will be deleted for noncritical areas. Sound values
will be selected by the designer based on a study of
the design goal. The ASHRAE Handbook, Fundamentals,
shows the range of sound pressure values for speech
communications as being 50 dB for fair, 44 dB for
very good, and 38 dB for perfect speech
intelligibility.
**************************************************************************
Heaters shall be as specified below, and shall have a heating capacity not
in excess of 125 percent of the capacity indicated. [Noise level of each
unit heater for areas noted shall not exceed the criteria indicated.]
2.8.1
Propeller Fan Heaters
Heaters shall be designed for suspension and arranged for [horizontal]
[vertical] discharge of air as indicated. Casings shall be not less than
0.912 mm (20 gauge) 20 gauge black steel and finished with lacquer or
enamel. Suitable [stationary] [rotating air] deflectors shall be provided
to assure proper air and heat penetration capacity at floor level based on
established design temperature. Suspension from heating pipes will not be
permitted. [Fans for vertical discharge type heaters shall operate at
speeds not in excess of 1,200 rpm, except that units with 84.4 MJ (80,000
Btu) 80,000 Btu output capacity or less may operate at speeds up to 1,800
rpm.] [Horizontal discharge type unit heaters shall have discharge or face
velocities not in excess of the following]:
[Unit Capacity, Liters per Second
Face Velocity, Meters per Second
Up to 472 (1000)
4.06 (800)
473 (1001)
4.57 (900)
1417 (3001)
5.08 (1,000)]
[Unit Capacity,
cfm
Face Velocity, fpm
Up to 1,000
800
1,001 to 3,000
900
3,001 and over
1,000]
2.8.2
Centrifugal Fan Heaters
Heaters shall be arranged for floor or ceiling mounting as indicated.
Heating elements and fans shall be housed in steel cabinets of
sectionalized steel plates or reinforced with angle-iron frames. Cabinets
shall be constructed of not lighter than 1.27 mm (18 gauge) 18 gauge black
steel. Each unit heater shall be provided with a means of diffusing and
distributing the air. Fans shall be mounted on a common shaft, with one
fan to each air outlet. Fan shaft shall be equipped with self-aligning
ball, roller, or sleeve bearings and accessible means of lubrication. Fan
shaft may be either directly connected to the driving motor or indirectly
connected by adjustable V-belt drive rated at 150 percent of motor
capacity. All fans in any one unit heater shall be the same size.
SECTION 15569A
Page 38
Previous Page
