automatic controls arranged to properly heat, cool, and ventilate the room.
Automatic valves and controls shall be provided as specified in paragraph
CONTROLS. Sequence of control shall be any one of the standard ANSI cycles
specified in paragraph CONTROLS.
2.9.4.1
Enclosures
Fabricate enclosures from not lighter than 1.6 mm 16 gauge galvanized
steel, reinforced and braced, or all welded framework with panels to
provide equivalent strength. The casing shall be acoustically and
thermally insulated internally with not less than 13 mm 1/2 inch thick dual
density fibrous glass insulation. The exposed side shall be high density,
erosion-proof material suitable for use in air streams with velocities up
to 246 m/s 4500 fpm. Fasten the insulation with waterproof, fire-resistant
adhesive. Design front panel for easy removal by one person. [Discharge
grilles shall have adjustable grilles or grilles with adjustable vanes and]
[Discharge grilles] shall properly distribute air throughout the
conditioned space. Return grilles shall be removable where front panel
does not provide access to interior components. Plastic discharge or
return grilles are not acceptable. Furnish removable panels or access
doors for all piping and control compartments. Fan switch shall be key
operated or accessible through a locked access panel. Install gaskets at
the back and bottom of the unit for effective air seal, as required.
2.9.4.2
Electric Resistance Heating Elements
Electric resistance heating elements shall be of the sheathed, finned,
tubular type, or of the open resistance type designed for direct exposure
to the air stream. Heating element electrical characteristics shall be as
indicated. Where fan motor or control voltage is lower than required for
the electric-resistance heating element, provide a fused factory mounted
and wired transformer.
2.9.4.3
Fans
Fans shall be of the galvanized steel or aluminum, multiblade, centrifugal
type, dynamically and statically balanced. Equip fan housings with
resilient mounted, self-aligning permanently lubricated ball bearings,
sleeve bearings, or combination ball and sleeve bearings, capable of not
less than 2000 hours of operation on one oiling. Fans shall be
direct-connected.
2.9.4.4
Coils
Coils shall be circuited for a maximum water velocity of 2.4 m/s 8 fps
without excessive pressure drop and shall otherwise be as specified for hot
water coils in paragraph TERMINAL UNITS.
2.9.4.5
Drain Pans
Size and locate drain and drip pans to collect all condensed water dripping
from any item within the unit enclosure. Drain pans shall be constructed
of not lighter than 1.2 mm 18 gauge steel, galvanized after fabrication,
and thermally insulated to prevent condensation. Insulation shall be
coated with a fire-resistant waterproofing material. In lieu of the above,
drain pans may be constructed of die-formed 1.0 mm 20 gauge steel, formed
from a single sheet and galvanized after fabrication and insulated and
coated as for the 1.3 mm 18 gauge steel material, or of die-formed 1.3 mm
18 gauge type 304 stainless steel insulated as specified above. Pitch
SECTION 15895
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