Carrier AQUASNAP 30RQ Installation, Operation And Maintenance Instructions page 31

11.1.4 - Installation
The water supply of each desuperheater is arranged in parallel.
The water connections on the desuperheater water inlets and
outlets must not cause any mechanical local constraint at the
heat exchangers. If necessary, install flexible connection
sleeves.
Install water flow control and balancing valves at the heat
exchanger outlet. Water flow control and balancing can be done
by reading the pressure drop in the heat exchangers. This
pressure drop must be identical on all of them with the total
water flow rate given by the "Electronic catalogue" selection
program.
Please refer to the pressure drop curves below to carry out the
control of the balancing valves before starting up the installation.
It is possible to refine the water flow control of each desuperheater
when the unit operates at full load by trying to obtain leaving
water temperatures that are absolutely identical for each circuit.
Desuperheater (plate heat exchanger pressure drop
100
10
A
1
0.28 (1)
1
Heat exchanger water flow rate, l/s (m
A Circuit with two compressors
B Circuit with three compressors
C Circuit with four compressors
curves)
C
B
2.78 (10) 8.33 (30)
10
/h)
3
Operation of the pump (see typical diagram - item 20 of chapter
11.1.3) of the desuperheater water circuit can be linked to the
start-up of the first unit compressor. This requires the installation
of an additional electronic board in the control box: option 156,
Energy Management Module.
Output No. 25 of the additional board of this option allows
control of the pump operation - the pump will start up when the
unit starts.
A flow switch (item 29) can be installed to generate an alarm if
there is a problem with the pump.
The volume of the desuperheater circuit water loop must be as
low as possible so that the temperature can increase rapidly
when the unit is started up. The minimum entering water
temperature at the desuperheater is 25°C. This may require the
use of a three-way valve (item 31), with a controller and the
sensor controlling the minimum required entering water
temperature.
The desuperheater water loop must include a safety valve and
an expansion tank. When selecting these, consider the water
loop volume and the maximum temperature (120°C) when
pump operation is stopped (item 20).
11.1.5 - Operating range
Cooling mode
Water heat exchanger (evaporator)
Entering water temperature at start-up*
Leaving water temperature during operation °C
Entering water temperature at shut-down
Desuperheater
Entering water temperature at start-up**
Leaving water temperature during operation °C
Entering water temperature at shut-down
Air heat exchanger (condenser)
Entering air temperature***
Available static pressure
Heating mode
Water heat exchanger (condenser)
Entering water temperature at start-up
Leaving water temperature during operation °C
Entering water temperature at shut-down
Desuperheater
Entering water temperature at start-up**
Leaving water temperature during operation °C
Entering water temperature at shut-down
Air heat exchanger (evaporator)
Entering air temperature
Available static pressure
Note: Do not exceed the maximum operating temperature.
* For an application that requires operation below 6.8°C, contact Carrier.
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** The entering water temperature at start-up must not be lower than 25°C. For
installations with a lower temperature a three-way valve is necessary.
** For operation down to -20°C the unit must be equipped with option 28
(winter operation). In addition the unit must either be equipped with the frost
protection option or the water loop must be protected by the installer by
adding a frost protection solution.
Maximum outside temperatures: During storage and transport of the 30RQ
units the minimum and maximum temperatures must not exceed -20°C and
+48°C. It is recommended to observe these temperatures during transport by
container.
Minimum Maximum
°C 6.8* 30
5 15
°C - 60
°C 25 60
30 80
°C 3 60
°C 0 46
Pa 0 0
Minimum Maximum
°C 8 45
20 50
°C 3 60
°C 25 60
30 80
°C 3 60
°C -10 35
Pa 0 0
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