MIL-PRF-24775A(SH)
4.5.2.6 Cooling performance. To determine the cooling performance of fan-coil units under various operating
conditions, cooling capacity tests shall be conducted at 4 airflow rates under the following conditions for fully wet
and fully dry air-side coil conditions with the fan running at high speed:
Unit model
Entering air temp.
Entering water temp.
Gal/Min
External static
(°F)
pressure (in. w.g.)
85 °F DB/71 °F WB
H-5
45
9.5
0, 0.1, 0.20, 0.25
95 °F DB/65 °F WB
H-5
50
9.5
0, 0.1, 0.2, 0.25
85 °F DB/71 °F WB
H-8
45
24.5
0.25, 0.5, 0.75, 1.0
95 °F DB/65 °F WB
H-8
50
24.5
0.25, 0.5, 0.75, 1.0
Cooling capacity tests shall be conducted in accordance with ASHRAE 33 and ARI 410 at 4 different face
velocities. The test unit shall be placed into the Code Tester Air Loop and Chilled Water Circuit and operated until
thermal equilibrium is attained. The duration of each test shall be 30 minutes after achieving equilibrium. Readings
shall be taken at the 0, 10, 20, and 30 minute marks. The arithmetic average of these readings shall be used for test
calculations. The test results shall be used to calculate the cooling capacity of all other sizes of fan-coil units in
accordance with ASHRAE 33 for provision of selection data. By using the unit cooling capacity data, airside
thermal resistance shall be calculated for each of the 4 airflow rates in accordance with ARI 410.
4.5.2.7 Isothermal water pressure drop. Water pressure drop through the chilled water cooling coil shall be
determined under isothermal operating conditions. Water flow tests shall be conducted at 4 different water flow
rates within the range per unit size specified below or up to a 12 lb/in2 drop, whichever occurs first.
Water flow rate range
Unit size
(gal/min)
1
0.5 to 6
2
1 to 8
3
2 to 12
4
3 to 16
5
4 to 20
6
5 to 28
7
6 to 32
8
10 to 50
4.5.2.8 Heater performance. The test unit shall be placed into the Code Tester Air Loop. The unit shall be
operated with motor at high speed, electric heater on, and an entering air temperature of 70 °F until thermal
equilibrium is attained. The test shall continue for 30 minutes after achieving equilibrium. Readings shall be taken
at the 0, 10, 20, and 30 minute marks. The arithmetic average of these readings shall be used for test calculations.
The following readings shall be taken during testing.
a.
Barometric pressure, inches of mercury (in Hg)
Entering air temperature (°F)
b.
(1) EDB
Leaving air temperature (°F)
c.
(1) leaving dry bulb (LDB)
(2) leaving wet bulb (LWB)
Ambient temperature (°F, AMB)
d.
e.
External static pressure (in. w.g.)
f.
Nozzle pressure drop (in. w.g.)
g.
Pressure after nozzle (in. w.g.)
16
For Parts Inquires submit RFQ to Parts Hangar, Inc.
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business