IM 991-2 • MAVERICK II ROOFTOP 38 www.DaikinApplied.com
Sequences of Operation
Point 7
The discharge air temperature is again above the
Effective Discharge Cooling Set Point by more than half the
Discharge Cooling Dead Band. Since the Cooling Interstage
Timer expired at Point 6, cooling is staged up. As a result, both
DTA and DTB are zeroed and the Cooling Interstage Timer
is reset. Note that DTA and DTB are both zeroed since two
consecutive stage increase actions occurred. The discharge air
temperature continues to rise, however, because the cooling
load is still increasing.
Note:
that the elapsed time since the
last stage change in this illustration is 11.0 minutes.
Point 8
The Cooling Interstage Timer has expired. Since the
discharge air temperature is still above the Effective Discharge
Cooling Set Point by more than half the Discharge Cooling
Dead Band, another stage-up occurs. As a result, DTA (Area
K) is again zeroed out (DTB remains zeroed) and the Cooling
Interstage Timer is reset. The cooling load has leveled out, and
the discharge air temperature drops.
Point 9
The Cooling Interstage Timer has expired at the
same time that DTB (Area M) becomes equal to DTA (Area
L). Therefore, cooling is staged down, the Cooling Interstage
Timer is reset and DTA is subtracted from both DTA and DTB.
This zeros both DTA and DTB since they are equal.
Figure 42: Average Discharge Control Method
