BTU XT-70 - Page 101

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101

BTU VENTILATION CORPORATION ● OFFICE 888-884-8070 ● FAX 218-346-7485 ●

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XT-70 Control Panel 101

Purge Cycles During Refrigeration:

Purge 7 will also allow the system to purge CO2 during refrigeration. The ARL (ambient re-

verse loading) is also available in purge 7. The ARL will use the fresh air doors and ambient

air to reverse load the refrigeration coils if the refrigeration level is very low and about to shut

off. To disable the ARL, set the ROL E2 parameter to zero. If the CO2 level rises above the

CO2 setpoint, the fresh air doors will gradually open to purge the CO2. Once the CO2 level

drops below the CO2 Setpoint minus the CO2 differential, the doors will slowly close.

Purge Cycle During Standby:

If refrigeration is not available and the ambient air becomes too warm, the system will go into

Standby. If the CO2 level is above the CO2 Setpoint, a forced Cooling cycle will begin. The

fresh air doors will only open to the Max Open setting. Once the CO2 drops below the differ-

ential setting, the MCR (minimum cooling run) will clear and the system will go back to

Standby.

CO2 > CO2 SP

yes

CO2 <

CO2SP - DIFF

RUN PID HEAT

MODE & CO2 PURGE

SP = SP + CO2 PLEN RISE

MODE =

CO2

RUN PID HEAT

MODE & CO2 PURGE

SP = SP - CO2 PLEN RISE

Door = 0 %

yes

yesno

MAIN LOOP

RETURN

Mode =

Standby

yes

Time Clock =

Cooling Only

CO2 >

CO2 SP

yes

Force Cooling