Carrier AQUAZONE PSV - Manual (Page 46)

46
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
controller (UC) open loop controller. Loop pump operation is
automatically controlled by WSHP equipment occupancy
schedules, 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
unoccupied heating or cooling demand, or a tenant pushbutton
override. At each WSHP, the water loop temperature and the
loop pump status is given. The WSHP will NOT start a com-
pressor until the loop pumps are running or will shutdown the
compressors should the pumps stop. This prevents the WSHP
from operating without water flow and thus tripping out on re-
frigerant 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 opera-
tion (from 1-"N"). This can be used to prevent starting the en-
tire loop operation 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
Test mode provides the ability to check the control opera-
tion in a timely manner. The control enters a 20-minute test
mode by momentarily shorting the test terminals. All time de-
lays are sped up 15 times. The follow operations are common
to both Complete C and Deluxe D controls.
Test Mode — To enter Test mode, cycle the power 3 times
within 60 seconds. The LED 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 34 and 35.
To exit Test mode, short the terminals for 3 seconds or cycle
the power 3 times within 60 seconds.
NOTE: The flashing code and alarm relay cycling code will
both have the same numerical label. For example, flashing
code 1 will have an alarm relay cycling code 1. Code 1 indi-
cates the control has not faulted since the last power off to
power on sequence.
Table 34 — Complete C Control Current LED
Status and Alarm Relay Operations
LEGEND
NOTES:
1. Slow flash is 1 flash every 2 seconds.
2. Fast flash is 2 flashes every 1 second.
3. EXAMPLE: “Flashing Code 2” is represented by 2 fast flashes followed by a
10-second pause. This sequence will repeat continually until the fault is cleared.
°
°
°
°
LED STATUS DESCRIPTION OF OPERATION ALARM RELAY
On
Normal Mode Open
Normal Mode with PM Warning
Cycle (closed 5 sec.,
open 25 sec.)
Off Complete C Control is non-functional Open
Slow Flash Fault Retry Open
Fast Flash Lockout Closed
Slow Flash Over/Under Voltage Shutdown
Open, (Closed after
15 minutes)
Flashing Code 1 Test Mode — No fault in memory Cycling Code 1
Flashing Code 2 Test Mode — HP Fault in memory Cycling Code 2
Flashing Code 3 Test Mode — LP Fault in memory Cycling Code 3
Flashing Code 4 Test Mode — FP1 Fault in memory Cycling Code 4
Flashing Code 5 Test Mode — FP2 Fault in memory Cycling Code 5
Flashing Code 6 Test Mode — CO Fault in memory Cycling Code 6
Flashing Code 7
Test Mode — Over/Under
shutdown in memory
Cycling Code 7
Flashing Code 8 Test Mode — PM in memory Cycling Code 8
Flashing Code 9
Test Mode — FP1/FP2
Swapped Fault in memory
Cycling Code 9
CO — Condensate Overflow LED — Light-Emitting Diode
FP — Freeze Protection LP — Low Pressure
HP — High Pressure PM — Performance Monitor