Carrier 33ZCSECTRM Especificaciones descargar pdf (Pagina 29)

HOT WATER HEAT — The zone controller can be config-

ured to control local heat provided by heating coils carrying hot

water or steam, governed either by a two-position (on/off)

valve or by a proportional (floating modulating) valve. The

heating coils can be installed in the air terminal (ducted), or as

perimeter heat. If modulating baseboard heat is used, refer to

the General Heating Information section for additional infor-

mation. Figure 24 shows the hardware configuration for a zone

controller applied to a parallel fan powered air terminal

equipped with hot water or steam heating coils. The diagram in

Fig. 25 shows how the zone controller controls an air terminal

equipped with two-position hot water or steam heat. The dia-

gram in Fig. 26 shows how the zone controller controls an air

terminal equipped with proportional hot water or steam heat.

The fan runs while the air terminal is heating.

For modulating control, the supply air needed is compared

to the actual supply air to either drive the valve open or closed.

There is a deadband on the supply air deviation where the valve

will be left at the current position until the error gets larger than

the deadband.

Configuration determines the logic output type for normally

open or normally closed type two-position valves.

Heating with IAQ Control

— A feature is provided for situa-

tions in which additional primary air is required for ventilation

(IAQ).

The heating set point is calculated from the midpoint be-

tween the current heating and cooling set points.

The standard heating algorithm is used. The effect is to pre-

vent the space temperature from falling below the set point be-

fore heating is activated. The air terminal must be in the Cool-

ing mode and the equipment must be providing cooling.

When in unoccupied heating, the terminal’s fan will be

turned on to provide airflow to the zone. Also, in the Unoccu-

pied mode, a parallel fan terminal zone controller will keep the

primary damper closed to prevent airflow back into the prima-

ry air duct. If the air source becomes active (on) during this

mode, the damper will be controlled normally.

Static Pressure Reset

OVERVIEW — The static pressure reset function of the zone

controller linkage master will automatically reset the central air

source’s supply-fan static pressure set point (downward) as a

function of the zone damper position. This allows the system to

automatically make adjustments to the static pressure and opti-

mize performance of the central air source fan. The maximum

pressure is determined by the set point configured at the equip-

ment control. The minimum value is determined by the maxi-

mum value configured.

OPERATION — Once a minute, the linkage master examines

the state of the air source fan. If the fan is operating, the posi-

tion of each damper serviced by the air source is polled by the

Linkage Master to determine the position of its dampers. If the

fan is off, the algorithm calculates a value of 0 for the reset

value.

With the fan operating, the static pressure function deter-

mines the maximum open damper in the system and compares

that value to the configured reset minimum damper position.

When all of the dampers are below (closed) the configured re-

set minimum damper position, the linkage master calculates a

reset value.

The reset value is communicated to the fan controller in the

air source once every minute. The central air source controller

subtracts the reset value from the air source static pressure set

point.

The central air source controller begins to modulate its fan

volume control mechanism to maintain the new supply static

pressure set point. Each zone controller modulates its termi-

nal’s damper position in order to provide the required pressure

drop or restriction to maintain the zone’s CFM balance point at

this new supply duct pressure. If the static pressure set point

value has been changed, then the linkage master will wait

2 minutes to allow the air source static pressure control to af-

fect the system static pressure before calculating any further re-

set value. If the most open damper in the system is open greater

than the maximum damper position, then the linkage master

calculates a reduction to the previous reset value. This will re-

sult in an increase in static pressure (never greater than the con-

figured set point).

NOTE: Primary air source controllers that support this func-

tion are the AirManager™ control. Comfort Controllers can

support this function by using Best++™ applications available

by contacting the local Carrier representative.

Indoor Air Quality (IAQ) Control —

Each zone con-

troller used in a single duct and fan powered application has the

ability to provide IAQ operation. The IAQ function determines

the zone ventilation airflow as a function of the IAQ zone sen-

sor reading. When the air quality control is enabled, the zone

controller will override (increase) the primary airflow in order

to provide Demand Controlled Ventilation if the airflow is in-

sufficient to meet the ventilation set point.

The control algorithm uses a P/I algorithm to determine the

required airflow in order to prevent the IAQ sensor value from

exceeding the desired Air Quality set point. The zone controller

is designed to interface with the following IAQ sensors that

sense CO

The 33ZCSENCO2 sensor is an indoor, wall mounted sen-

sor with an LED (light-emitting diode) display. The sensor has

an analog output (0 to 10 vdc) over a range of 0 to 2000 ppm.

An SPDT contact is provided to close at 1000 ppm with a hys-

teresis of 50 ppm.

The 33ZCT55CO2 sensor is an indoor, wall mounted

sensor without display. The CO

sensor also includes a space

temperature sensor with override button.

The 33ZCT56CO2 sensor is an indoor, wall mounted

sensor without display. The CO

sensor also includes a space

temperature sensor with override button and temperature

offset.

The IAQ function contains a provision to operate modulat-

ing type heat, if required and supplied, to maintain the space

temperature at the midpoint between the heating and cooling

set points during IAQ operation. Operation is dependent upon

the equipment mode of operation, so that the Air Quality func-

tion will only operate during Occupied periods when the out-

door air damper is actively providing ventilation. A user con-

figured AQ Maximum % can be used to protect the zone from

overcooling if local heating is not supplied. Air Quality control

is automatically suspended if the space temperature falls below

the heating set point. Air quality control will be disabled if the

AQ sensor status fails.

Secondary Zone Controller (33ZCSECTRM) —

The 33ZCFANTRM zone controller, in conjunction with the

33ZCSECTRM zone controller, can be used for zone pressure

control and dual duct applications. To perform these functions

a secondary damper and a secondary airflow sensor is required.

The type of secondary airflow control (none, pressurization, or

dual duct) is user selectable at each secondary zone controller.

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Carrier 33ZCSECTRM Especificaciones Pagina 29

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