System Selection Procedure; Capacities And Selection Data; Selection Guide - Hitachi FSG1 Series Technical Catalogue

CAPACITIES AND SELECTION DATA

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4.1. SYSTEM SELECTION PROCEDURE

The following system procedure is giving a sample
regarding unit selection system, indicating how to use all
parameters showed in this chapter.
4.1.1. SELECTION UNIT FEATURES
Considering the building distribution, the possible indoor unit
position and the available air flow distribution, select the unit
features that is giving the best efficiency and comfort to
each room.
Decide the Outdoor Unit position getting easy service
maintenance and easy refrigerant pipe installation.
Use the information showed in the following subchapters:
§ For Operation Space possibilities: Subchapter 4.2
Operation Space.
§ For Air Flow distribution: Subchapter 4.10 Temperature
Distribution Diagrams.
§ For Noise Characteristics: Subchapter 4.11 Sound Data
§ For Outdoor Unit position: Subchapter 4.2.8 Outdoor Unit
§ For CH-Box position: Chapter 12.9.2
§ Piping length and lift range: Chapter 13
If duct type unit is selected, the fan performance for duct
calculation should be considered, as Subchapter 4.9 shows.
The units are designed with three possible static pressure
ranges in order to adapt it to all installation necessities.
As indicated in chapter 1, the Set-Free system enable the
outdoor unit to be up to 30% smaller capacity when
compared with the current split Air Conditioning systems.
The diagram shows a typical building with a morning peak
heat load on the east zone equivalent to a 6HP unit.
In the afternoon a peak occurs on the west zone equivalent
to a 7HP unit.
Therefore, a conventional system would require total
installed plant of 6HP + 7HP = 13HP. The maximum
simultaneous load on the whole building occurs at noon and
is equal to 10HP of unit capacity. A Set-Free System of
10HP can therefore be selected, and this capacity can be
directed either to the east or west zone as dictated by the
system controls.
Saving in installed plant = (6.5-5) / 6.5 x 100 = 23%!!!
Example of Air Conditioning for Building
Load of East Zone
Total Load
Load of West Zone
Time
Therefore, the maximum indoor unit capacity combined with
outdoor unit should be carefully considered for correct
indoor unit distribution at each building
For three pipes systems, FXG, the units distribution is more
flexible, because of each indoor unit can operate at different
mode, cooling or heating. At the same time, is possible to
combine several indoor units with the same CH-Box when
all the space need the same operation mode, or all indoor
units will be used in the same room, in order to get better Air
flow distribution. Do not forget to consider that option during
installation design.
4.1.2.

SELECTION GUIDE

The following example is giving the method for indoor and
outdoor units selection of Set-Free system. The same
system can be used for FSG, FSG1, FXG and FXG1.
*
Step 1: Determine the system requirements
Calculate the cooling capacity and heating capacity of each
indoor unit according to the following conditions:
Total Load for each room
Item 1
Estimated
kW 2.75
Cooling Load
Estimated
kW 2.90
Heating Load
Temperature Condition
Cooling
Outdoor Air Inlet
Dry Bulb: 30.0ºC
Indoor Air Inlet
Dry Bulb: 27,0ºC
Wet Bulb: 19.5ºC
Equivalent piping length between Outdoor unit
and farther Indoor unit
Piping Lift between Outdoor Unit and Indoor
Unit
Room
2 3 1+2+3
4.24 5.35 12.34
4.60 6.00 13.50
Heating
Outdoor Air Inlet
Dry Bulb: -1ºC
Wet Bulb: 0ºC
Indoor Air Inlet
Dry Bulb: 20ºC
60 m
25 m