Bryant PREFERRED 581J - Manual (Page 24)

24
APPLICATION DATA (cont.)
Sizing a rooftop
Bigger isn’t necessarily better. While an air conditioner
needs to have enough capacity to meet the design loads, it
doesn’t need excess capacity. In fact, excess capacity
typically results in very poor part load performance and
humidity control.
Using higher design temperatures than ASHRAE
recommends for your location, adding “safety factors” to
the calculated load, are all signs of oversizing air
conditioners. Oversizing the air conditioner leads to poor
humidity control, reduced efficiency, higher utility bills,
larger indoor temperature swings, excessive noise, and
increased wear and tear on the air conditioner.
Rather than oversizing an air conditioner, engineers
should “right--size” or even slightly undersize air
conditioners. Correctly sizing an air conditioner controls
humidity better; promotes efficiency; reduces utility bills;
extends equipment life, and maintains even, comfortable
temperatures. Please contact your local Bryant
representative for assistance.
Low ambient applications
The optional Bryant economizer can adequately cool your
space by bringing in fresh, cool outside air. In fact, when
so equipped, accessory low--ambient kit may not be
necessary. In low ambient conditions, unless the outdoor
air is excessively humid or contaminated,
economizer--based “free cooling” is the preferred less
costly and energy conscious method.
In low ambient applications where outside air might not
be desired (such as contaminated or excessively humid
outdoor environments), your Bryant rooftop can operate to
ambient temperatures down to --20_F (--29_C) using the
recommended accessory Motormaster low ambient
controller.
581J