Bard QTEC QH303D Installation Instructions Manual Download

Page: 29 / 38

Manual

2100-435D

Page

29 of 38

the return air thermostat sensed a temperature below 65°
during dehumidification, the fist stage electric heaters
are brought on to raise the return air temperature above
65°. When the humidistat is satisfied, the system
switches back to normal air conditioning mode.

If the thermostat calls for cooling during
dehumidification mode, the call for cooling takes
precedence over the dehumidification and the unit will
cool until the thermostat is satisfied. Once the call for
cooling is satisfied, the unit may continue to
dehumidify.

If the thermostat calls for heat when the unit is in the
dehumidification mode, the electric heaters will
energize and the evaporator air flow will return to the
heating air flow. When the thermostat is satisfied, the
electric heaters will turn off and the air flow will be
reduced and the system will continue to dehumidify
until humidistat is satisfied.

If the unit is running in heat pump mode and the
humidistat calls for dehumidification, the
dehumidification mode takes precedence over the heat
pump heating mode. The unit will not return to the
heating mode until 2nd stage heating is called for.

The Climate Control

Option G

has a non-programmable

electronic thermostat, humidistat and is compatible for
use with a CS2000A Energy Control Monitor. This unit
has a refrigerant reheat circuit that is controlled by a
three-way valve.

Unit operation is controlled by the thermostat and
humidistat, and optional CS2000A Energy Monitor
Controller can be easily integrated by simple connection
to the low voltage terminal block provided. See Figure
16C.

NOTE: The CS2000A (or other means for ventilation

control) must be used if any mechanical
(motorized) ventilation options are installed.

Dehumidification can be set to be available only when
CS2000A is active or to be available continuously by
switching a jumper on the relay logic board. See notes
on Table 12.

When the humidity is above the setpoint of the
humidistat, the compressor circuit and the 3 way valve
are energized and the evaporator air flow is reduced.
The 3 way valve directs hot discharge gas into a
separate desuperheating condenser circuit that reheats
the conditioned air before it is delivered to the room. If
the return air thermostat sensed a temperature below 65°
during dehumidification, the fist stage electric heaters
are brought on to raise the return air temperature above
65°. When the humidistat is satisfied, the system
switches back to normal air conditioning mode.

REFRIGERANT TUBE SCHEMATIC FOR
REHEAT COIL

Figure 20 shows the refrigerant gas flow through the
reheat coil during the dehumidification mode.

When the unit is in standard cooling (Figure 21) or
heating mode the reheat coil is inactive.

PRESSURE SERVICE PORTS

High and low pressure service ports are installed on all
units so that the system operating pressures can be
observed. Pressure curves can be found later in the
manual covering all models on both cooling and heating
cycles. It is imperative to match the correct pressure
curve to the unit by model number. Upper and lower
service doors must be attached to obtain proper reading.

FIGURE 19

LOW PRESSURE CONTROL BYPASS TIMER

MIS-1917