Bard MEGA-TEC W090A, Service Instructions Manual

Page: 36 / 159

Manual 2100-671C
Page 34 of 59
5. Press ENTER key to scroll to Enable .
6. Press UP or DOWN keys to change the value from
Yes to No .
An electric reheat capable unit will allow for concurrent
operation of compressor and electric heat. This allows
the compressor to operate which will remove moisture
from the indoor air while the electric heat keeps the
space temperature from dropping during this operation.
The cooling capacity of the MEGA TEC is much greater
than its capacity to heat with either the 9kw or 18kw
option. In order to extend the compressor run times
and prevent the unit from overcooling the space, the
cooling capacity will be limited during dehumidification
operation (see Table 11).
FIGURE 49
Electric Reheat Dehumidification
Electric Reheat Dehumidification Operation
The unit will utilize electric reheat dehumidification
when it receives an active dehumidification call from
the LC6000 supervisory controller. During the active
dehumidification call, the unit status message will
show “Active Dehum”. An LC6000 equipped with
and indoor humidity sensor is required to utilize
dehumidification.
When the command is received from the LC6000, or
generated by unit with stand-alone display, the wall
unit will engage the compressor to begin removing
moisture from the space and turn on the electric
heat to extend the run time of the cooling cycle while
mitigating the cooling done by the compressor. If/
when the return temperature falls to 2° above heating
setpoint, the compressor will be disabled until the
temperature is increased to 2° below the cooling
setpoint and then compressor will be re-energized (see
Figure 50). If/when the temperature reaches 4° below
the cooling setpoint, the electric heating elements will
be energized. The electric heating elements will be
disabled 2° below the cooling setpoint. The system will
continue the dehumidification process until either the
heating or cooling setpoint are reached again or the
active dehumidification command has been removed.
A heating or cooling call will disable the
dehumidification call. Dehumidification can only
take place when the system is not actively heating or
cooling.
For more information on dehumidification staging, see
latest version of LC6000 Service Instructions manual
2100-669.
TABLE 11
Cooling Capacity Limitation
Heat
Option
Limitation
Heat
Capacity*
Cooling Capacity*
7.5 Ton Cooling Capacity 10 Ton Cooling Capacity 12.5 Ton Cooling Capacity
9 Kw
Compressor
1 Part Load
30,709 29,700 39,600 49,500
18 Kw
Compressor
1 Full Load
61,418 45,000 60,000 75,000
* Capacities listed are nominal and don't reflect actual performance.
FIGURE 50
Dehumidification Control (°F)
58
Reheat
Cool
59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79