Cooling without Ductwork
A ductless mini-split air conditioner works the same way central air
conditioning does with one big difference—there’s no ductwork.
Both the central system and the mini-split can be classifi ed as
split systems because they consist of an outdoor condensing
unit and an indoor air handler. With a central A/C system, the
indoor components include a cooling coil and an air handler (the
furnace’s blower or a separate air handler) that circulates the
conditioned air throughout the structure by way of the ductwork.
The mini-split indoor unit functions as both the indoor coil and
the air handler, delivering conditioned air directly into a single
room without sending it through any ductwork.
Heat Pump Models
A heat pump mini-split operates in basically the same manner,
but adds heating capability. In the summer it transfers heat
from inside the home to the outdoors. A reversing valve makes
it possible for the unit to reverse this procedure during cold
weather, absorbing heat from the outdoors and transferring it
indoors (yes, there is warm air outside, even when it’s below
freezing).
Heat Gain/Loss
One of the advantages this “ductless” operation provides is
effi ciency. In a central system, the cooler air absorbs heat as
it travels through the ductwork. The longer the duct run, the
greater the temperature gain. In winter, heat can also be lost as
the conditioned air travels through the ducts.
Don’t forget that it takes air pressure to move the conditioned air
through the ducting system and that involves some noise from
the fan and the actual movement of air. A mini-split system,
however, is ultra-quiet because it doesn’t have to push the air
through many feet of ductwork.
Indoor Air Handler
How does a
mini-split
work?
This diagram shows a typical
single zone installation:
n
The condensing unit is
installed outdoors while
the air handler is mounted
inside on an exterior wall.
A hole approximately 3” in
diameter is drilled through
the wall. The lines that carry
refrigerant from the air
handler to the condensing
unit and back run through
this hole.
n
An electric line runs between
the two components: power
is supplied by the outdoor
unit so there are no cords and
plugs visible on the interior. A
bracket mounted to the wall
supports the air handler, but
is hidden by air handler.
n
A drain line runs from the
air handler to the outside to
carry condensate away.
Outdoor Condenser
Ou
td
oor
Co
nd
ense
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