HVAC Auxiliary Lines

The HVAC units of a home are one of the most expensive items to repair or replace. But how do we know if it even needs to be looked at by a qualified licensed HVAC service technician? There are several obvious signs, or indications, we can readily see that can give us a hint or two.

In this article I’m going to tell you about one of the most obvious, that is the auxiliary, or secondary, drain line. Although not all HVAC units have an actual auxiliary drain line (I’ll explain why in other articles) it is a necessary component to keep the condensate water from backing up and over flowing into the area of the interior HVAC unit is mounted and causing minor to extensive water damage to the home.

Drain Line Rust1IF the main condensate drain line ever gets plugged up the condensate water will back up in the pan or trough (whatever the particular design of that manufacturer is) until it reaches the point where it begins to flow out the auxiliary line. The auxiliary line outlet is ALWAYS over a window, doorway or other conspicuous places. Somewhere that will make the water draining from the auxiliary drain line totally out of place. So as you tour various homes keep an eye out for that small PVC (white plastic) drain line. They are easy to spot when they’re over windows and doors.

The interior unit can be in the attic of a one story home, in the attic of a two story home, or even in a utility closet on the second floor of a two story home. If it is in a utility closet in a single story home it may drain on to the back patio next to the door, on the front stoop next to the door, I have even seen them setup to drain on to the garage floor (as effective as this location may be to spot water where it shouldn’t be it is probably the worst obvious spot possible as most of us use our garages for storage not vehicles) .DSCN2757

But the point of this article is this: IF there is water coming out of the auxiliary line of the HVAC unit SOMETHING IS WRONG. The primary drain line can be about anywhere at or near ground level but is mostly found near the exterior HVAC unit. When you spot water coming out of the auxiliary line check the primary line location. Is the ground there damp or dry? If it is damp then the blockage may only be partial and MOST LIKELY an easy fix. If it is dry the repair will probably be more extensive and expensive. If the water coming from the auxiliary drain is RUST COLORED we definitely have problems.

DSCN2639If the rust colored water from the auxiliary line is coming from the catch pan under the interior unit it is a fairly easy fix by cleaning out the primary line and replacing the pan. BUT if the rust colored water is coming out of the unit itself then we need a qualified licensed HVAC service technician to inspect, evaluate and recommend the necessary replacement or repairs the unit needs.

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