Carrier AQUAZONE 50PEC09-18 User Manual

Page 43

ASHRAE (American Society of Heating, Refrigerating and

Air Conditioning Engineers) specifications by providing a base

ventilation rate and then increasing the rate as the CO

level in-

creases. The control will begin to proportionally increase venti-

lation when the CO

level rises above the start ventilation set

point and will reach the full ventilation rate when the CO

level

is at or above the maximum set point. A user-configurable min-

imum damper position ensures that proper base ventilation is

delivered when occupants are not present. The IAQ configura-

tions can be accessed through the configuration screen. The

following conditions must be true in order for this algorithm to

run:
• Damper control is configured for DCV.

• The unit is in an occupied mode.

• The IAQ sensor reading is greater than the DCV start

control set point.
The control has four user adjustable set points: DCV start

control set point, DCV maximum control set point, minimum

damper position, and DCV maximum damper position.
Two-Position OA Damper — The control can be configured

to operate a ventilation damper in a two-position ventilation

mode to provide the minimum ventilation requirements during

occupied periods.
WATERSIDE ECONOMIZER — The WSHP Open control-

ler has the capability of providing modulating or two-position

water economizer operation (for a field-installed economizer

coil mounted to the entering air side of the unit and connected

to the condenser water loop) in order to provide free cooling

(or preheating) when water conditions are optimal. Water econ-

omizer settings can be accessed through the equipment status

screen. The following conditions must be true for economizer

operation:
• SAT reading is available.

• LWT reading is available.

• If occupied, the SPT is greater than the occupied cooling

set point or less than the occupied heating set point and

the condenser water is suitable.

• Space temperature reading is valid.

• If unoccupied, the SPT is greater than the unoccupied

cooling set point or less than the unoccupied heating set

point and the condenser water is suitable.

Modulating Water Economizer Control — The control has

the capability to modulate a water valve to control condenser

water flowing through a coil on the entering air side of the unit.
Cooling — The purpose is to provide an economizer cooling

function by using the water loop when the entering water loop

temperature is suitable (at least 5 F below space temperature).

If the water loop conditions are suitable, then the valve will

modulate open as required to maintain a supply-air temperature

that meets the load conditions. Should the economizer coil ca-

pacity alone be insufficient for a period greater than 5 minutes,

or should a high humidity condition occur, then the compressor

will also be started to satisfy the load. Should the SAT ap-

proach the minimum cooling SAT limit, the economizer valve

will modulate closed during compressor operation.
Heating — Additionally, the control will modulate the water

valve should the entering water loop temperature be suitable

for heating (at least 5 F above space temperature) and heat is

required. The valve will be controlled in a similar manner ex-

cept to satisfy the heating requirement. Should the economizer

coil capacity alone be insufficient to satisfy the space load con-

ditions for more than 5 minutes, then the compressor will be

started to satisfy the load. Should the SAT approach the maxi-

mum heating SAT limit, the economizer valve will modulate

closed during compressor operation.
Two-Position Water Economizer Control — The control has

the capability to control a NO or NC, two-position water valve

to control condenser water flow through a coil on the entering

air side of the unit.

Cooling — The purpose is to provide a cooling economizer

function directly from the condenser water loop when the en-

tering water loop temperature is suitable (at least 5 F below

space temperature). If the optional coil is provided and the wa-

ter loop conditions are suitable, then the valve will open to pro-

vide cooling to the space when required. Should the capacity

be insufficient for a period greater than 5 minutes, or should a

high humidity condition occur, then the compressor will be

started to satisfy the load. Should the SAT reach the minimum

cooling SAT limit, the economizer valve will close during

compressor operation.
Heating — Additionally, the economizer control will open the

water valve should the entering water loop temperature be suit-

able for heating (at least 5 F above space temperature) and

heat is required. The valve will be controlled in a similar man-

ner except to satisfy the heating requirement. Should the coil

capacity be insufficient to satisfy the space load for more than

5 minutes, then the compressor will be started to satisfy the

load. Should the SAT reach the maximum heating SAT limit,

the economizer valve will close during compressor operation.
DEMAND LIMIT — The WSHP Open controller has the

ability to accept three levels of demand limit from the network.

In response to a demand limit, the unit will decrease its heating

set point and increase its cooling set point to widen the range in

order to immediately lower the electrical demand. The amount

of temperature adjustment in response is user adjustable for

both heating and cooling and for each demand level. The re-

sponse to a particular demand level may also be set to zero.
CONDENSER WATER LINKAGE — The control pro-

vides optimized water loop operation using an universal con-

troller (UC) open loop controller. Loop pump operation is auto-

matically controlled by WSHP equipment occupancy sched-

ules, unoccupied demand and tenant override conditions.

Positive pump status feedback prevents nuisance fault trips.

The condenser water linkage operates when a request for con-

denser water pump operation is sent from each WSHP to the

loop controller. This request is generated whenever any WSHP

is scheduled to be occupied, is starting during optimal start (for

warm-up or pull down prior to occupancy), there is an unoccu-

pied heating or cooling demand, or a tenant pushbutton over-

ride. At each WSHP, the water loop temperature and the loop

pump status is given. The WSHP will NOT start a compressor

until the loop pumps are running or will shutdown the com-

pressors should the pumps stop. This prevents the WSHP from

operating without water flow and thus tripping out on refriger-

ant pressure, causing a lockout condition. The WSHP Open

controller control will prevent this from occurring. Also, the

loop controller can be configured to start the pumps only after a

configurable number of WSHPs are requesting operation (from

1-"N"). This can be used to prevent starting the entire loop op-

eration for only one WSHP. Meanwhile, the WSHPs will not

operate if the loop pump status is off and therefore the WSHP

compressor will not run.

COMPLETE C AND DELUXE D BOARD

SYSTEM TEST

System testing provides the ability to check the control

operation. The control enters a 20-minute Test mode by

momentarily shorting the test pins. All time delays are reduced

by a factor of 15.

Test Mode —

To enter Test mode on Complete C or

Deluxe D controls, cycle the power 3 times within 60 seconds.

The LED (light-emitting diode) will flash a code representing

the last fault when entering the Test mode. The alarm relay will

also power on and off during Test mode. See Tables 15-17. To

exit Test mode, short the terminals for 3 seconds or cycle the

power 3 times within 60 seconds.
NOTE: The Deluxe D control has a flashing code and alarm

relay cycling code that will both have the same numerical