MIL-PRF-23798D(SH)
TABLE I. Capacity rating (nominal).
Fan-coil
Cooling coil air and water flow
External static pressure,
Fan
type III units only
assembly
for rated capacity
Capacity
Air
Water
Motor
External static pressure
Sizes
(Btu/h)
(SCFM)
(gal/min)
horsepower (max)
(in w.g.)
21
31,300
620
9
1½
2
22
51,200
1035
16
3
2
23
77,600
1540
23
5
2
24
99,800
2065
31
5
2
25
151,300
3080
44
7½
2
3.11.8 Type II, fan-coil assembly. The type II fan-coil assembly shall be a three-section unit consisting of a
cooling coil section, which shall be the base of the unit, a fan-motor section, which shall be on top of the cooling coil
section, and the air distribution plenum section on top. Each section shall be not greater than 25 inches in height,
and when assembled together, the overall height of the unit shall be not greater than 75 inches. The overall width
and depth of each assembled unit shall be not greater than the dimensions shown on Figure 1.
3.11.8.1 Cabinet. The cabinet enclosure of each section shall be constructed of a material equivalent in strength
to 0.074-inch steel. The cabinet frame shall be rigid and of a strength to support and maintain alignment of the
assembled parts. The cooling coil section shall be fitted with at least four reinforced pads, one at each corner of the
section, for securing the assembled fan-coil assembly by bolting to a structural foundation.
3.11.8.2 Cooling coil section. The cooling coil section shall consist of a cooling coil and a condensate pan with
a drain of 1-inch nominal pipe size (nps) on each end. Condensate pan shall be constructed to prevent slosh over
when unit is tilted 15 degrees. Connection to the condensate drains shall be possible without the removal of an
access panel. The cooling coil shall be serviceable through a front access panel. Provision shall be made to permit
access to and removal of the cooling coil without disassembly of the fan-coil assembly. Provision shall be made to
permit making a left-hand or right-hand assembly of the cooling coil by the installing activity after delivery.
Removable panels, if used, shall use capture type fasteners and shall be airtight when installed. Unless otherwise
specified (see 6.2), the fan-coil assembly shall be delivered with the chilled water supply and return connections of
the cooling coil to the right when facing the front of the assembled fan-coil. A tapped hole shall be provided for -
inch bolt on bottom right back of unit for attachment of grounding strap.
3.11.8.3 Fan-motor section. The fan-motor section shall consist of a centrifugal fan, fan drive, electric motor,
fan and motor base with resilient mounts, and air filters. Provision shall be made to permit access to and removal of
the fan. Removable panels, if used, shall use captive type fasteners, and shall be airtight when installed. Provisions
shall be made to permit access to the air filters, fan drive and the fan-motor, service and adjust the fan belts and
pulley, and remove the fan pulley and the fan motor without disassembly of the fan-coil assembly.
3.11.8.4 Air distribution plenum section. The air distribution plenum section shall include a single air inlet
located on top of the cabinet. Provisions shall be made in the air distribution plenum for one air outlet on the top and
one on each end. The inside dimensions of the air inlet and each of the air outlets shall be as shown on Figure 1.
Three options are available in the air distribution plenum section: the air inlets and outlets shall have smooth flat
surfaces for attachment of flanged duct connections, each air outlet shall be supplied with a grille, or a coverplate
shall be supplied that harmonizes with the cabinet enclosure. The grille shall be constructed to permit adjustable
directional airflow in both horizontal and vertical planes. Unless otherwise specified (see 6.2), the fan-coil assembly
shall be supplied with coverplates. The coverplates shall be gasketed.
3.11.8.5 Static air pressure tap. Fan-coil assemblies shall be provided with a static air pressure tap on the
downstream side of the filters for permanent mounting of a differential pressure gauge or for checking static air
pressure with a portable differential pressure gauge. The tap shall consist of a gasketed, brass or corrosion-resistant
steel, ¼-inch tube, straight bulkhead connection with sealing cap and protective cover suitable for permanent
mounting to side of cabinet.
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