Hot Gas Reheat - Lennox LCH036 Installation Instructions Manual

Optional Hot Gas Reheat
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 valves, L14 and L30, route 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 47 for reheat refrigerant routing.
L14 and L30 Reheat Coil Solenoid Valves
When Unit Controller indicates room conditions require
dehumidification, L14 and L30 reheat valves are energized
and refrigerant is routed to the reheat coil.
Reheat Setpoint
Reheat is factory-set to energize when indoor relative
humidity rises above 60% (default). The reheat setpoint can
be adjusted by changing ECTO 4.25. A setting of 100% will
operate reheat from an energy management system digital
output. The reheat setpoint can also be adjusted using an
optional Network Control Panel (NCP).
Reheat will terminate when the indoor relative humidity falls
3% (57% default) or the digital output de-energizes. The
reheat deadband can be adjusted 1-10% RH by changing
ECTO 4.26.
Reheat Circuit
REHEAT MODE REFRIGERANT ROUTING
EVAPORATOR
COILS REHEAT
COILS
A91 Humidity Sensor
Relative humidity should correspond to the sensor (A91)
output voltage listed in table 25. For example: if indoor air
relative humidity is 80% + 3%, the humidity sensor output
should read 8.00VDC.
Check the sensor output annually for accuracy. Keep the air
intake openings on the sensor clean and free of
obstructions and debris.
Read Relative Humidity At Unit Controller
Press the Unit Controller menu navigation arrows and
select button to read the relative humidity. See Data -
Sensors - RH menu in the Unit Controller manual.
Relative Humidity (%RH + 3%)
NOTE
Circuit 1 and Circuit 2 are similar.
Circuit 3 and Circuit 4 are similar.
FIGURE 47
Page 44
TABLE 25
Sensor Output (VDC)
20
30
40
50
60
70
80
90
CONDENSER
COILS
COMPRESSORS
LGH/LCH420, 480, 540, 600
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00