OO-A-373D
appropriate type of heating coil or heat exchanger can be specified. Steam and hot water heating on outdoor rooftop-mounted units are usually available in sizes 20 to 75 tons. Larger models and small models are usually available in gas or electric heat only. Indoor vertical self-contained units are usually available in 3 to 80 tons cooling capacity and have provisions for electric, steam, or
hot water heating but not gas heating. For steam and hot water coils, the following information should be supplied:
a. Velocity of air across coil face, feet per minute (ft/min) (metre per second (m/s) standard air.
b. Entering the dry-bulb temperature, F ( C).
c. Water velocity range, ft/min (m/s) - hot water coil.
d. Entering water temperature, F ( C), - hot water coil. e. Steam pressure at coil, inlet, psi (kPa) - steam coil.
f. Maximum superheat in steam at coil inlet F ( C), - steam coil.
6.1.4 Style A. Style A units can be specified where the conditioner can be discharged directly into the conditioned space. To accomplish this, the unit must be located either within the conditioned space, adjacent to the space, or on the roof over the space.
6.1.5 Style B. Style B units can be specified where duct work is necessary to supply the cooled air conditioned space. The unit is usually located outside the conditioned space and duct work is required to deliver the cooled air to the conditioned space, or where the unit is located in a conditioned space and connected to other spaces by duct work.
6.1.6 Application rating. Many applications of unitary units require ratings under conditions other than standard rating conditions of ARI 360 (see 3.5.1.5 and 6.9). The following
information of table I should be supplied by the acquisition authority to the contractor as indicated by the "x" in the applicable blocks.
TABLE I. Operating conditions for applications rating and performance tests.
Test |
Indoor coil air entering DB WB |
Condenser cooling means |
Minimum External Resistance Inches (mm) of water |
|
Water In Out |
Air to Condenser DB |
|||
F F ( C) ( C) |
F F ( C) ( C) |
F ( C) |
||
Maximum operating conditions Low temperature operation Condensate disposal |
x x x x |
x x - x |
x x |
x (x) |
6.1.7 Corrosion protection. Indoor unit components made of ferrous metals located in marine atmosphere should withstand 125 hours of 100 percent relative humidity per ASTM D 2247.
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