coils. The research should include a survey of
existing similar equipment. If needed, rewrite the
specifications based on the conclusions of the
research. Consideration should be given to the
following combinations based on past experience of
these materials in dealing with the local conditions.
1.
Copper tube and aluminum fins, coated;
2.
Copper tube and copper fins, coated;
3.
Aluminum tube and aluminum fins, coated;
4.
Aluminum tube and aluminum fins, uncoated;
5.
Copper tube and copper fins, uncoated; and
6. Copper tube and aluminum fins, uncoated.
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Extended-surface fin and tube type with seamless copper or aluminum tubes
with copper or aluminum fins securely bonded to the tubes. On coils with
all-aluminum construction, provide tubes of aluminum alloy 1100, 1200, or
3102; provide fins of aluminum alloy 7072; and provide tube sheets of
aluminum alloy 7072 or 5052. [Provide a coating on [outdoor air] [and]
[indoor air] coils as specified in the paragraph entitled "Coatings for
Finned Tube Coils." Coils to be coated shall be part of manufacturer's
standard product for capacities and ratings indicated and specified.
Provide plate type fins.]
2.4.3
Supplemental Electric Heaters
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NOTE: Determine if supplemental electric heaters
are required.
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Provide electrical resistance heaters [integral with the unit] [for remote
installation in ductwork]. Heaters shall have a total capacity as
indicated. Provide internal fusing for heaters.
2.4.4
Compressors
For compressors above 70 kW 20 tons, compressor speed shall not exceed 3450
rpm. For equipment over 35 kW 10 tons, provide automatic capacity
reduction of at least 50 percent of rated capacity. Capacity reduction may
be accomplished by cylinder unloading, use of multiple, but not more than
four compressors, or a combination of the two methods. Units with cylinder
unloading shall start with capacity reduction devices in the unloaded
position. Units with multiple compressors shall have a means to sequence
starting of compressors. Provide compressors with devices to prevent short
cycling when shutdown by safety controls. Provide reciprocating
compressors with crankcase heaters, and vibration isolators.
2.4.5
Mounting Provisions
Provide units that permit mounting as indicated. [Provide suitable lifting
attachment plates to enable equipment to be lifted to normal position.]
SECTION 15730N
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