Units With Fans With Available Pressure For Indoor Installation (Option 12) - Carrier AquaSnap 30RB Series Installation, Operation And Maintenance Instructions

Nominal conditions corresponding to coefficient = 1
Evaporator entering/leaving temperature = 12/7°C
Desuperheater entering/leaving temperature = 50/60°C
Condenser entering air temperature = 35°C (curve B)
11.4 - Units with fans with available pressure for
indoor installation (option 12)
This option applies to 30RB units installed inside the
building in a plant room. For this type of installation the
hot air leaving the air-cooled condensers is discharged by
the fans to the outside of the building, using a duct system.
The installation of a duct system at the air condenser
discharge line causes a pressure drop due to the resistance
caused by the air flow.
Therefore more powerful fan motors than those used for
the standard units are installed in this option. For each
installation of a unit installed inside a plant room the duct
pressure drops differ, depending on the duct length, duct
section and direction changes.
30RB units equipped with fans with available pressure are
designed to operate with air discharge ducts with maximum
pressure drops of 200 Pa.
To compensate for these pressure drops 30RB units with
option 12 are equipped with variable-speed fans with a
maximum speed of 19 r/s, instead of 15.8 r/s and fixed-speed
fans as for the standard units.
Use of variable speed up to 19 r/s can overcome the duct
pressure drops while maintaining an optimised air flow per
circuit. All fans in the same circuit, operating at the same
time, have the same speed.
The maximum fan power input for fans with a speed of 19
r/s is increased compared to that of standard fans with a
speed of 15.8 r/s (the coefficient is the same as the cube of
the speed ratio i.e. x 1.72).
The full-load or part-load speed is controlled by a patented
algorithm that permanently optimises the condensing
temperature to ensure the best unit energy efficiency
(EER) whatever the operating conditions and pressure
drops of the system ductwork.
If necessary for a specific installation, the maximum fan
speed of 30RB units can be fixed between 13 and 19 r/s,
using the Service Configuration menu. Consult the 30RB
Pro-Dialog control manual for this modification.
Operating conditions
Curve No. Outside temperature, °C
1 25
2 25
3 Eurovent 35
4 45
5 45
The unit cooling capacity and energy efficiency ratio (EER)
varies depending on the duct pressure drops:
- between 0 and 100 Pa the unit cooling capacity is only
slightly affected,
- between 100 and 200 Pa the unit cooling capacity falls
considerably depending on the operating conditions
(outdoor air temperature and water conditions).
Please refer to the curves below to evaluate the impact of
the estimated duct system pressure drop for the installation
and the impact of different full load operating conditions
on the 30RB unit cooling capacity and EER.
Cooling capacity variations for operating conditions
EER variations for operating conditions that differ
Entering water temperature, °C
15
10
12
15
10
that differ from Eurovent conditions
Duct pressure drop, Pa
from Eurovent conditions
Duct pressure drop, Pa
leaving water temperature, °C
10
5
7
10
5
load, %
100
100
100
100
100
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