BTU XT-70, Руководство пользователя

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91
BTU VENTILATION CORPORATION
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OFFICE 888-884-8070
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FAX 218-346-7485
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www.btucorp.com
XT-70 Control Panel 91
Door Time Average, in seconds, of the time it takes the fresh air door to travel from full closed to
full open and from full open to full closed. This average time is used to determine door
position if the system is not equipped with BTU SDX (Smart Door Controls).
Max Door Open Maximum allowable door opening, in percent, during CO
2
control. It is critical that the
fresh air door opening be limited during the refrigeration mode to avoid blocking return
air to the coils.
Refrig Operating Level
This is the lowest output level, in percent, that the refrigeration system should operate
at. If the operating level is below this setting, the fresh air doors will gradually pulse
open to false load the refrigeration system until the refrigeration level is above the ROL
setting.
Plenum Rise Maximum allowable increase, in degrees F, of the plenum temperature above setpoint,
when bringing in fresh air during Refrigeration mode. Typically set to 0.5° F.
CO
2
MANAGEMENT & REFRIGERATION CONTROL FLOW CHART:
Cooling Mode CO
2
Management
If the XT control system is in Cooling mode, the CO
2
level rises above the CO
2
setpoint and the heat switch is in
Auto, the return air heater is turned on. The heater will remain on until the CO
2
level falls 200 ppm below the
CO
2
setpoint.
Refrigeration CO
2
Management
The refrigeration minimum run time must elapse before CO
2
control is initiated.
If the refrigeration system is operating below the refrigeration operating level (ROL) setting and the plenum tem-
perature is below the allowable plenum rise, the fresh air doors will pulse open. This introduces warmer fresh air
into the storage, ensuring the refrigeration system is operating above the ROL setting. The maximum door
open setting establishes a maximum allowable door opening, in percent, to prevent low return air flow through
the refrigeration evaporator coils. This operational strategy helps prevent the refrigeration equipment from cy-
cling on and off and allows fresh air exchange during the refrigeration mode.
If the refrigeration system is operating above the ROL setting, the XT control system checks to see if the CO
2
level is above the CO
2
setpoint. If CO
2
levels are above setpoint, the plenum temperature is not above the ple-
num rise, and the door output is below the maximum door setting, the door will receive a open pulse.
If at any time the plenum rise is exceeded, the door will receive a close pulse.
When the CO
2
level drops 200 ppm below the CO
2
setpoint, the door will receive a close pulse.