Cooling Info From Warmair.net
Cooling Coils
Evaporator coils come in a variety of shapes and sizes, depending on the
type of installation, the amount of cooling capacity needed, and
the manufacturer. It is the source of cooling as air passes through
the furnace or air handler. They are constructed of aluminum-finned
copper tubing. The copper tubing runs perpendicular to the aluminum
fins, making U-turns back and forth until the desired coil size
is achieved. Added cooling capacity without an increase in length
and width is accomplished by adding more rows of copper tubing.
Slant coils and horizontal coils have a slab appearance, similar to the radiator
in an automobile. They can be installed in ductwork running horizontally
or in an air handler. An A-coil is shaped like a capital A without
the crossbar. It can be installed on top of a fuel burning furnace
heat exchanger or in an air handler. The newest design is the
multi-flex coil which is a series of A-coils linked together at
the base. The multi-flex coil can be installed in any position
when encased in a special cabinet. All evaporator coils must have
a drain pan to collect the water that condenses as the air flowing
across the coil cools. The water can drain away by gravity or
be pumped away.
The cooling effect that takes place inside the coil requires a pressure drop
in the refrigerant. This drop can be accomplished in a number
of ways: capillary tube, piston or orifice, or thermostatic expansion
valve.
A capillary tube is a thin copper tube of predetermined length into which
the compressed liquid refrigerant is pumped. The length of the
tubing causes the pressure drop and subsequent cooling effect of the refrigerant.
A piston or orifice blocks the flow of refrigerant and forces it through
a tiny hole, creating the needed pressure drop.
A thermostatic expansion valve meters the flow of refrigerant to meet the cooling
demand of the coil. It determines this demand by way of a sensing
bulb attached to the outlet tube on the coil. Because it can meter
the flow to meet demand, the expansion valve can keep the coil
at optimum cooling potential.
Copyright © 1999 Warmair.com, Inc.
Back to Main Page
 Email this page to a friend
|
