The Family Handyman – September 2019

(Joyce) #1




dding an A/C system sounds
like a job for pros only. And
usually it is. But two non-pros
installed this ductless “mini-split”
system in a garage in one day.
The installation was fast and easy
because of the special line set
(top right). It comes prefilled, or
“precharged,” with refrigerant and
includes connectors that don’t require
special skills or tools. Just mount the
two main units and connect the line
set to the condenser. Some mini-splits
include an easy-install line set, but
most don’t.
A mini-split system can be installed in
a home, a garage, a cabin or a shed.
Some offer heating as well as cooling,
and some include multiple evaporators
to serve multiple rooms. Depending on
features and size, most DIY mini-splits
cost from $700 to $2,000.

Choosing the system
Very few brick-and-mortar stores carry
DIY systems, so online shopping may
be your only option. Luckily there are
many online suppliers. The size of the
system is listed in BTUs (British ther-
mal units). The higher the number, the
greater the cooling capacity. To select
the right size mini-split, calculate the

heat loss of the room. Several websites
simplify these calculations. Don’t just
guess; an undersized system won’t
keep up, and an oversized system will
cycle on and off too frequently, short-
ening the condenser’s service life. We
installed a 12,000-BTU heating and
cooling system that costs about $1,100
at The other neces-
sary materials totaled about $275.

Providing power
Scan the photos on the following
pages and you’ll see that installation is
mostly basic DIY stuff: measuring, drill-
ing holes, driving screws ... Usually the
biggest challenge is running power to
the system. With a small system, you
may be able to draw power from a
nearby underloaded 20-amp circuit.
More likely, you’ll want to install a new
circuit dedicated to the mini-split. That
can be a small job or a major project
depending on how easy it is to run
cable from the main panel to the unit.
By cutting—and later patching—three
small holes in drywall, we were able to
run cable from the basement up
through the garage wall, through the
attic, then down and out the exterior
wall and into a disconnect box. (The
disconnect provides an easy, certain
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