, and C2 energizes.
If there is a demand for both first and second
cooling stages and the return humidity is greater
than or equal to the hot gas reheat humidity set
point, C1 and C2 outputs energize and AUXHGR de-
energizes.
66 Installation Manual ZL Series 7.5- 12.5 Ton 60 Hertz R-410A
Callout
G
H
I
J
K
L
Any additional cooling demands energize
compressor outputs, but do not change the status
of the AUX-HGR output. When the UCB detects a
need for dehumidification through the field installed
return/space humidity sensor and there is not a call
for cooling, the UCB energizes SOL 3, SOL 2, and de-
energizes SOL 1.
When there is a call 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 no. 1 in reheat mode and circuit no. 2 in
cooling mode.
When there is a call for second stage cooling, the
UCB de-energizes the HGR, which de-energizes SOL
3 and SOL 2, and energizes SOL 1. Both circuits now
Johnson Controls Ducted Systems
Component
Reheat valve (SOL 3)
Reheat coil
Refrigerant flow
Check valve
Condenser coil
TXV