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(PTHPs), DX unit ventilators, room air conditioners, split DX fan coils, ductless split units and other
similar products. The packaged version of the equipment contains a supply fan, air-cooled DX cooling
apparatus and heating apparatus in one packaged unit. The split version of the equipment contains a
supply fan, DX cooling coil and heating apparatus in an indoor unit plus an outdoor condensing unit.
Heating options include electric resistance, combustion, heat pump, hot water and steam. Modeling
procedures are described below.
1. Air Systems. Define one air system for the entire collection of DX fan coil units. HAP will model
each zone in the system as containing one fan coil unit. Loads for each zone and the performance of
each zone's fan coil unit will be performed separately. Loads and energy use are then summed to
obtain system totals which are displayed on the simulation reports. Modeling tips:
" Specify the Equipment Class as "Terminal Units"
" Specify the System Type as "Packaged DX Fan Coil" or "Split DX Fan Coil" and enter system
data.
" Define performance characteristics of the DX cooling equipment using the Equipment Tab on the
Air System form. Be sure to define performance data for all zone fan coils.
" If heat pump or combustion heating is used, define performance characteristics of the equipment
using the Equipment Tab on the Air System form. Again, be sure to define performance for all
zones.
" If electric heat is used, no additional heating equipment inputs are required.
" If the number of fan coil units exceeds the number of zones permitted in a system, then an
additional system will be required to accommodate the extra fan coils.
2. Plants. If heat pump, combustion or electric heat is used then no plant equipment is required. If hot
water or steam heating is used, a hot water or steam plant must be defined and must link to the fan
coil air system. If the heating plant serves multiple air systems, a single plant can be defined and
linked to all air systems containing hot water or steam coils.
3. Building. If electric resistance, heat pump or combustion heating is used, link the air system directly
to the building. If hot water or steam heating is used, link both the system and the plant to the
building.
Note: Fan coil systems are good candidates for the reduction techniques discussed in section 6.2.
However, if you use these techniques to reduce input and calculation time, planning is required to
account for the correct number of fan coil units in the building.
Example: A hotel is being studied which has 75 identical fan coil zones on the south face of the building,
62 identical fan coil zones on the north face of the building and 48 fan coil zones which are unique. In
this situation it may be best to define three air systems. System #1 would contain 48 zones holding the
48 fan coil units that are unique. System #2 would contain only one zone representing the typical south-
facing zone. System #3 would contain only one zone representing the typical north-facing zone. When
linking systems to the building a system multiplier of 1 would be used for system #1, a multiplier of 75
would be used for system #2 and a multiplier of 62 would be used for system #3. This is necessary
because multipliers are applied at the system level when linking systems to plants and buildings.
HAP Quick Reference Guide 6-7
Chapter 6 Design Applications
An alternate approach is to lump identical fan coils together rather than defining a single typical unit for
each. This means that the 75 south facing fan coil zones would be combined, using a space multiplier of
75. The cooling and heating equipment inputs would define full load capacity and input power values
that are the sum of the 75 fan coil capacities and input powers rather than the actual capacity and power
for one representative unit. This approach would allow the typical north and typical south zones to be
included in System #1 with the 48 unique zones while still correctly accounting for the total loads and
energy use of these fan coil units.
6.9 SIMULATING HYDRONIC FAN COIL UNITS
This section explains how to model hydronic fan coil units in energy simulations. This equipment
contains a supply fan, a chilled water coil and a heating coil in one packaged indoor unit. Heating
options include hot water, steam and electric resistance. Modeling procedures are described below.
1. Air Systems. Define one air system for the entire collection of hydronic fan coils. HAP will model
each zone in the system as containing one fan coil unit. Loads for each zone and the performance of
each zone's fan coil unit will be performed separately. Loads and energy use are then summed to
obtain system totals which are displayed on the simulation reports. Modeling tips:
" Specify the Equipment Class as "Terminal Units"
" Specify the System Type as "2-Pipe Fan Coil" or "4-Pipe Fan Coil" and enter system data.
" If electric heat is used, no additional heating equipment inputs are required.
" If the number of fan coil units exceeds the number of zones permitted in a system, then an
additional system will be required to accommodate the extra fan coils.
2. Plants. Define a chilled water plant to provide chilled water to the fan coil units. Plant options
include chiller plants and remote chilled water (district cooling).
If hot water or steam heating is used, define a hot water or steam plant to provide heating to the fan
coil units. Plant options include boiler plants and remote (district) heating. If electric resistance
heating is used then no heating plant is required; electric heat energy use will be included in the air
system calculations.
3. Building. Link the hydronic fan coil system as well as the cooling plant and the heating plant (if
used) to the building.
Note: Fan coil systems are good candidates for the reduction techniques discussed in section 6.2. Please
refer to the note at the end of section 6.8 for a discussion of special considerations when reducing the
number of fan coil units modeled.
6.10 SIMULATING WATER SOURCE HEAT PUMP SYSTEMS
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