Condensate Leak in the Attic in Palo Alto

Condensate Leak in the Attic in Palo Alto

Palo Alto's climate is among the mildest in the South Bay, with a strong marine influence and cooler summers, so cooling loads are modest. The homes that do carry attic air handlers, the newer infill across town and the revival-era stock in the older neighborhoods, still make condensate every time the AC runs. When the drain backs up, that water lands on a finished ceiling, and in an older home that ceiling is worth protecting.

Worth being clear about: this is a single-component problem far more often than a system failure. The coil makes water, a pan catches it, a line carries it out. A clogged line, a dead pump, a cracked pan, or a float switch that didn't do its job. Each one is a part-level repair. The emergency pan and float switch are the backstop before drywall gets wet, and on a lot of Palo Alto installs that backstop is either missing or has never been tested.

The Eichlers here are a different story. With post-and-beam ceilings and slab construction, many of them run ductless rather than a conventional attic air handler, so a true attic condensate leak is less common in an Eichler. Where we do see it is the conventional attic-handler homes, and that's where this guide applies. We find the actual cause rather than flushing the line and calling it done.

Common causes

Clogged primary condensate line. Biofilm and algae plug the drain at the trap or an elbow, water backs into the pan, and it overflows. We clear the line with a vacuum or nitrogen from the termination, confirm it flows, and treat it. If there's no cleanout, we add one so the line can be serviced without guesswork next time.

Float switch missing or failed. The safety float should shut the AC off before the pan spills. On many Palo Alto attic installs it was never wired in, or it's a low-cost switch that stuck. We test it by lifting the float and confirming shutdown. If it's absent, we install a proper float switch on the primary pan and the secondary drain.

Failed condensate pump. Attic units that can't gravity-drain use a small pump to lift water to a drain. A burned-out motor or a stuck check valve lets water collect until it overflows. We test the pump, replace it if it isn't lifting, and confirm it has a safety switch wired to cut the AC on a backup.

Cracked or rusted primary pan. Age cracks plastic pans and rusts steel ones. Once the pan leaks, a clear drain won't save the ceiling. We inspect the pan with a light and mirror, replace it when it's compromised, and give you a straight answer on whether the pan or the aging air handler is the right fix.

Improper pan slope. An air handler set off level holds water in the low corner of the pan and overflows there even with a clear drain. We check the unit with a level, re-set or shim it, and verify the pan slopes toward the drain fitting.

How we diagnose it

• Confirm the source is condensate from the attic air handler, not a roof leak landing on the same ceiling, which happens on flat and low-slope roofs.
• Inspect the primary pan, emergency pan, and both drain lines for standing water, cracks, rust, and a working trap.
• Lift-test the float switch and confirm the system shuts off; flag it if it's missing.
• Clear and flow-test the primary line, then test the pump and its safety switch where gravity drainage isn't possible.
• Level the unit and verify pan slope before we sign off.

$75 diagnostic, credited toward any repair over $200. You get a written quote before any work begins.

Condensate Leak in the Attic in Palo Alto: common questions

Nearby and related

Condensate Leak in the Attic near Palo Alto: Menlo Park · Los Altos · Mountain View .

This is usually a ac repair in Palo Alto job. See our ac repair overview or the Palo Alto service area.