YOUR AC DRAIN LINE
MAY BE FEEDING
TERMITES

Your AC removes humidity from the air as part of the cooling process. Even in Arizona's dry climate, monsoon season (June–September) brings significant humidity — sometimes 50–70% relative humidity during storms. When warm, humid air passes over your AC's cold evaporator coil, moisture condenses on the coil and drips into the condensate drain pan, then flows out through the drain line. A 3-ton AC can produce 5–20 gallons of water per day during humid conditions. That water has to go somewhere — and where it goes matters enormously for your home's structural health.

Termites need three things to thrive: cellulose (wood), warmth, and moisture. In Arizona's desert climate, moisture is the limiting factor — which is why your AC drain line is a termite magnet. Most Phoenix-area home builders route the AC condensate drain to exit just 2–3 inches from the home's foundation. This creates a constant moisture source directly adjacent to the wood framing and sill plates of your home. Subterranean termites — the most destructive species in Arizona — build mud tubes from moist soil to wood, and a drain line 2 inches from your foundation gives them exactly the moisture they need to establish a colony. Bradford recommends extending your AC drain line at least 2 feet beyond the foundation perimeter to eliminate this moisture source.

Bradford recommends a minimum of 2 feet beyond the home's foundation perimeter. Most Phoenix-area builders install the drain termination 2–3 inches from the foundation — just enough to clear the stucco. This is code-compliant but creates a chronic moisture problem at the most vulnerable part of your home's structure. Bradford can extend the drain during any AC service visit.

When the primary condensate drain clogs — usually with algae, mold, or debris — water backs up in the drain pan. If the overflow pan (secondary pan) is properly installed and connected to a secondary drain, the water exits safely. However, many Phoenix-area homes have improperly installed overflow pans with no secondary drain connection, or the secondary drain terminates in a wall cavity. When both the primary drain and overflow pan fail, water overflows onto the ceiling drywall, causing water stains, mold growth, and in severe cases, ceiling collapse. Bradford clears clogged drains and inspects overflow pan installation during every AC service visit.

Signs of a properly installed overflow pan: (1) there is a secondary drain line (usually a white PVC pipe) that exits through an exterior wall or soffit — separate from the primary drain, (2) the overflow pan sits directly under the air handler with no gaps, (3) the pan has a float switch that shuts off the AC if water reaches a certain level. Signs of an improperly installed overflow pan: no visible secondary drain line, the pan is cracked or corroded, or there is no float switch. Bradford inspects overflow pan installation during every AC service visit and can add a float switch ($248 standard, $319 for attic-mounted air handlers) to prevent ceiling damage.

Bradford recommends cleaning the condensate drain line once per year as part of the annual AC tune-up. In Surprise and Peoria, algae growth in drain lines is accelerated by the combination of warm temperatures and monsoon-season humidity. Signs your drain needs cleaning: water dripping from the air handler, musty smell from vents, AC shutting off unexpectedly (if a float switch is installed), or visible water stains on the ceiling below the air handler. Bradford's $59 AC tune-up includes a condensate drain flush.

A float switch is a safety device installed in the overflow pan or drain line that shuts off the AC when water reaches a dangerous level. When the primary drain clogs and water begins to fill the overflow pan, the float switch triggers before water can overflow onto your ceiling. Float switches cost $248 (or $319 for attic-mounted air handlers) and can prevent thousands of dollars in ceiling and drywall damage. Bradford recommends float switches for all Surprise and Peoria homes with air handlers located in attics or above finished living spaces.