How To Replace Worn Or Damaged Insulation On Your Central Air Conditioning System's Refrigerant Line

22 May 2015
 Categories: Construction & Contractors, Articles


As warm weather approaches, it is time for many American households to turn on their central air conditioning systems. Before doing so, however, it is good to take a close look at your system to ensure it is ready to provide efficient, effective cooling all summer long. One cooling and heating repair area that you may not have noticed in the past is the insulated hose that runs from your outdoor compressor/condenser unit. If its insulation is cracked, damaged or missing altogether, you will need to replace it. Below is more information on what this hose does and what you need to do to protect it with new insulation:

A tale of two hoses

With a central air conditioning system, the outside unit houses your system's refrigerant compressor and condenser. The compressor forces liquid refrigerant into the home via a high-pressure line, and the condenser accepts refrigerant vapor through a suction line. Identifying the lines is easy; the high-pressure line is small in diameter and warm to the touch, while the suction line is larger in diameter and cold to the touch.

Ideally, the suction line should be completely insulated on its path from the inside evaporator to the condenser. However, in locations where the suction line is outside, the insulation is often found failing due to neglect. Insulation serves two important purposes:

  • Prevents condensation from forming on the suction line – suction line condensation can be a headache for homeowners. It can cause potentially-dangerous slip hazards, and it is also destructive to the home's building materials. Wood rot is just one example of what can be caused by a suction line's condensation run-off.
  • Prevents the vaporized refrigerant from absorbing heat – the insulation on the suction line protects the refrigerant vapor from absorbing heat from the ambient air. Unnecessary heat absorption only causes the compressor to work harder, which in turn results in higher energy costs and shortened equipment lifespans.

Replacing the insulation – what you will need

Fortunately, line insulation replacement is an easy fix for almost any homeowner, and its low cost is more than made up for by gains in efficiency. Below are the materials and tools you will need to remove the old insulation and replace it with new:

  • Replacement elastomeric insulation – this consists of a hollow foam tube that encases your suction line. To determine what size you need, measure the length of the suction line from the outside unit to the point where it enters your home. Next, measure the diameter of the line at a non-insulated point. Elastomeric insulation is available in varying thicknesses, but you should choose the widest thickness you can find for the appropriate matching line diameter.
  • Aluminum foil tape – be sure to find a tape that is rated for water-resistance, and do not use duct tape or a similar product since they will break down under exposure to heat or moisture.
  • Shop towel or similar rag
  • Utility knife

Replacing the line insulation – how it's done

Once you have your materials in place, you are ready to begin:

  1. Turn off your air conditioning unit – you will have difficulty removing condensation that may accumulate on the suction line if it is operating.
  2. Cut away old insulation
  3. Clean the suction line – wipe down the suction line to remove water, tape residue or other debris. It doesn't need to be squeaky-clean, but your insulation will better fit if the surface of the line is not wet or full of debris.
  4. Prepare the new insulation – some line insulation comes with a pre-cut slit that runs the length of the tube. If your product does not, carefully make a long straight cut down one side of the tube.
  5. Install the insulation – slightly unfold the insulation along the slit, and press it into place over the suction line. The natural "spring" in the foam should close the gap. Adjust the insulation so it evenly covers line without kinking or twisting. Cut away any excess length with the knife.
  6. Tape the insulation – with the aluminum foil tape, begin wrapping at one end of the line in a corkscrew pattern so that tape covers all the exposed insulation. Apply a little extra tape at each end of the insulation to hold it in place on the line. Don't squeeze too tightly when applying the tape, or you will lose some of the insulating value by compressing air out of the foam's cells.

If everything was done properly, your suction line's insulation should last for a long time; the tape will protect the foam from rotting plus reflect heat away from the surface of the insulation.