The window-unit legacy
Alabama cooled itself for two generations on window units, and its older housing remembers. Across Birmingham’s streetcar suburbs, Montgomery’s old grid and every county seat’s historic blocks, houses built long before central air are still crossing over: some fully, some halfway, some room by room as budgets allowed.
- 1 Thermostat. Where the season’s mileage actually accumulates.
- 2 Return and filter. Undersized in half the retrofits, and the reason the far room never cools.
- 3 Air handler and furnace. The part of the system Alabama barely uses, and almost never checks.
- 4 Coil and condensate drain. Liters of Gulf moisture a day, all leaving through one narrow line.
- 5 Attic ducts. Conditioned air, routed through the hottest space in the building.
- 6 Outdoor unit. Where a Gulf-coast August decides which capacitors see another summer.
What a retrofit inherits
A house that never planned for ductwork gives it up grudgingly: runs threaded through closets and chases, a return cut where the framing allowed rather than where the airflow wanted, equipment tucked into attics that were never meant to hold machinery. The recurring flaw is almost always the same, return air. A system starving through one undersized return grille runs loud, cools unevenly, and works harder than its size suggests, and no thermostat setting fixes a breathing problem.
The half-crossed houses carry both worlds: a central system serving the main rooms, window units still holding the additions and the sunroom, and an electrical panel juggling all of it. It works, the way inherited compromises work: until the day the household decides to finish the job, which is precisely the moment to finish it right.
Finishing the crossing well
The finishing move is design, not just equipment: a load calculation done on the real house, returns sized for the airflow the system needs, and an honest conversation about which spaces belong on the ducted system and which are better served by a mini-split: the modern answer for the sunroom, the garage apartment, the addition the ducts can’t gracefully reach.
Done that way, the old house cools better than it ever has, quietly and evenly, and the window units retire with honor. Done as an equipment swap into inherited compromises, the new system spends its career paying for decisions made in 1974. The difference between the two outcomes is one measuring visit, worth asking any bidder in an older neighborhood how much of their work is houses like this one.