How To Insulate AC lines? A Complete Guide You Need

If you take a walk outside your house, you can find two copper pipes that connect the outdoor unit and indoor units of your air conditioner. These are AC lines. As a common practice, one of the AC lines should be insulated. 

Rather than hiring a pro, you can save a bunch of money by insulating AC lines yourself. This post will guide you on insulating these lines and answer a few questions related to this topic.

Let’s begin!

What type of AC lines requires insulation?

There are two types of air conditioner refrigerant lines: the suction line and the liquid line. However, only suction lines need to be insulated. 

See also what AC suction lines are and what AC liquid lines are.

You may wonder why you should add insulation to your AC suction lines.

This is because the suction line carries the cold, gaseous refrigerant from the evaporator to the condenser. If not insulated, the moisture in the ambient environment will cause the line to sweat, and the temperature of the refrigerant will increase, affecting the thermal efficiency of your AC system.

In other words, adding insulation to the suction line can increase the cooling effect of your air conditioning unit. 

Since the liquid line transport warm liquid refrigerant and needs to shed heat, it doesn’t require any insulation. 

The importance of inspecting insulation on the AC system regularly

Even if the HVAC technician has added insulation to your AC lines, it doesn’t mean you can rest easy and leave it unattended. 

In fact, you should check the insulation at the beginning of each cooling season to ensure your AC has good performance. 

Exposure to the sun, bad weather, poor installation, or even rodents cause the insulation to break, reducing the thermal efficiency and even causing refrigerant leaks. That is, you will need to pay more electricity bills but the room temperature will not drop as quickly as before.

This is no single clear-cut answer to how often you should replace it. A general rule of thumb is that you should replace it once you notice the insulation of the AC lines starts to degrade. 

In my experience, the insulation can usually last more than five years.

What kind of insulation is appropriate for AC lines?

There are three common types of insulation material: polyethylene foam, rubber foam, and fiberglass. Polyethylene foam is most people’s choice when it comes to adding insulation to AC lines.

This is because polyethylene foam is light on the pocket and easy to cut and install. You can learn how to install it immediately, even if you have no experience. 

How to insulate AC refrigerant lines?

Now that you have a basic understanding of AC line insulation let’s start to learn how to insulate it exactly. 

how to insulate ac lines

Step 1: Remove the broken insulation

You can’t remove the old insulation by hand. Wear gloves, use a utility knife to remove it, and ensure you don’t hurt the cold line inside.  

Step 2: Measure the length of the suction line and thickness of the old insulation

Insulation that is too short or too long is not a suitable choice. You should measure the refrigerant line’s length and outer diameter and ensure the insulation added is about ½” longer than the line. 

On top of it, you should measure the thickness of the old insulation or check the R-value of insulation recommended in your area.

Step 3: Shop for the proper insulation

After having the correct measurements, you can go to a local store and get the proper insulation you need. Don’t forget to grab some electrical tape if you don’t have one. In my experience, the clerk will know what you need. 

Step 4: Turn off your AC and wait for a while

I know how miserable you will be without an air conditioner running, but you should turn it off when installing insulation. 

In addition, you should wait until the temperature of the suction line has risen, and no condensation will form on the surface of the pipe.

Since the pipe is exposed to the elements, it might be dusty. It would be best if you wiped it down so that no mold and mildew would grow inside the insulation. 

Step 5: Install the insulation 

Finally, you can start to insulate the lines. After wrapping the insulation around the pipe, you must remove the protective backing on the slits and tightly press the sticky edges. 

Step 6: Wrap the foam insulation with tape

insulate ac lines with tape

If you want to make the insulation last longer, I highly recommend you wrap it with tape. Actually, I found that HVAC experts will wrap all the lines together with electrical tape when installing the split air conditioner. 

Sum up 

This post has summarized pretty much everything you need to know about insulating AC lines. Because suction lines are cold, adding insulation to them can prevent moisture buildup and enhance the cooling effect of your AC. 

While an HVAC expert can definitely handle it, you can insulate it on your own easily. Once you can the proper insulation material, you can wrap it around the pipe and then cover it with electrical tape. 

I hope this guide will help you out.

About The Author

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Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested dozens of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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