Carrier 33ZCVAVTRM Spezifikationen PDF herunterladen (Seite 27)

Ducted Heat Control (Staged or Modulating

Device) —

The zone controller can support a ducted heat

function. The ducted heat function can be configured for either

single duct units, fan powered parallel, or fan powered series

applications where heat needs to be controlled within the zone

that is supplied by the terminal unit.

For this application, heating control loop feedback is re-

quired. The installation of the supply air sensor is required

when the unit is configured for ducted heat.

The zone controller can control a single stage, two-position,

multistage electric heat, or a modulating hot water valve.

When the 33ZCVVTZC-01, 33ZCVAVTRM, or

33ZCFANTRM zone controllers are applied and configured

for heat, and heating is being called for in the space, the zone

controller reads the space sensor and the output is adjusted to

satisfy conditions. The number of stages (if applicable) is

determined by comparing space temperature with the current

biased heating set point.

Configuration determines the logic output type for normally

open or normally closed type two-position valves.

A terminal unit equipped with heating will provide the min-

imum heating cfm configured for the zone whenever the air

source is in heat mode unless VAV central heating is enabled.

The heating control maintains the current heating set point

(plus any offset from a 33ZCT56SPT sensor slide bar during

occupied periods).

Modulating Hot Water/Steam Valve CV — The

Modulating Hot Water/Steam Valve CV mode is designed to

use modulating heat valve with a constant volume airflow. This

mode of operation allows all cfm set points to be set to the

same cfm value. The zone reheat will temper the supply air to

maintain proper zone temperature at the configured constant

volume of air.

Central Heating — The use of the zone controller in a

system allows for the application of heating utilizing the heat

from a central air source. The zone controller provides the abil-

ity to add heat to a system during the occupied mode from a

central source. Terminal units designed without any local heat

(ducted or non ducted), should utilize heating. During heating,

the zone controller modulates its primary air damper to provide

heat when the air source is in Heat Mode. The airflow is con-

trolled so that the zone achieves and maintains the desired heat-

ing set point.

NOTE: Central heating is always set to YES on VVT® zone

controllers. No central heating configuration is available if it is

changedtoNO.

In central heating, the terminal provides a variable volume

into the zone. The central supply air will be a source of heating

when the air source is in the heating mode.

For pressure independent applications, the zone controller

temperature control loop determines the airflow set point that is

required to maintain space temperature at the heating set point.

Each zone controller modulates between the minimum heating

cfm and the maximum heating cfm during central heating. This

cfm should be limited to a configured range of values that al-

lows the air source to operate properly in the heating mode.

For pressure dependent applications, the minimum and

maximum damper positions are used to maintain the space

temperature during central heating.

In a system with a Linkage compatible air source, the

zone controller will notify the corresponding linkage coordina-

tor zone controller that the unit is Heat mode.

In the case of a non-Linkage compatible air source, the zone

controller should be set up as the linkage coordinator for

that air source. The zone controller will determine if the

primary-air temperature is greater than the weighted average

space temperature, and if higher, then declares the central air

source in heating.

VAV Central Heating with Ducted Zone Heat

(PI Only) —

When heating is available at the zone (ducted),

and central heating is also available, the zone heat will work in

parallel to provide heating to the space. This heating function

provides the required volume of heated air from the central

apparatus. This volume is determined by a PID airflow control,

the space temperature, and the desired set point. In addition, the

temperature of the air can be supplemented by the local heat

source, if the current air temperature cannot meet zone require-

ments. Each zone controller configured for heat (ducted or non

ducted) will operate its heating control loop when ever the

space temperature is below the heating set point to determine a

desired supply air discharge temperature that is necessary to

maintain space temperature at the heating set point.

NOTE: Central heat with ducted zone heat requires a supply

air sensor.

Damper Override — Damper Override mode is initiat-

ed by the air source in response to input from a field-supplied

smoke control panel. When the air source enters an override

mode the linkage coordinator signals the zone controllers to

take corresponding action. The override can take either of two

forms: pressurization or evacuation. In Pressurization mode,

the zone controller commands the air terminal’s supply air

damper to maximum cool cfm. In Evacuation mode, it com-

mands the damper completely closed.

Damper Override supersedes the cfm setting the zone con-

troller would otherwise maintain based on space temperature.

The smoke control panel that commands the override mode

must be in accordance with local codes, as must its installation.

When using central heating, it is the system designer’s

responsibility that the central apparatus is protected during

heating to provide proper airflow over the central heating

device. Ensure that there will be a minimum system air-

flow that will allow the air source to operate safely in the

heating mode. The zone controller (pressure independent

only) will allow for the option of disabling the central heat-

ing function in a given zone. This means that a central air

source may provide heating for the entire system, or possi-

bly only provide it for those terminals without heat at the

zone level.

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