Bard W24G1DA, Installation Instructions Manual

Page: 50 / 71

Manual 2100-535
Page
50 of 71
FIGURE 19
CIRCUIT DIAGRAMS
34. PRESSURE SERVICE PORTS
High and low pressure service ports are installed on all units
so that the system operating pressures can be observed.
35. 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) &
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