The air handler in the attic
On a house built on a slab there is no basement and no crawl space to hide machinery in, so the air handler goes where the room is: the attic, directly above your ceiling. It works fine there for years. When it stops working fine, the failure has gravity on its side.
- 1 Thermostat — The season’s odometer — a hundred cooling days pass through it.
- 2 Return and filter — The lungs, and the first thing a retrofit house sized too small.
- 3 Air handler and furnace — Up in the attic, asleep nine months, asked for everything in December.
- 4 Coil and condensate drain — Litres of river-valley moisture a day, leaving through one narrow line above your ceiling.
- 5 Attic ducts — The coldest air in the house, commuting through the hottest room on the property.
- 6 Outdoor unit — Full sun, full load — where August culls capacitors by the thousand.
A machine that makes water, above drywall
Cooling produces condensate — in Memphis humidity, a great deal of it, hour after hour all summer. That water is supposed to leave through a small drain line. When algae and dust narrow the line, as they reliably do in this climate, the water backs up into the drain pan under the unit. What happens next is decided by two inexpensive parts most homeowners have never heard of.
The float switch is a small sensor that shuts the system down when the pan fills. Without it, the pan overflows onto the ceiling below and the repair stops being an HVAC number and becomes a drywall-and-paint number. The secondary pan — a larger tray under the whole unit, with its own drain to a visible spot outside — is the second line: when you see water dripping from a soffit in August, that pan is doing its job and telling you the primary drain has failed. Both parts belong on any attic installation, and both are worth confirming by name on a quote.
Heat, access and the service reality
Attic equipment lives hot. Electronics, capacitors and blower motors all age faster in a space that spends a hundred afternoons well above outdoor temperature, and the same heat makes every service visit slower and less pleasant — which quietly affects how thoroughly the work gets done. Decent attic installations account for it: a proper walkway to the unit, a light, and enough clearance to actually open the panels.
It also shapes the maintenance calendar. The drain deserves a flush every spring before the humidity arrives, the pan and float switch deserve a look at the same visit, and if the attic has no walkway, that is worth fixing while a technician is up there anyway. None of it is expensive. All of it is cheaper than the ceiling.