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Heat Trace PEX?

kkrrjr Member Posts: 12
I have a friend ( no really it's not me) with some frozen pipes in North Carolina. They are PEX and were run in an outside soffit. They have frozen twice in the last two cold snaps.

Is it OK to heat trace PEX? I see where the heat trace manufacturers say its OK for plastic but they didn't mention PEX specifically.


  • icesailor
    icesailor Member Posts: 7,265
    Icy PEX:

    Remember, there are more than one type of heat tape, The flat heat tape if covered with insulation can burn down a house if the instructions are not followed precisely. Do not under any circumstances, cover it with rubber type (Arma-flex) insulation. If it overheats, it can catch fire. Usually in the middle of the night.

    Just because Wilmington, NC is on the same Latitude as Los Angeles, CA, doesn't mean that you should pipe houses like you are in LA.

    Even if you insulate the pipes, they will still freeze if the water is standing. When really cold and at or below freezing, run water through a fixture that the water will go through the effected pipes. It doesn't have to be fast. At the speed where it goes from a "drip-drip" to a very small, steady stream.

    A tip to those on the edge of "The Northern Tier". When it is cold and freezing out, run water in the hot and then cold taps. Put your hand under the flowing water. If you feel the water get so cold that it hurts, then warms up again, you have cold air on the pipes and they will freeze. Its far cheaper to let the water run slowly and pay for the wasted water than to have to fix broken pipes and damaged houses.

    There's nothing so refreshing as going to a house to meet the caretaker and finding a large section of the North side as a sheet of ice, and going inside to find water rushing down the stairs like in the Disney movie "The Sorcerer's Apprentice". And finding the water half way up to the second step in the cellar that is 28' X54' and the Caretaker tells you he checked the property at 3:00 PM today. Living room ceilings on the floor are refreshing too.

    Lets see, it is warming up after a cold spell, it has a 12 GPM water pump, the cellar has 1 1/2' of water, 28' X 54', how many cubic feet of water is that? 7.5 Cu. Ft per gallon. How much water does a 12 GPM pump in an hour? Do the math.
  • Anarchist1
    Anarchist1 Member Posts: 3
    Totally agree with never insulating the wrapped lines. I had a new customer, restaurant and their walk in freezer receptacle in the freezer was tripping the GFI all the time. Another "Refrigeration" company wrapped the new heater cable around the copper drain line for the freezer coil and wrapped it with 1" thick insulation to "help keep it from freezing". It was shorting out on the copper drain line from overheating so much. I installed new heater wrapped with 1/2 "spacing and NO insulation. It's been months and no freezing of the drain. Also, removed the receptacle and put in watertight junction box.
    If you want to run copper pipes and wrap with trace heater with thermostat you might be able get away from running water all the time.