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7 Answers 7

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This is the answer to your actual question:



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From this site:

"the skinny tube doesn't need insulation"

From another source:


The following site provides good step by step maintenance instructions.

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Suction Line Insulation

Insulating the suction line (larger pipe) is done for two reasons. First, it prevents condensation forming on the pipe. Condensation could drip from the pipe and cause damage to building materials, or create a slip hazard on the floor. The other reason to insulate the suction line, is to prevent the refrigerant in the line from picking up additional heat. The warmer the refrigerant is, the harder the compressor and condenser have to work. Minimizing the temperature of the refrigerant in the suction line, helps the condensing unit work more effectively.

Liquid Line Insulation

To avoid going off topic to explain metering, I'll just say that depending on where the metering takes place, you may or may not have to insulate the "liquid" line.

Metering in the outdoor unit

If the metering device is in the outdoor unit, you're going to want to insulate the line. The refrigerant in the line is ready to flash (boil), so adding too much heat could cause it to flash before it reaches the coil.

Metering in the indoor unit

If the liquid line is a true liquid line, and the metering device is inside near the coil, then there's no need to insulate it. A slight change in the temperature of the refrigerant, isn't going to make much of a difference. Consider that it takes 1 Btu to change one pound of 211° water to 212° water, but requires 970.4 Btu to change one pound of 212° water to 212° steam. As you can see, it's the change of state where the real cooling takes place. Because of this, changing the temperature of the refrigerant a few degrees in the liquid line doesn't make much difference.

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If you are a diy'er like myself and not an air conditioning expert, realize that insulating external piping does allow for the most efficient operation and does not have to be complicated. On my outside unit I could not get regular split-form insulation to stay in place and not deteriorate rapidly where the unit is exposed to the sun. I took a serrated blade and cut a slot down the length of a few of those swimming pool float tubes so that I could slip them over the exposed metal parts of the condenser pipes. I then put a few turns of duct tape around the tube every 6 inches or so to close the slit in the tube and to prevent the whole thing from sliding around in the weather. The regular AC maintenance service checked things on its next visit and found no problem with it and I have had no problems with the piping since.
Good luck.

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Hot water pipes will also benefit.


Closed cell foam with adhesive

Open cell, no adhesive

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protected by Community Jul 19 at 15:23


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