Engineering Manual

Qidu(combi) = Qodu(rated) x Qidu(rated)
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EQUIPMENT SELECTION PROCEDURE
Using the System Combination Tables
Multi F system combination tables illustrate how each indoor unit receives a percentage of total outdoor unit rated capacity. Allocation is
based on:
• Combinations of Non-Ducted Indoor Units
• Combinations of Ducted Indoor Units
• Combinations of Mixed Non-Ducted and Ducted Indoor Units
Multi F MAX system combination tables only show the total connected indoor unit capacity, but individual indoor unit capacity can be
calculated using the formula:
A more accurate method to determine expected capacity would be to apply the outdoor unit’s corrected capacity instead of rated capacity.
Table 92: Multi F Outdoor Unit (Multiple Piping) to Indoor Unit Refrigerant Line Length Derates.
Piping Length (feet) Cooling Capacity (%) Heating Capacity (%)
7,000 Btu/h Indoor Unit Models
25.0 100.0 100.0
32.8 98.4 99.2
49.2 95.8 97.8
65.6 93.2 96.4
82.0 90.6 95.0
9,000 Btu/h Indoor Unit Models
25.0 100.0 100.0
32.8 98.0 99.0
49.2 94.8 97.4
65.6 91.6 95.8
82.0 88.4 94.2
12,000 Btu/h Indoor Unit Models
25.0 100.0 100.0
32.8 97.6 98.6
49.2 93.8 96.4
65.6 89.9 94.1
82.0 86.1 91.9
15,000 Btu/h Indoor Unit Models
25.0 100.0 100.0
32.8 97.2 98.2
49.2 93.0 95.4
65.6 88.8 92.6
82.0 84.6 89.8
18,000 Btu/h Indoor Unit Models
25.0 100.0 100.0
32.8 98.6 99.6
49.2 96.4 99.0
65.6 94.1 98.3
82.0 91.9 97.7
24,000 Btu/h Indoor Unit Models
25.0 100.0 100.0
32.8 98.2 99.2
49.2 95.4 98.0
65.6 92.4 96.6
82.0 89.6 95.4
Capacity Coefficient Factors
Refrigerant Line Length Derates
For air-cooled systems, a capacity correction factor may have to be applied to account for the length of the system’s refrigerant pipe. Rate of
change in capacity due to increased piping lengths is shown in Table 92, Table 93, and Table 94.
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APPLICATION GUIDELINES | 169
Application Guidelines
MULTI
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MAX
MULTI
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