Elta T210 Specifications download pdf (Page 88)

PWRM Power Exhaust motors should be set to 1

(4 motors) for the 020-050 units and 2

(6 motors) for the 060 unit

In the CONFIGURATION-BP submenu set the following

variables:

BP.SL Modulating PE Alg Select to 2

BP.S Building Pressure sensor to enable

BP.R Building pressure sensor range to 0.25

BP.HP High BP level to desired value

BP.LP Low BP level to the desired value

OPERATION

The control system has many options and accessories as

well configurable control options. Actual unit operation will

depend on the selected options and set points, but the following

is a general sequence of operation for the basic types of

systems.

Cooling, Constant Volume (CV) Units — On power

up, the control module will activate the initialization software.

The initialization software will determine the unit configura-

tion and also initialize any controls loops and input/output

devices. All configuration settings are maintained in memory

during power outages. All alarms are be maintained in memory

and must be cleared through the Scrolling Marquee display.

CONSTANT VOLUME CONVENTIONAL THERMO-

STAT CONTROL — If the unit is equipped with a conven-

tional thermostat (with Y1, Y2, W1, W2 and G connections)

then the control will perform the following sequence.

When G is closed, the indoor fan will turn on. The G

connection must be closed for heating or cooling to occur. If

the unit is in the occupied mode then the economizer dampers

will be opened to the minimum economizer position. If the unit

is in the unoccupied mode then the economizer dampers will

remain fully closed.

If Y1 is closed, then the control will first check the ability to

use the economizer. If the economizer can be used, based on

the selected changeover configuration, then the control will

modulate the damper open to maintain the low load economiz-

er leaving air temperature set point. If Y2 closes then the

control will lower the leaving air temperature set point to the

configured high load set point. If the economizer cannot satisfy

the load, then compressors will be sequenced on to maintain

either the low or high load temperature set points. If the

economizer cannot be used or the enable control disables the

economizer, then the control will sequence the compressors

based on the Y1, Y2 signals. If two-stage control has been se-

lected, then the control will map the compressors to the Y1, Y2

inputs as defined in the loading sequence. If multistage control

has been selected, then the control will add and remove

compressors stages to maintain the high and low demand set

points. If Y1 is closed, at least one compressor stage will be

turned on.

If W1 closes, then it will indicate that the unit should be in

the heating mode. If the unit is equipped with gas or electric

heat then the first stage of heat will be energized. If W2 closes,

then the control will turn on the second stage of heat. If the unit

is equipped with a staged gas heat control option, then the W1

and W2 signal will be used to control the gas heat to the config-

urable high and low heat load leaving air temperature set

points. If the unit is equipped with gas heat, then the IGC board

will control the operation of the gas heat. See the section on the

IGC board sequence of operation.

CONSTANT VOLUME SPACE SENSOR CONTROL — If

the space temperature operation has been selected by using a

T55, T56, or T58 sensor, then following logic will be used to

control the operation of the unit. If a space temperature sensor

is used, then a wire jumper must be added between R, W1, and

W2 for the heat to operate.

If a remote switch option is being used and configured for

start/stop, then the switch must be closed for the unit to operate.

If the remote switch option has been configured for occupancy,

then the switch will be used to control occupied and unoccu-

pied mode. In the unoccupied mode, the economizer damper

will be positioned to zero unless free cooling is being used. In

the occupied mode, the damper will open to the minimum posi-

tion unless IAQ control is in also being used and then might be

controlled to a lower position. When in the unoccupied mode,

the type of cooling can be configured. If the internal timeclock

function is being used, the start/stop function and occupied and

unoccupied control will be established by the schedules that

have been selected.

There are also some special pre-occupancy modes that may

be used. If Temperature Compensated Start is active, the unit

will be controlled as in the occupied mode and will start at a

time (as determined by prior operation) to have the space at set

point by the occupied time. If the unit has been configured for a

pre-occupancy purge, then the control will start the unit in vent

mode prior to the occupancy time to vent the space. If an IAQ

sensor is being used and the low IAQ set point is satisfied then

the occupancy purge mode will be terminated.

When using the space sensor control option, the set points

for heating and cooling are configurable through the Scrolling

Marquee display. If a T56 sensor is being used, then the set

point can be shifted by as much as 10 degrees. If the space

temperature goes above the cooling set point, then the unit will

go into cooling mode. If the economizer can be used, then the

control will first try to control to the leaving air temperature set

point. The leaving air set point will depend on the space

temperature. If the temperature is above the low demand set

point then the low economizer load discharge air temperature

set point will be used. If the temperature is above the high load

space temperature set point then the high load leaving air

temperature set point will be used. If the economizer cannot

satisfy the load, then compressors will be sequenced on to

maintain either the low or high load temperature set points. If

the economizer cannot be used or the enable control disables

the economizer, then the control will sequence the compressors

based on the high and low load space temperature variables. If

two stage control has been selected, then the control will map

the compressors to the low and high loads as defined in the

loading sequence. If adaptive mode has been selected, then the

control will add and remove compressors stages to maintain

the high and low demand leaving air set points.

If the load goes below the heating space temperature set

point, then it will indicate that the unit should be in the heating

mode. The economizer will be closed to the minimum position

and, if the unit is equipped with gas or electric heat, then the

first stage of heat will be energized. If the space temperature

goes below the high load space temperature set point, then the

control will turn on the second stage of heat. If the unit is

equipped with a staged gas heat control option, then the low

load and high load demand signal will control the leaving

air temperature set point and will turn on heating stages to

maintain the leaving air temperature set points.

If the units is configured for unoccupied free cooling,

mechanical cooling, or heating and the temperature goes

beyond the unoccupied configuration set points then the

control will turn on free cooling, mechanical cooling, or heat as

need to return within the unoccupied set points. When in this

mode, the economizer dampers will be maintained fully closed

or to the minimum unoccupied ventilation set point.

Variable Air Volume Control — On power up, the

control module will activate the initialization software. The

initialization software will determine the unit configuration and

also initialize any controls loops and input/output devices. All

configuration settings are maintained in memory during power

outages. All alarms will be maintained in memory and must be

cleared through the Scrolling Marquee display.

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Elta T210 Specifications Page 88

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