Page 31
Hot Gas Reheat Start-Up And Operation
General
Hot gas reheat units provide a dehumidifying mode of
operation. These units contain a reheat coil adjacent to
and downstream of the evaporator coil. Reheat coil
solenoid valve, L14, routes hot discharge gas from the
compressor to the reheat coil. Return air pulled across
the evaporator coil is cooled and dehumidified; the
reheat coil adds heat to supply air. See figure 24 for
reheat refrigerant routing.
L14 Reheat Coil Solenoid Valve
When room conditions close the dehumidistat switch,
L14 reheat valve is energized and refrigerant is routed
to the reheat coil.
Reheat Setpoint
Reheat is factory-set to energize when indoor relative
humidity rises above setpoint. Reheat will terminate when
the indoor relative humidity falls below or the digital output
de-energizes. Turn the knob on the dehumidistat to adjust
the setpoint.
Check-Out
Test hot gas reheat operation using the following
procedure.
1- Make sure reheat is wired as shown in wiring section.
2- Initiate a dehumidification demand by adjusting
dehumidistat setpoint knob BELOW indoor
relative humidity. The blower , compressor 1 and
compressor 2 should be operating.
3- End a dehumidification demand by adjusting
setpoint knob ABOVE indoor relative humidity.
The blower, compressor 1, and compressor 2
should de-energize.
Default Reheat Operation
See table 18 for detailed unit operation.
FIGURE 24
REHEAT MODE REFRIGERANT ROUTING
EXPANSION
VALVES
REFRIGERANT
CIRCUIT 1
REFRIGERANT
CIRCUIT 2
REHEAT
VALVE
CHECK
VALVE
CONDENSER COIL
092/102 STG 1
120/150 STG 2
092/102 STG 2
120/150 STG 1
DRAWING SHOWS
102/120
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