[kikifumi]

We just had an A/C unit installed. The unit is located outside. We notice that most of the lines that go to the attic in the house are covered/protected by tube foam cover and a drain pipe. However; there are 2 copper lines exposed and we wanted to know if they should be covered as well and if so, with what? We live in the northeast, so we will get rain and lots of snow.
Thank you.

[mygirlsdad77]

Usually there are only two copper lines on a ac unit. The larger line is the only one that needs to be insulated. However, on some mini split systems, both the large and small line come insulated from the factory. The insulation is mostly to prevent condensation. How many copper lines do you have on your ac system? Can you post a pic?

[KISS]

The trade name is Armaflex for the insulation. http://www.armacell.com/www/armacell...e?OpenDocument

[letmetellu]

Actually the only reason for covering the outdoor pipes is to stop condensation. Condensation in not a problem outside but in the attic or in the living area you do not want condensation forming on the uninsulated pipe and driping onto an area that can be damaged by moisture.

[kikifumi]

I do have only 2 copper lines. I can't post a pic until tomorrow. Should I buy the rubatex at Lowe's to cover them? They will be exposed to rain and snow. Thanks to all of you for your help. Very much aprreciated!

[letmetellu]

If you are going to buy a insulation buy the right size for the pipe you have. The normal size for the suction line is 5/8, 3/4. or 7/8. So buy the size that fits. Also mke sure it is a split tube with a glue on the surfaces that are going to fit together.

If the pipes are outside and the rain and snow is going to do more damage to the insulation than it will to the copper pipes.

[hvac1000]

The reason the larger (suction line) is covered is to keep the cool gas returning from the evaporator coil all the way to the compressor. The compressor needs the cool gas to keep it cool and running properly and without the cool gas the compressor will soon overheat and kick the internal overload. Note: Some refrigeration systems are designed to operate throughout the entire range without cool gas returning but not in the A/C tempersture range.

Also

Your suction line is insulated because you are trying to keep superheat controlled to properly cool the compressor, if you had a 50ft refrigerant lineset running back to the compressor you would be picking up a tremendous amount of heat in the refrigerant, and while this ensures a vapor returning to the compressor(good) it causes it to be overly superheated, a compressor should see roughly 20 degrees superheat max.

Now the liquid line is uninsulated, this allows the refrigerant to subcool as it makes its way to the indoor coil, if your liquid line is too hot you waste a tremendous amount of your "refrigeration effect"(energy) as it moves through the metering device, this is called "flashing" or "flash gas", so you want the liquid line uninsulated to allow for the most subcooling possible so less energy is wasted bringing the liquid to an evaporative state.

The insulation is also used to prevent dripping as mentioned before.

From the manual

AP Armaflex Pipe Insulation is used to retard heat
gain and control condensation drip from chilled-water

And refrigeration systems.