Space Pressure Control - Trane Voyager Commercial Installation, Operation And Maintenance Manual

1 (Fan ON) or Step 2 (Economizer Open) and make
the proper adjustment.
• To set the Design Minimum Position setpoint at
Middle Fan Speed, set the unit to operate at Step 3
(Cool 1) and make the proper adjustment.
• To set the Design Minimum Position setpoint at Full
Fan Speed, set the unit to operate at Step 4 (Cool 2)
and make the proper adjustment.
Figure 43. SZVAV OA damper min position w/ OA
CFM compensation
Design @ Minimum
Fan Speed
OAD
Position
Setpoints
Design @ Middle
Fan Speed
Design @ Maximum
Fan Speed
Minimum Fan
Speed

Space Pressure Control

For units configured with an exhaust fan, with or
without Statitrac, the control described previously for
economizer minimum position handling requires
additional changes to the existing Space Pressure
Control scheme. The overall scheme will remain very
similar to non-Single Zone VAV units with Space
Pressure Control with the exception of a dynamic
Exhaust Enable Setpoint.
For Single Zone VAV the user will select an Exhaust
Enable Setpoint during the Maximum Fan Speed
Command. Once selected, the difference between the
Exhaust Enable Setpoint and Design OA Damper
Minimum Position at Maximum Fan Speed Command
will be calculated. The difference calculated will be
used as an offset to be added to the Active Building
Design OA Minimum Position Target to calculate the
dynamic Exhaust Enable Target to be used throughout
the Supply Fan Speed/OA Damper Position range.
The Exhaust Enable Target could be above or below
the Active Bldg Design OA Min Position Target
Setpoint based on the Active Exhaust Enable Setpoint
being set above or below the Bldg Design Min Position
at Full Fan Speed Command.
N N o o t t e e : : An Exhaust Enable Setpoint of 0% will result in
the same effect on Exhaust Fan control as on
non-Single Zone VAV applications with and
without Statitrac.
RT-SVX34R-EN
Middle Fan Maximum Fan
Speed Speed
Figure 44. Space pressure control graph
OAD
Position
Setpoints
Exhaust Enable Target
Exhaust Enable @
Maximum Fan Speed
Exhaust Enable @
Maximum Fan Speed
Design @ Maximum
Fan Speed
Minimum Fan Speed Middle Fan Speed
Fan Speed Algorithm Command
Table 31. RTVM space pressure setpoint
Voltage (Vdc) Setpoint (IWC)
0.04
0.118
0.196
0.274
0.352
0.43
0.508
0.586
0.664
0.742
0.82
0.898
0.976
1.02
1.08
1.129
1.178
1.227
1.276
1.325
1.374
1.423
1.472
1.521
1.57
1.619
1.668
1.72
1.759
1.798
1.82
1.8565
1.893
1.9295
1.966
2.0025
2.039
2.0755
2.112
2.1485
2.15
2.17
2.19
2.22
S S t t a a r r t t u u p p
Exhaust Enable
O set
Maximum Fan Speed
-0.2
-0.19
-0.18
-0.17
-0.16
-0.15
-0.14
-0.13
-0.12
-0.11
-0.1
-0.09
-0.08
-0.07
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
0.11
0.12
0.13
0.14
0.15
0.16
0.17
0.18
0.19
0.2
0.21
0.22
0.23
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