Emerson E2 User Manual download pdf (Page 194)

11-52 • E2 RX/BX/CX I&O Manual 026-1610 Rev 13 14-SEP-2011

11.21.5.1 Bypass Failsafe

While each zone is bypassed to ON, a timer is checked.

If time has elapsed equal to or greater than the zone’s

cycle duration parameter, the bypass input will be ignored

and the zone will return to normal operation.

For a zone in Bypass Failsafe, its bypass input must be

set to OFF or NONE to reset the Bypass Failsafe and to

use the bypass input again.

11.21.6 Flow Sensor-Related Tests

11.21.6.1 Leak Test

For both Timed and Volume control types, if a flow

sensor is configured, water flow will be checked via a leak

test that is performed at the beginning of the cycle. During

the leak test the main water valve will be turned ON and

all zone valves will be set to OFF. After an amount of time

has elapsed equal to the Flow Alarm Delay, the Water

Flow input will be compared to the Minimum Flow for

Alarm setpoint. If the water flow is greater than the set-

point, the flow alarm output will be set to ON and a Leak

alarm will be generated. If a Leak alarm occurs the cycle

will terminate. While a Leak alarm is active, no normal

cycles will run and the system status will be set to Leak

Detected.

A Leak alarm must be cleared by the user or the alarm

will return to normal after passing a leak test run by a

manual cycle. If an enabled zone is overridden to ON dur-

ing a leak test, it will cause the test to fail, resulting in a

false alarm.

11.21.6.2 Obstructed Zone Test

When a zone becomes active during a cycle, a timer is

reset. After time has elapsed equal to the flow alarm delay,

the water flow input will be compared to the Min Flow

alarm setpoint. If the water flow is less than the setpoint,

the flow alarm setpoint output will be set to ON, an

Obstructed alarm generated, and the zone will be removed

from the current cycle.

11.21.7 Service Modes

The Service Check cycle allows a service technician to

visually look for malfunctioning valves and leaks by

cycling each zone ON one at a time, starting with the first

zone. The active zone uses the Service On Time parame-

ter and remains ON for the programmable time period

entered for Service On Time.

While in the Service Check cycle, any active irrigation

cycles will be terminated. The Service Check cycle will

continue looping until stopped by the user or the program-

mable value in the Suspnd Failsafe field is reached.

11.21.8 Heat Cut In/Cut Out Set-

points For Each Stage

If the current space temperature is greater than or equal

to the heat stage Cut Out setpoint, or the individual cool-

ing stage is currently ON due to a call for cooling (Cut In

setpoint or dehumidification), and the current space tem-

perature is greater than the individual COOL stage Cut In

setpoint, then begin turning the stage OFF by starting the

heat stage Off Delay countdown timer.

Or if the current space temperature is less than or equal

to the heat stage Cut In setpoint, begin turning the stage

ON by starting the heat stage On Delay countdown timer.

11.21.9 Cool Cut In/Cut Out Set-

points For Each Stage

If the current space temperature is less than or equal to

the cool stage Cut Out setpoint, begin turning the cool

stage OFF by starting the cool stage Off Delay countdown

timer. If the current space temperature is greater than or

equal to the Cut In setpoint, begin turning the cool stage

ON by starting the cool stage On Delay countdown timer.

11.21.10 Dehumidification Control

Dehumidification control is implemented on an AHU

basis, not individual cooling or heating stages. Because of

implementation on an AHU basis, dehumidification con-

trol is “woven” throughout the cool Cut In/Cut Out as well

as the heating Cut In/Cut Out control algorithms by calling

for increases or decreases in heating and cooling capaci-

ties. The dehumidification algorithm does not directly

change the states of the heating or cooling, instead it

“influences” the staging process by calling for more, less,

or the same amount of cooling, and limit the amount of

heat used if a call for heating is necessary during dehumid-

ification.

If the current space temperature is less than the dehu-

midification minimum space temperature, call for the end

of dehumidification.

If the current control value used for dehumidification

is greater than the dehumidification setpoint plus the dead-

band divided by two (2), call for an increase in dehumidi-

fication capacity.

If the current control value used for dehumidification

is less than the dehumidification setpoint minus the dehu-

midification deadband divided by two (2), call for a

decrease in dehumidification capacity.

11.21.11 Two Speed Fan Control

To determine proper fan speed, determine which heat-

ing and cooling stages are ON and if the user has set any

of the fan speeds for those stages to High. If any of the

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Emerson E2 User Manual Page 194

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