Product data
SELECTION PROCEDURE (With Example)
Rev “A”
09/19/01
I Determine the type of fan coil, which best suits the application (refer to Systems Index table in the
Expanded Rating Section #13).
Duct-free split systems have many types of fan coils to choose from with overlapping capacities. Select the system type, which
best meets the job conditions. This example will use a 2-ton ceiling-suspended fan coil (assume wall space is not available for a
wall-mounted unit).
II Determine cooling and heating load requirements at design conditions.
Required Load Conditions:
Required Cooling Capacity (TCG) 24,500 Btuh
Sensible Heat Capacity (SHG) 16,800 Btuh
Temperature Air Entering Outdoor Unit 95F
Temperature Air Entering Indoor Unit (EAT) 82Fdb/68 F wb
Required Heating Capacity 8,500 Btuh
Indoor Heating Design Conditions 68F
Outdoor Heating Design Conditions 0°F
db — dry bulb
wb — wet bulb
III Select system that satisfies load requirements.
Enter the Systems Index table (Section 13) ceiling-suspended system for 24,000 Btuh, and select the system that best
approximates cooling and heating requirements. System index no. 32C & 32H with a nominal net capacity of 24,000 Btuh
cooling and 22,600 Btuh heating is the system selected. The system consists of a 38QR024C outdoor unit matched with a
40QAE024 indoor unit.
IV Determine if system selected satisfies cooling requirements.
Enter Expanded Rating table 32C, at high speed (550 cfm) and 95 F outdoor entering air temperature (air entering condenser).
By interpolation, at 68 F EAT, the system gross capacity is 24,900 Btuh cooling [(26,500 – 24,500) x (1/5) + 24,500], and 15,740
Btuh SHG (gross sensible capacity). Adjust the SHG in accordance with Note 2 of the Gross Cooling Capacities table, using the
correction factor for an 82 F edb (air entering dry bulb), and a 0.03 BF (bypass factor). The result is an adjusted SHG of 16,877
Btuh. The total gross cooling capacity of 24,900 Btuh and the sensible heat capacity of 16,877 Btuh satisfy stipulated cooling
load requirements.
V Determine if system selected satisfies heating requirements.
Enter Instantaneous and Integrated Heating Ratings table #32H at 0° F outdoor db. By interpolation, the system capacity is
between 65 and 70 F for integrated heating [-(7320 - 7710) x (2/5) + 7320 = 7476]. This is the value that reflects the net room
effects after defrost energy. This value is short of the required heating capacity, however, the 40QAE units have a standard
electric heater which will work in conjunction with heat pump heating (booster heat mode). The 40QAE024 units have a 2 kw
heater that will add 6824 Btuh (2 × 3412) to the room for a total heating capability of 14,300 Btuh at design heating conditions.
This will satisfy the required heating load.
VI Determine net cooling capacity and system energy efficiency ratio
.
Determine net cooling capacity (refer to Cooling Capacity table for System 32C). Net total cooling capacity must be interpolated
as follows: (26,000 - 24,000) x (1/5) + 26,000 = 26,400 Btuh. To determine the energy efficiency ratio (EER), system kW must
be interpolated from the Cooling Capacity table for System 32C in the same manner: (2.47 - 2.40) x (1/5) + 2.40 = 2.41 kw. Then
calculate EER: Net Cooling Capacity / (kw x 1000) = EER: 26,400 / (2.41x1000) = 10.95 EER
NOTE:
The SEER (Seasonal Energy Efficiency Ratio) CANNOT be calculated for this system. SEER can only be found as a
direct result of testing at specified ARI conditions. See ARI Capacities Section.
VII Determine COP (coefficient of performance) at the design point.
To calculate the COP at the design point, interpolate capacity as in Step V to arrive at a capacity of 7476. Interpolate the kw
between 1.63 and 1.62 to be 1.625. COP =(7476 / (1.625 × 3.412)) / 1000 = 1.348
NOTE:
The HSPF (heating seasonal performance factor) CANNOT be calculated for this system. HSPF can only be found as a
direct result of testing at specified ARI conditions. See ARI Capacities Section.
VIII Determine the recommended liquid and vapor line sizes.
Refer to Refrigerant Lines section.
NOTE:
With long-line applications, it may be necessary to adjust cooling capacity. See Refrigerant Lines & Long Line
Application section for more details.
Note: A fully automated selection program can be found in the Sales Pro Suite & Quote
Builder Module