We're in an attic in Phoenix,
directly over the closet that holds
the air handler. With a flashlight
and smoke pencil, which makes the
air stream visible, we watch hot attic
air being sucked into return duct fittings
and down the interior partition
walls into the air-handler's platform
plenum below. Later, while inspecting
the crawlspace, we see chilled air
leaking out of supply branch lines
where they exit the trunk line. With
attic temperatures averaging more
than 20°F higher than outdoor temperatures
it's no wonder the occupants
are disappointed with their air
conditioner's performance. After all,
it's trying to cool 120°F attic air
while losing cooled air to the
crawlspace.
The preceding scenario is unfortunately
the rule rather than the
exception. And