Specifications

54
Table 62 — Economizer Run Status Table
Building Pressure Control — This control sequence
provides control of the building pressure through the modulat-
ing flow rate function of the modulating power exhaust option.
This function also provides control of the constant volume
2-stage power exhaust option.
BUILDING PRESSURE CONFIGURATION — The build-
ing pressure configurations are found at the local display under
Configuration
→ BP. See Table 63.
Building Pressure Config (
BP.CF) — This configuration se-
lects the type of building pressure control.
• BP.CF = 0, No building pressure control
• BP.CF = 1, constant volume two-stage exhaust based on
economizer position
• BP.CF = 2, Modulating building pressure control
Power Exhaust Motors (
BP.MT) — This configuration is ma-
chine dependent and instructs the building pressure control
algorithm as to whether the unit has 4 or 6 motors to control.
The motors are controlled by three power exhaust relays A, B,
and C. These relay outputs are located at the local display un-
der Outputs
→ FAN S → PE.A,B,C.
The following table illustrates the number of motors each
relay is in control of based on BP.MT:
Building Pressure Sensor (
BP.S) — This configuration al-
lows the reading of a building pressure sensor when enabled.
This is automatically enabled when BP.CF =2.
Building Pressure (+/–) Range (
BP.R) — This configuration
establishes the range in in. wg that a 4 to 20 mA sensor will be
scaled to. The control only allows sensors that measure both
positive and negative pressure.
Building Pressure SETP (
BP.SP) — This set point is the
building pressure control set point. If the unit is configured for
modulating building pressure control, then this is the set point
that the control will control to.
Power Exhaust on Setp.1 (
BP.P1) — When configured for
building pressure control type BP.CF = 1 (constant volume two-
stage control), the control will turn on the first power exhaust
fan when the economizer’s position exceeds this set point.
Power Exhaust on Setp.1 (
BP.P2) — When configured for
building pressure control type BP.CF = 1 (constant volume two-
stage control), the control will turn on the second power exhaust
fan when the economizer’s position exceeds this set point.
Modulating PE Algorithm Select (
BP.SL) — This configuration
selects the algorithm used to step the power exhaust stages. This
must be set to 1 at all times. The other selections are not used.
Building Pressure PID Evaluation Time (
BP.TM) —This
configuration is the run time rate of the multiple stage (modu-
lating) power exhaust algorithm.
Building Pressure Threshold Adjustment (
BP.ZG) —This
configuration is not used. It currently has no effect on building
pressure control.
High Building Pressure Level (
BP.HP) — This configura-
tion is the threshold level above the building pressure set point
used to control stages of power exhaust when BP.SL=1.
Low Building Pressure Level (
BP.LP) — This configuration
is the threshold level below the building pressure set point used
to control stages of power exhaust when BP.SL=1.
CONSTANT VOLUME 2-STAGE CONTROL (BP.CF =1)
OPERATION — Two exhaust fan relays will be turned on and
off based on economizer position. The two trip set points are
BP.P1 and BP.P2. If the economizer is greater than or equal
to BP.P1, then power exhaust stage 1 is requested and a
60-second timer is initialized. If the economizer is 5% below
the BP.P1, then power exhaust stage 1 is turned off. Also, if the
economizer position is less than BP.P1 and the 60-second timer
has expired, power exhaust stage 1 is turned off. The same
logic applies to the second power exhaust stage, except the
BP.P2 trip point is monitored. If the economizer position is
greater than or equal to BP.P2, then power exhaust stage 2
is energized and a 60-second timer is initialized. If the econo-
mizer is 5% below the BP.P2 the second power exhaust
stage turned off. If the economizer is less than BP.P2 and the
60-second timer has expired, second stage power exhaust is
turned off.
For BP.CF=1, the Table 64 illustrates the power exhaust
stages 1 and 2, relay combinations based upon Configuration
→ BP.MT (4 or 6 motors).
MULTIPLE POWER EXHAUST STAGE BUILDING
PRESSURE CONTROL (BP.CF =2)OPERATION—
Building pressure control is active whenever the supply fan is
running. The control algorithm to be used (BP.SL=1)isatimed
threshold technique for bringing stages of power exhaust on
and off.
The number of power exhaust stages available for this con-
trol algorithm is a function of the number of motors it supports.
This number of motors is defined by the Configuration
→ BP
→ BP.MT configuration. Table 65 illustrates the staging tables
for this control algorithm based on BP.MT.
ITEM EXPANSION RANGE UNITS CCN POINT WRITE STATUS
ECN.P Economizer Act.Curr.Pos. 0-100 % ECONOPOS
ECN.C Economizer Act.Cmd.Pos. 0-100 % ECONOCMD forcible
ACTV Economizer Active ? YES/NO ECACTIVE
DISA ECON DISABLING CONDITIONS
UNVAV Econ Act. Unavailable? YES/NO ECONUNAV
R.EC.D Remote Econ. Disabled? YES/NO ECONDISA
DBC DBC - OAT Lockout? YES/NO DBC_STAT
DEW DEW - OA Dewpt.Lockout? YES/NO DEW_STAT
DDBC DDBD- OAT > RAT Lockout? YES/NO DDBCSTAT
OAEC OAEC- OA Enth Lockout? YES/NO OAECSTAT
DEC DEC - Diff.Enth.Lockout? YES/NO DEC_STAT
EDT EDT Sensor Bad? YES/NO EDT_STAT
OAT OAT Sensor Bad ? YES/NO OAT_STAT
FORC Economizer Forced ? YES/NO ECONFORC
SFON Supply Fan Not On 30s ? YES/NO SFONSTAT
CLOF Cool Mode Not In Effect? YES/NO COOL_OFF
OAQL OAQ Lockout in Effect ? YES/NO OAQLOCKD
HELD Econ Recovery Hold Off? YES/NO ECONHELD
O.AIR OUTSIDE AIR INFORMATION
OAT Outside Air Temperature dF OAT forcible
OA.RH Outside Air Rel. Humidity % OARH forcible
OA.E Outside Air Enthalpy OAE
OA.D.T Outside Air Dewpoint Temp dF OADEWTMP
BP.MT PE_ARelay PE_BRelay PE_CRelay
1(4motors) 1 Motor 2 Motors 1 Motor
2(6motors) 1 Motor 2 Motors 3 Motors