Trane GEH 006 Manual page 15

Hot Gas Reheat (option)
For space conditioning and climate
control, Trane provides an accurate
and cost effective dehumidification
control through a hot gas reheat op-
tion. This option is designed to accom-
modate unit sizes 012, 036, 060, 180
and 240.
With this reheat option, the return air
from the space is conditioned by the
air-to-refrigerant coil, then reheated
by the reheat coil to control not only
the space temperature, but to also re-
duce the relative humidity of the
space. The moisture removal capabili-
ty of a specific heat pump is deter-
mined by the units latent capacity
rating.
Figure 24: Hot gas reheat heat pump
WSHP-PRC001-EN
Features and
Benefits
When operating in the reheat mode
(meaning the sensible temperature
has been met in the space), the humi-
distat signals the reheat relay coil to
energize, allowing the high pressure
refrigerant gas to flow from the (1)
compressor, through the (2) reheat
valve, into the (3) reversing valve, or
through the (4) reheat coil for dehu-
midification. A switching relay has
been provided for the reheat applica-
tion to adjust the blower motor from
normal operation to low speed when
hot gas reheat is energized.
Note: Trane places an air separation
space between the air-to-refrigerant
coil, and the reheat coil to allow for
maximum moisture removal.
Common Reheat Applications
The hot gas reheat option is designed
to support building applications re-
quiring fresh-air ventilation units de-
livering unconditioned-air directly to
the space. It also provides dehumidifi-
cation to large latent load spaces such
as auditoriums, theaters and class-
rooms, or anywhere humidity control
is a problem.
Do's and Don'ts in Design
The factory installed hot gas reheat
option is only available with Deluxe or
ZN524 controls packages.
A high static blower motor option will
be required to support the hot gas re-
heat option.
Water regulating valves should not be
used with the hot gas reheat option.
Trane places a thermal expansion
valve on all water-source heat pumps,
as well as ground-source heat pumps,
to regulate refrigerant flow vs. water
flow, making the heat pump more effi-
cient to run.
The water-source heat pumps with hot
gas reheat should not be used as a
make-up air unit.
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