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Look for Condensate Drain Line Insulation

Materials Cost: FREE
Difficulty Level: 1

Introduction

Look at the condensate drain line of your air conditioner, heat pump, or condensing furnace or boiler to make sure it is insulated. 

Why

In jurisdictions in hot humid climates, the local building codes often require that the horizontal condensate line pipes that are located in unconditioned areas (like attics) should be insulated to prevent condensation from forming on the exterior of the drain pipe. The condensate line from an air conditioner can be quite cool. When hot humid attic air touches the cold pipe, water vapor can condense on the pipe. This water can drip onto surrounding surfaces like attic insulation, wood framing, and ceiling drywall, where it can encourage mold growth and where, over time, it can cause water damage to the materials. In cold climates, condensate lines should be insulated to prevent freezing of the pipes. 

What You'll Need

  • Lighting (headlamp, flashlight)
  • Ladder to get into the attic if there is no pull-down attic ladder.
  • Camera/phone to take pictures
  • Pipe insulation (optional)

1. Find the air handler and the condensate drain.

Your air handler (furnace and air conditioner, central heat pump, or condensing furnace or boiler) might be located in the attic, basement, garage, or a utility closet inside the home. The condensate line will be made of PVC or plastic and it should drain to the outside or to a house drain that goes to the sewer. Figure 1 shows an air conditioner in an attic. The condensate line is the pipe going from the air handler at right down and off the left side of the picture. Figure 2 shows another air conditioner located in an unconditioned attic with an uninsulated condensate line that is showing visible condensation on the horizontal pipe and signs of condensation like wet wood beneath the elbow. 

Figure 1. This air conditioner is located in an unconditioned attic and has a condensate line that is uninsulated (Source: PNNL).
Figure 2. The uninsulated condensate line on this air conditioner located in an unconditioned attic is showing signs of condensation including wood staining at the elbow, discoloration at the joint, and liquid condensation on the pipe (Source: PNNL).

2. Look for condensation.

Look for active condensation (water droplets on pipes) and signs of past evidence of condensation (water stains on wood or floor) (Figure 3 and Figure 4).

Figure 3. Condensation droplets are clearly seen on this uninsulated condensate line from an air conditioner located in a hot humid attic (Source: PNNL).
Figure 4. Condensation has dripped onto this board and drywall from an uninsulated condensate line on an air conditioner located just above the photo in this unconditioned attic; the water pooling on the drywall will likely soon become evident from below as water spots on the ceiling (Source: PNNL).

3. Insulate the pipes.

When you examine your equipment, if you find evidence of current or past condensation on the condensate line, then insulate the horizontal runs of the condensate line with pipe insulation as shown in Figure 5 or hire an HVAC contractor or handyman to insulate the pipes. 

Figure 5. The condensate line on this air conditioner has been covered with pipe insulation (Source: PNNL).

Additional Info

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Disclaimer

This content is a work created with funding provided by the United States Department of Energy under Contract no DE-AC05-076RL01830 for the operation of Pacific Northwest National Laboratory. The information and guidance provided by Pacific Northwest National Laboratory (PNNL) in the content are intended solely for educational purposes only and do not constitute formal training or certification. It is provided with the explicit understanding that neither the United States Government nor the United States Department of Energy, nor the Contractor, nor any or their employees, nor any jurisdiction or organization that has cooperated in the development of these materials, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness or any information, apparatus, product, software, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or Battelle Memorial Institute. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Viewers assumes full responsibility for all actions that they may take from information provided in this content including ensuring the safety, code compliance, and proper functionality of any products they choose to install. Installation and use of such products should be performed in accordance with local regulations and manufacturer instructions.