Condensate Leak in the Attic in San Bruno

Condensate Leak in the Attic in San Bruno

An attic air handler's condensate has to travel further and through more turns than a garage or closet unit, so when the drain path fails, the water usually shows up as a ceiling stain before anyone notices a mechanical problem. The common causes are a clogged primary drain line, a cracked or corroded pan, a failed condensate pump, or a float safety switch that never cut power to stop the overflow. We trace the water to confirm it is condensate and not a roof or plumbing leak before opening anything up. The detail that matters in San Bruno is the sound-rated windows near the airport that seal the house tighter than it was designed for.

Local housing stock affects how an attic drain path was built and how it fails. San Bruno sits at the foot of San Bruno Mountain and directly under the SFO flight path, and a lot of homes here have upgraded windows for noise rather than for weather, which changes how the house actually breathes. Housing runs from mid-century tracts in Rollingwood and Portola Highlands to newer construction on the hillside. Sound-rated replacement windows are common near the airport corridor, and a house sealed tight against jet noise no longer gets the cross-ventilation it was designed around, which puts more of the comfort and air-quality job on the HVAC system.

In San Bruno, we confirm the source of the water before opening anything up, because an attic leak that turns out to be a roof or plumbing issue needs a different call entirely. Once we've confirmed it's condensate, the written estimate covers the drain, the pan, or the pump, whichever failed. The $99 diagnostic fee is credited toward the repair.

Common causes

Clogged primary condensate line. Algae and dust build up inside the line over the years until it backs up faster than it can drain, and the water finds the path of least resistance, usually straight through the attic-access ceiling.

Failed or undersized condensate pump. Where gravity cannot carry the line to a drain, a pump lifts the water out. A failed pump, or one that was undersized for the unit, leaves water with nowhere to go but over the pan.

Cracked or corroded primary pan. Pans crack and corrode with age, and the failure often only shows up under a full running cycle rather than sitting empty.

Float switch that never cut the system. The float switch exists specifically to shut the system down before an attic overflow becomes a ceiling stain. When it sticks or fails, that safety net is gone.

Improper pan slope from a settled install. A pan that has shifted out of level after the install settles no longer drains fully and leaves standing water that eventually finds a way out.

How we diagnose it

• Trace the water source to confirm it is condensate from the attic unit, not roof flashing or a plumbing line above the ceiling.
• Open the air-handler access panel and inspect the primary pan for rust-through, cracks, and standing water.
• Test the float switch by lifting the float to confirm it actually shuts the system off.
• Clear and flush the primary drain line, then watch the pan empty fully under a running cycle.
• On pump-assisted units, run the condensate pump under load and check the float and check valve.

$99 diagnostic, credited toward the repair. You get a written quote before any work begins.

Condensate Leak in the Attic in San Bruno: common questions

Nearby and related

Condensate Leak in the Attic near San Bruno: South San Francisco · Millbrae · Pacifica .

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