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  1. #1
    HappyCamper's Avatar
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    Maximizing the warmth of a down underquilt

    I'm still trying to figure out the best way to maximize the warmth of my down underquilt in below freezing temps. Many are reporting low temperature hangs right now. And I see many of us using closed cell pads or windshield reflectors between our bodies and the down underquilts. (I'm not talking about leg pads with short quilts.) Is this maximizing the down warmth factor? Doesn't the down work off the warmth of our bodies and if we put a ccf pad between us and the down, doesn't that simply block the heat getting to down and keep us as warm as possible?

    Should we be using CCF pads between our upper bodies and the down quilt? I'm confused?
    Exercise, eat right, die anyway -- Country Roads bumper sticker
    Fall seven times, standup eight. -- Japanese Proverb

  2. #2
    Senior Member Quoddy's Avatar
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    I believe that most of your assumptions are correct. If an underquilt is good to zero, then adding a ccf pad above it does little, if anything, to improve the temperature rating. It almost amounts to having additional airspace in between which reduces the warmth of the UQ. I don't scientifically know if it reduces the warmth, but I'd suspect that it doesn't improve it any.
    I my Warbonnet

  3. #3
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    Quote Originally Posted by HappyCamper View Post
    I'm still trying to figure out the best way to maximize the warmth of my down underquilt in below freezing temps. Many are reporting low temperature hangs right now. And I see many of us using closed cell pads or windshield reflectors between our bodies and the down underquilts. (I'm not talking about leg pads with short quilts.) Is this maximizing the down warmth factor? Doesn't the down work off the warmth of our bodies and if we put a ccf pad between us and the down, doesn't that simply block the heat getting to down and keep us as warm as possible?

    Should we be using CCF pads between our upper bodies and the down quilt? I'm confused?
    No, a down quilt or any insulation merely slows down the flow of heat. Adding more insulation than you need can result in overheating/perspiration so in that sense it is undesireable. Your UQ wouldn't get wet but your top quilt might lying on a CCF pad. Other than that, there is no "harm". SGT Rock use two Oware evazote pads and a JRB UQ on his thru and it worked great for him.

  4. #4
    MacEntyre's Avatar
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    Insulation provides resistance to heat conduction. The more resistance you have, the more temperature difference is required to lose a given amount of heat over a given time. To optimize your heat retention, you should put the best insulator at the hottest surface (your hammock), so that it's resistance to heat conduction will give you the lowest rate of heat loss at that point, where you value heat the most. That would be the CCF pad. But the optimal solution is somewhat academic. The total resistance remains the same, no matter where you put the CCF.

    Putting the CCF pad outside the down (assuming you have no air gaps) will add the same resistance to heat conduction as if it were added to the inside. However, I think the warm feeling we get from down is because it is relatively thick, and our heat loss warms it up as is passes through the down. When you shift positions, the down doesn't get cold as fast as other insulators. It feels warm and deep because it is!

    You can look at insulation the way Grandma viewed the water supply, when she spit in the well and said, "Every little bit helps!"

    - MacEntyre
    Last edited by MacEntyre; 01-08-2010 at 16:10.
    "We must, indeed, all hang together or, most assuredly, we shall all hang separately." - Ben Franklin
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  5. #5
    Senior Member Mrprez's Avatar
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    Quote Originally Posted by MacEntyre View Post

    You can look at insulation the way Grandma viewed the water supply, when she spit in the well and said, "Every little bit helps!"

    - MacEntyre
    Eeeewwwww! Grandma!

  6. #6
    Senior Member SmokeHouse's Avatar
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    Quote Originally Posted by HappyCamper View Post
    I'm still trying to figure out the best way to maximize the warmth of my down underquilt in below freezing temps. Many are reporting low temperature hangs right now. And I see many of us using closed cell pads or windshield reflectors between our bodies and the down underquilts. (I'm not talking about leg pads with short quilts.) Is this maximizing the down warmth factor? Doesn't the down work off the warmth of our bodies and if we put a ccf pad between us and the down, doesn't that simply block the heat getting to down and keep us as warm as possible?

    Should we be using CCF pads between our upper bodies and the down quilt? I'm confused?
    I was wondering about this too since alot of us on HF has gotten this very nice blast of cool air. I'm going out tonight and tomorrow night and do some testing. I know its going to be around 0F or lower for the next 2 nights. Thought I would try the MW4 tonight and add a gg1/4 pad tomorrow night to see if I can feel a difference... Wife thinks I'm crazy,,, ... maybe so, be it will be fun...

  7. #7
    Knotty's Avatar
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    Unfortunately there are so many myths and misconceptions about insulation.

    Fortunately there are also Take-a-knee and MacEntyre!
    Knotty
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  8. #8
    Senior Member pizza's Avatar
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    Quote Originally Posted by Quoddy View Post
    I believe that most of your assumptions are correct. If an underquilt is good to zero, then adding a ccf pad above it does little, if anything, to improve the temperature rating. It almost amounts to having additional airspace in between which reduces the warmth of the UQ. I don't scientifically know if it reduces the warmth, but I'd suspect that it doesn't improve it any.
    That's been my experience. I felt cold this past fall using a full length pad in the hammock in conjunction with my Yeti 3 season underquilt but when I trimmed the pad and just used it under my feet and then the quilt by itself on the torso I was definitely warmer.

  9. #9
    MacEntyre's Avatar
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    Quote Originally Posted by Knotty View Post
    Fortunately there are also Take-a-knee and MacEntyre!
    You're far better served reading what Take-a-Knee writes...

    "We must, indeed, all hang together or, most assuredly, we shall all hang separately." - Ben Franklin
    www.MollyMacGear.com

  10. #10
    Senior Member Oh-No's Avatar
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    Heat moves via. conduction, convection, and radiation.
    Simple examples:
    1- Conduction- heat moving through your aluminum pot to the water inside.
    2- Convection- heat transfered by moving gas or liquid. Think wind chill.
    3- Radiation- the sun

    Most of our insulation is designed to minimize the
    first 2. I'll let others tackle Radiation (think space blankets)

    Down is a poor conductor of heat and fairly good at reducing convection.
    CCF is a better conductor (not a good thing) than down, but is better at reducing
    heat flow by convection than down.

    So back to your question: should the CCF pad be on the inside or the outside?
    I think it should be on the inside not because of insulation factors but because it
    is a vapor barrier. Vapor barriers should be close (if not next) to the heat & moisture
    source which is you.

    If water was not an issue, perhaps the down next to you would be best because
    it form fits better. Fewer and smaller gaps between you and the insulation reduces
    convective heat loss. It's hard to wrap CCF around you and not have air gaps.
    But I'd like to hear from others who aren't trying to remember their physics
    course info. from 35 years ago. :-)

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