Bard W24G2DA, Installation Instructions Manual

Page: 50 / 69

Manual 2100-592C
Page
50 of 69
FIGURE 19
Circuit Diagrams
35. PRESSURE SERVICE PORTS
High and low pressure service ports are installed on
all units so that the system operating pressures can be
observed.
36. DEHUMIDIFICATION CIRCUIT
The dehumidification circuit incorporates an
independent heat exchanger coil in the supply air
stream. This coil reheats the supply air after it passes
over the cooling coil without requiring the gas burner to
be used for reheat purposes. This results in very high
mechanical dehumidification capability from the air
conditioner on demand without using gas reheat.
The dehumidification refrigerant reheat circuit is
controlled by a three way valve directing the refrigerant
gas to the normal condenser during periods when
standard air conditioning is required. During periods of
time of low ambient temperature (approximately 65° to
75° outdoor) and high indoor humidity, a humidistat
senses the need for mechanical dehumidification. It
then energizes both the compressor circuit and the
three way valve, thus directing the hot refrigerant
discharge gas into a separate desuperheating
condenser circuit, which reheats the conditioned air
before it is delivered to the room. The refrigerant gas
is then routed from the desuperheating condenser to
the system condenser for further heat transfer. A small
orifice inserted between the reheat coil return line and
suction line will prevent liquid from accumulating in
the reheat coil when it is inactive. This drain does not
affect the normal operation of the system. A check
valve is located in the reheat oil return line. It has
a soft spring to hold the ball on the seat. This will
make the method of checking the ball freedom with a
magnet difficult. Refer to Figure 19 for the location
of the check valve and drain back capillary. When
the humidistat is satisfied, the system automatically
switches back to normal air conditioning mode and
either continues to operate or turns off based on the
signal from the wall thermostat. The result is separate
humidity control at minimum operating cost.
Air Conditioning Mode
Circuit Diagram
Dehumidification Mode
Circuit Diagram