Carrier AquaForce 30XBE 250 User Manual

67
9.6 - Operating limits for changeover between
modes
From cooling only to heat reclaim and vice versa.
Heat reclaim condenser water temperature
°C Minimum Maximum
Water entering temperature 12,5 57,5
Ambient operating
temperature
-10
(1)
45
(1) -20 °C with winter operation option (option 28)
9.7 - Flow control
The water ow switch supplied needs to be installed at the heat
reclaim condenser water inlet and protects the conden-ser loop
against low water ow conditions. When the heat reclaim mode is
required, a signal from the additional board output activates the
system pump. Once the pump is started, ow detection takes place
for one minute. If no ow is detected by the end of this time:
1. Changeover to the heat reclaim mode is not permitted
2. Mode is changed to cooling only mode when the water ow
rate is low, accompanied by a water ow detection alarm.
3
4
6
5
10
11
9
8
10
7
3
4
6
5
10
11
9
8
10
7
12
12
1
2
Legend
1 Evaporator
2 Heat reclaim condenser
3 Air condenser (coils)
4 Compressor
5 Expansion device (EXV)
6 Motorised valve - heat reclaim mode
7 Motorised valve - cooling only mode
8 Solenoid valve - charge recovery in heat reclaim mode
9 Solenoid valve - charge recovery in cooling only mode
10 Check valve
11 Pressure and temperature measurement to calculate the liquid sub-cooling to
optimise the charge recovery
12 Check valve with capillary
9.8 - Heat reclaim operation
The heat reclaim condenser option is only available on units with
two circuits. It has been designed with one or two single or two-circuit
shell-and-tube heat exchangers, depending on the unit size.
The two circuits are independently controlled. One circuit can be
in cooling only and the other in heat reclaim mode.
Changeover from one mode to the other (changeover from heat
exchange at the air condenser to heat exchange at the water
condenser and vice versa) is ensured by motorised two-way valves
located upstream of the air and water condensers.
ATTENTION: Mode changes may lead to higher sound levels
than the levels at stable operation.
Depending on the mode selected (heat reclaim or cooling), the
logic compares the water entering temperature required with the
setpoint. Depending on this di󰀨erence the unit circuits are either
activated or deactivated in heat reclaim mode (one or two together),
as shown in the following diagram and table.
A
B
C
D
E
+2,5 K
+1,25 K
-1,25 K
-2,5 K
T
Setpoint, °C
Condenser water entering
temperature
Deadband
E
A
B
C
D
-1.25 K
-2.5 K
+2.5 K
+1.25 K
The deadband of 5 K is controlled by default.
Case
Selection of the
heat reclaim mode
Number of circuits
in heat reclaim mode
Action
- NO 0
+ 2 circuits in
cooling mode
A YES Whatever the number
+ 2 circuits in heat
reclaim mode
B YES 0
+ 1 circuit in heat
reclaim mode
1 No change
2 No change
C YES Whatever the number No change
D YES 1 No change
2
- 1 circuit in heat
reclaim mode
E YES Whatever the number
- 2 circuits in heat
reclaim mode
For more details on the heat reclaim operation logic please refer
to the SmartVu
TM
control manual, chapter 6.15 - “Optional heat
reclaim module”.
9.9 - Condenser pump selection
Heat reclaim condenser water ow rate/pressure drop
Heat reclaim condenser pressure drop in water ow
rate function
0
10
20
30
40
50
60
70
010203
04
0
Pressure drop, kPa
Water ow rate, l/s
1 Condenser 10” (water volume = 38 litres)
2 Condenser 12” (water volume = 55 litres)
3 Condenser 14” (water volume = 68 litres)
For units with a water condenser please refer to chapter 9.1 - “Technical data, 30XB
units with heat reclaim condenser option”.
9 - HEAT RECLAIM CONDENSER OPTION (OPTION 50)

Carrier AquaForce 30XBE 250 Specifications

General

Brand	Carrier
Model	AquaForce 30XBE 250
Category	Chiller
Language	English