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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*
45
*
-20 °C with winter operation option (option 28)
9.7 - Flow control
The water flow switch supplied needs to be installed at the
heat reclaim condenser water inlet and protects the conden-
ser loop against low water flow conditions. When the heat
reclaim mode is required, a signal from the additional board
output activates the system pump. Once the pump is started,
flow detection takes place for one minute. If no flow 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 flow rate is low, accompanied by a water flow
detection alarm.
2
3
6
3
6
12
12
9
9
10
10
7
7
11
11
8
8
10
10
5
5
4
4
1
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 difference the unit
circuits are either activated or deactivated in heat reclaim
mode (one or two together), as shown in the following
diagram and table.
E
E
+2,5 K
+2.5 K
D
D
+1.25 K
+1,25 K
Setpoint, °C
C
C
-1,25 K
-1.25 K
B
B
-2.5 K
-2,5 K
A
A
T
The deadband of 5 K is controlled by default.
Case Selection of the
Number of circuits
Action
heat reclaim mode
in heat reclaim mode
-
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 30XA/30XAS/30XW Touch Pilot control manual,
chapter 6.15 - “Optional heat reclaim module”.
9.9 - Condenser pump selection
Heat reclaim condenser water flow rate/pressure drop
Heat reclaim condenser pressure drop in water flow
rate function
70
60
50
40
30
20
10
0
0
10
20
30
40
Water flow 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, 30XA units with heat reclaim condenser option”.
Page 42
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