High-Efficiency Furnace Condensate: Why It's Acidic and How to Neutralize It

Your 95% furnace makes water when it runs — and that water is acidic. Here’s the simple chemistry and the simple fix.

The chemistry, briefly

A condensing furnace extracts so much heat that exhaust water vapor condenses to liquid. Combustion byproducts make that condensate mildly acidic, typically pH 3–5 — acidic enough to corrode metal drains and concrete over time.

Why code often requires neutralizing

Many jurisdictions require condensate to be neutralized before it enters the drain to protect plumbing and municipal systems. Even where it isn’t required, it protects your own pipes.

How a neutralizer works

Condensate flows through media that raises the pH toward neutral before discharge. The Axiom NeutraPal is wall-mounted, has a manual-reset float that flags a restriction, and a bypass to prevent backflow into the appliance.

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