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Thread: Insulating and clamping PEX lines

  1. #1
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    Insulating and clamping PEX lines

    When a pipe is both clamped and insulated, do the clamps go over the insulation or does the insulation go around the pipes except where they are clamped? -

    I want to insulate PEX lines that are to be clamped to a garage wall. Is there a type of clamp that will hold the line far enough away from the wall so that an insulating foam sleeve will fit all the way around the line?

  2. #2
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    Continuous, uncompressed insulation is always going to be better than insulation with breaks for clamps, so clamps over would be my choice. You should be able to easily source larger clamps that are for pipe that is just at or hair under the outside diameter of insulation. Unlike metallic or hard plastic pipe, PEX doesn't have to be super tight to the structure because of its inherent flexibility.
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  3. #3
    PEX doesn't have to be super tight to the structure because of its inherent flexibility.
    To "expand" on Jim's point a bit: you don't want pex clamped tightly because it expands and contracts with temp changes more than, say, copper. So pex clamps are designed to allow some movement without making noise. So lightly clamping over continuous insulation would be a good way to go.

  4. #4
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    There are a million types of plastic PEX snap in hangers any of which you could stand off the wall slightly to allow for the insulation to wrap the tubing. The hanger goes around the pipe, not around the insulation. The insulation is notched around the hanger. Im not sure of any/many variable standoff hangers that allow you a given distance from the wall for the thickness of insulation you plan to use. That would seem to have to be achieved by other means. I had a friend who was an insulation junkie and insulated his PEX with standard pipe insulation with an i.d. to fit the o.d. of the PEX and then put like 1 1/2" ID insulation over that (double layer). Was a stellar job. What it saved I have no idea.
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  5. #5
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    Mark, I would think that the primary focus of insulating the PEX in the OP's garage is to protect against freezing in the winter and insure that the cold line (if applicable) stays cooler in the summer if this is unconditioned space. I see no reason that one would have to use PEX specific clips "inside" the insulation for this particular application and personally would use some other type of pipe clip appropriately sized over the insulation so that there was no break in the insulation at the clips.
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  6. #6
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    Quote Originally Posted by Jim Becker View Post
    Mark, I would think that the primary focus of insulating the PEX in the OP's garage is to protect against freezing in the winter and insure that the cold line (if applicable) stays cooler in the summer if this is unconditioned space. I see no reason that one would have to use PEX specific clips "inside" the insulation for this particular application and personally would use some other type of pipe clip appropriately sized over the insulation so that there was no break in the insulation at the clips.
    Maybe so. In my 30 years of plumbing and running all kinds of pipe from pex on down Ive never known a situation where you "clamp" the insulation. It would be akin to trying to clamp a marshmallow. Your objective with hanging pipe of any kind is to contain the pipe and allow for any movement the specific pipe requires. Even in heavy industrial applications the pipe is hung/clamped and the insulation is applied and cut around any needed hanging.

    No idea if his pipe in the garage is from a water heater or a cold water line or not.
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  7. #7
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    Or insulate with foam sleeves and put the whole thing in a cable tray with no clamps. The way I ran ac drain line under my house was hole through the joist then an insulation sleeve that butted tight to the joist and so on. You could nail on short pieces of 1X lumber sticking out with holes drilled in each piece.
    Bill D

  8. #8
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    Mark, for heavier pipe, I don't disagree, but PEX by itself is pretty light and there are advantages to having un-interrupted, un-compressed insulation...the combination is an opportunity I think given the materials involved. I'd never do this with copper or heavier PVC/ABS, however.
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  9. #9
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    i recently had to do this. i used the pipe sleeve insulation and bought 2 in conduit straps, they fit perfect over the insulation, i used 1 in pipe insulation on 3/4 pex. the clamps did not compress it and hold it nicely and neatly to the wall. it looks quite professional actually.

    i would not notch them, as continues, air sealed, insulation is much better. i taped all the joints and got the pipe sleeves with the sticky on the "slot". I also have heat tape on a thermostat in the insulation as a safety measure.

    my situation is to protect it from freezing, In NM maybe that is not as much of a concern.

    I had zero other options to run a new water line to a part of my home on the other side of the unheated garage after my waterline from the street needed to be replaced due to a massive leak. the original line had a T somewere to go to that side, but there was no way to get a new line into the space without tearing out my whole driveway and part of the interior concrete floor. another 15K for the digging and replacement ontop of what i spent on 150 feet of water line already, or 300 bucks of supplies to run a new line through the garage attic.
    Last edited by Adam Herman; 12-04-2019 at 1:01 PM.

  10. #10
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    Quote Originally Posted by Jim Becker View Post
    Mark, for heavier pipe, I don't disagree, but PEX by itself is pretty light and there are advantages to having un-interrupted, un-compressed insulation...the combination is an opportunity I think given the materials involved. I'd never do this with copper or heavier PVC/ABS, however.
    Again, in 30 years of inspected work I just honestly have never come across a situation where you would be clamping around the outer diameter of some form of insulation. I may well be what some do but you typically hang your "pipe". You dont hang your "pipe wrapped in some form of insulation" though the logic is clear.

    It would undoubtedly be fine. If your in an inspected situation Im not sure it would fly on mass.
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  11. #11
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    When I was doing installs for Revco and CVS the pipes had to be open for inspection then insulated after

  12. #12
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    Quote Originally Posted by Jim Becker View Post
    Mark, for heavier pipe, I don't disagree, but PEX by itself is pretty light and there are advantages to having un-interrupted, un-compressed insulation...the combination is an opportunity I think given the materials involved. I'd never do this with copper or heavier PVC/ABS, however.
    Again, do what-cha-like where you can. As I said, pipe of any kind, land yourself in an inspected situation and you likely may not be flying past having hung on insulation. The goal is to hang the pipe. Not leave it dangling in a loose hanger when and if the day comes that the insulation is not what it was when you clipped it.

    I dont disagree that the convenience of not having to cut around hangers and having continuous insulation would seem logical. That said, you still hang your pipe. The weight and movement of any pipe over time is going to eliminate the insulation around the hanger over time anyway. It will compress it, cut through, and so on. You hang your pipe whether it be a condensate line or a 4" process steam line.
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  13. #13
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    There is sort of an exception to always insulating around the hangers. The pipe in my building (historical courthouse, 4-pipe heating/cooling), is largely suspended from ceilings. The pipes are run over suspended uni-strut. Between the pipe and the uni-strut are a block of wood (larger pipes, smaller pipes omit the wood) and a galvanized steel saddle. The insulation is cut to fit tightly around the supporting block of wood, or, in the case of the smaller pipes, the insulation (foam rubber) provides the support. Since this installation is ~27+ years old, we're finding that the foam rubber is aging, and on the chilled water lines (~45F) it's compressing enough to cause condensation to form on the saddles on humid days. From the insulating contractors we've had in from time to time, I'm told this is all common and normal.
    Jason

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  14. #14
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    Jason
    Just curious, but why 45 chilled water? In my HD industrial experience, 55 was our norm to cool and dehumidify. It also saved a lot of energy.
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  15. #15
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    Quote Originally Posted by Myk Rian View Post
    Jason
    Just curious, but why 45 chilled water? In my HD industrial experience, 55 was our norm to cool and dehumidify. It also saved a lot of energy.
    Your guess is as good as mine. That's what our two 170-ton chillers were set at when I arrived 4.5 years ago (actually closer to 43-44F at the chillers), and I haven't changed them. My assistant director is HVAC-certified (came out of Eli Lilly maintenance background), and has said he would prefer colder. The chillers are somewhat remote--the length of 6" circulating supply line is probably over 600' away underground, or a block and a half via the street and alley. I'm no HVAC engineer, so I let sleeping dogs lie (mostly). We just had a $700,000 HVAC upgrade on our top floor, and the design engineer seemed to act like the lower temp was perfectly normal. On the new air handlers, the delta-T is almost 20F even right now in the chilled water coils, so I can't imagine warmer would work too well.
    Jason

    "Don't get stuck on stupid." --Lt. Gen. Russel Honore


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