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Look at Refrigerant Line Set Insulation for Air Conditioners or Heat Pumps and Replace if Needed

Materials Cost: FREE
Difficulty Level: 1

Introduction

Look at the condition of the insulation on the refrigerant pipe from the house to the outdoor unit of the home’s air conditioning or heat pump system and replace or hire an HVAC contractor to replace if needed.

Why

Air conditioners and heat pumps use a refrigerant like freon to move heat out of the home in cooling mode. For heat pumps, this cycle is reversed in winter to bring heat into the home. This refrigerant moves from the evaporator coil in the air handler located inside the home to the outside compressor/condenser unit and back again. The exposed portion of the refrigerant line should be insulated to protect it from damage and improve the efficiency of the system. The pipe insulation keeps the refrigerant in the correct state or phase, minimizes energy losses, and prevents condensation. The condition of the pipe insulation should be examined annually to make sure it is not worn, cracked, or damaged. 

What You'll Need

  • Camera/phone to take pictures 
  • Pipe insulation or refrigerant line insulation kit 
  • Zip ties or tape 
  • Weather-resistant tape or vapor barrier “jacket”  
  • Utility knife 

1. Locate the refrigerant line.

If you have central air conditioning or a heat pump, the system has an indoor unit and an outdoor unit. The indoor unit has a fan to blow the conditioned air into the ducts that distribute the cooled (or heated) air throughout your home. The outdoor unit contains the compressor, condenser, and condenser fan. Locate this outdoor unit and you'll see two refrigerant pipes coming from it to the house – a thicker line encased in insulation and a thinner copper line that typically has no insulation. The large line carries cool gas refrigerant and is called the suction line, return line, or vapor line. The thinner line carries hot liquid and is called the liquid line or discharge line. Air conditioning or heat pump systems that have an expansion valve in the indoor unit (this includes most “central air” ducted systems) only need the thicker pipe insulated. However, systems that have the expansion valve in the outdoor unit (this includes most ductless “mini-split” heat pumps) need to have both the thicker pipe and the narrow pipe insulated, because on these systems the narrower pipe gets colder potentially leading to condensation wherever the narrow pipe goes through walls, crawlspaces, or attics if that pipe is not insulated.    

2. Look at the pipe insulation.

Look at the condition of the pipe insulation on the larger line. Because this refrigerant pipe insulation is located outside, it can degrade quickly, depending on how much exposure it gets to sunlight and extreme weather conditions. Check the lines annually to make sure the insulation is still in place and to look for damage and wear (Figures 2 through 5). You can also check to make sure the inside refrigerant line going from the HVAC unit to the wall is insulated (Figure 6). That refrigerant line is not likely to be subject to harsh weather conditions but it should still be insulated to reduce the incidence of condensation and to improve system efficiency.  

If the insulation on the exterior refrigerant lines is cracked or missing (like we see in Figures 2 through 5), call an HVAC contractor to replace the refrigerant line insulation with a durable solution or replace it yourself using the following the steps.  

If you choose to replace the insulation yourself, you will need to find pipe insulation of the correct diameter. Pipe insulation for ½-inch, ¾-inch, and 1-inch diameter pipe is readily available at hardware stores since these are also common sizes for water pipes. However, the refrigerant lines on air conditioners and heat pumps might be in other sizes such as ¼”, 3/8", 5/8", or 7/8" sizes. Also, most pipe insulation available at home improvement stores is not outdoor- or UV-rated and thus must be wrapped with line set tape. HVAC professionals shop at supply distributors that stock pipe insulation specifically for refrigerant lines so they can easily access pipe insulation that perfectly fits all of these refrigerant pipe sizes and that comes with a UV-resistant outer jacket. For this reason, it might be easier to ask an HVAC contractor to handle this project. 

Figure 1. The pipe insulation on this exterior refrigerant line is intact but significantly degraded from ultraviolet (UV) exposure (Source: PNNL).
Figure 2. This refrigerant line pipe insulation has been significantly degraded by exposure to the weather and needs to be replaced (Source: PNNL).
Figure 3. This refrigerant line was correctly insulated and wrapped with a weather-resistant covering but the tape covering is losing its adhesion due to exposure; pipe insulation should be checked annually for wear (Source: PNNL).
Figure 4. When it comes to refrigerant line insulation, the 80-20 rule does not apply! Insulate the whole pipe (Source: PNNL).
Figure 5. The inside refrigerant line leading from the air conditioner or heat pump to the wall should be covered with pipe insulation and a vapor barrier to reduce condensation potential and improve system efficiency (Source: PNNL).

3. Remove the old pipe insulation.

Using a utility knife and scissors, remove the old insulation (Figure 6). Be careful not to cut, bend, or twist the refrigerant line or any electrical wiring wrapped around it. 

Figure 6. Remove and replace the old insulation on the refrigerant line of your air conditioner’s compressor unit if the insulation becomes cracked or damaged (Source: PNNL).

4. Install new pipe insulation.

Install new pipe insulation on the refrigerant pipe. Measure the pipe diameter to determine what size insulation you will need. You can use ordinary foam pipe insulation which is made of closed-cell foam and manufactured with a lengthwise slit for easier installation, if you can find the right size, or you can use a pipe insulation with a UV-resistant covering specifically made for exterior refrigerant lines as described in Step 5. This product may come with self-adhesive strips on each side of the slit. After sliding the pipe insulation into place, peel off the plastic protecting the adhesive strips and press the edges together. (Figure 7).  

Figure 7. Install new insulation on the refrigerant line of your air conditioner’s compressor unit to protect the pipe and improve your cooling system’s efficiency (Source: PNNL).

5. Cover pipe insulation with UV protection.

In addition to insulation, the refrigerant pipe needs a UV- and weather-resistant covering for additional protection against the sun and harsh weather. You have several options.  

You can wrap the pipe insulation with a weather-resistant and UV-resistant tape (Figure 8). Start at the lowest end of the pipe and work your way up in overlapping wraps so that any rainwater that hits the pipe will roll off the tape and not work its way under the tape. 

Figure 8. The new pipe insulation on these heat pump refrigerant lines is wrapped in UV-resistant tape starting from the bottom and working up; the tape layers are shingled to prevent water entry (Source: PNNL).

Rather than covering the entire exposed length of pipe with tape, one option is to purchase and install a ready-made UV-resistant vapor-barrier jacket specifically made for refrigerant line sets (Figure 9).  

Figure 9. A ready-made UV-resistant jacket is installed over the pipe insulation on this AC refrigerant line for additional protection against the sun and harsh weather (Source: PNNL).

Another option is to buy a pipe insulation that comes with an integrated vapor barrier layer on the outside of it (Figure 10). Install per manufacturer’s instructions. 

Figure 10. This pipe insulation for air conditioner and heat pump refrigerant lines comes with an integrated UV-resistant vapor barrier layer for protection against the sun and harsh weather (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.