Specification Guide

Determine the Corrected Capacity
The corrected cooling / heating capacity is different from the rated cooling / heating capacity. The corrected capacity includes changes in
unit performance after considering design temperatures, available capacity that can be allocated from the outdoor unit, pressure drop due
to refrigerant line length, defrost operation in heating mode, and (if applicable) altitude. Depending on the location of the building, additional
capacity correction factors will need to be applied.
Using the Outdoor Unit Cooling and Heating Capacity Tables
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To evaluate the total outdoor unit capacity at design conditions perform a selection using LATS Multi F software (preferred method) or refer-
ence the Performance Data Capacity Tables. All design temperatures are not explicitly shown in the charts, therefore, interpolation will be
necessary to calculate the capacity for specific design conditions. Based on the premise that capacity follows a linear curve, the following
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(y - y1) / (y2 - y1) = (x - x1) / (x2 - x1)
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y = Missing Capacity (Capacity at the Design Temperature).
1
y1 = Capacity at Lower Temperature (Smaller value of the two nearest published TC datapoints).
y2 = Capacity at Higher Temperature (Higher value of the two nearest published TC datapoints).
x = Design Temperature (Temperature not shown in published capacity tables).
2
x1 = (Smaller value of the two nearest published temperature datapoints).
x2 = (Larger value of the two nearest published temperature datapoints).
1
Median between two published Total Capacity [TC] Btu/h datapoints in the capacity table.
2
Median between two nearest published temperature datapoints.
EQUIPMENT SELECTION PROCEDURE
Using the Indoor Unit Cooling and Heating Capacity Tables
The datapoints shown in the indoor unit cooling and heating capacity charts are based on (and convey) an indoor unit operating with maxi-
mum possible refrigerant flow from the outdoor unit and before any derates are applied. In other words, the capacities displayed reflect what
the indoor unit would produce if it was the only indoor unit that required capacity, and the outdoor unit did not have to allocate any capacity to
another indoor unit.
System operation with a combination of indoor units is not conveyed in these charts, however, the information can be used to calculate
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Qidu(combi) = Qodu(rated) x Qidu(rated)
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• The formula can be used to find individual indoor unit capacity for Multi F MAX / Multi F MAX with LGRED systems.
• A more accurate method to determine expected capacity would be to apply the outdoor unit’s corrected capacity instead of rated capacity.
Qidu(combi) = Individual Indoor Unit Combination Capacity.
Qodu(rated) = Outdoor Unit Rated Capacity.
Qidu(rated) = Individual Indoor Unit Rated Capacity.
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7DEOH Multi F / Multi F MAX with LGRED Rated Outdoor Unit Capacity.
Outdoor Units
LMU180HHV LMU240HHV LMU300HHV LMU360HHV LMU420HHV
Rated Capacity
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Cooling 18,000 24,000 28,400 36,000 42,000
Heating 22,000 26,000 28,600 41,000 45,000
Connectable
Indoor
Units
Minimum No. of Connectable IDUs 2 2 2 2 2
Maximum No. of Connectable IDUs 2 3 4 5 6
Maximum Capacity Index 24,000 33,000 40,000 48,000 56,000
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188 | APPLICATION GUIDELINES
Multi F and Multi F MAX Indoor Unit Engineering Manual
MULTI
F
MAX
MULTI
F