Feb 14, 2007 at 8:01 am #1221829
So I just got one of these and used it for the first time this past weekend. Everyone seems to love theirs and I agree that the comfort aspect of it is better than any other. However, I hate to say it but I experienced cold spots all night on both nights of using it. Temp dropped to 25 the first night and 20 the second night. I noticed I was fine as long as I stayed still but the minute I rolled over, I felt cold spots. My only guess is that my body warmed the tubes I was on top of, but when I rolled over to another one, it was cold and not warmed by my body. When blowing this up, I notice it slowly inflates TUBE BY TUBE, not all one mass. This leads me to believe that each tube is almost separarately warmed rather than the entire pad being treated as one large air mass that shares warmth. Is mine defective or is this normal? Can anyone advise on this? Thanks a lot!!Feb 14, 2007 at 8:54 am #1378449
Mark VerberBPL Member
@verberLocale: San Francisco Bay Area
Your experience of the tubes functioning pretty much independently is right. That isn't necessarily a bad thing since it restricts convection within the pad.
I haven't notice cold spots when rolling, but part of this is that I tend to end up in the same location once I am done moving, and during the moving I am more aware of drafts that my quilt is letting in while I am disrupting things.
–markFeb 14, 2007 at 9:22 am #1378456
Rick DreherBPL Member
@halfturboLocale: Northernish California
I suppose it's possible that air in the individual tubes is heating to differing degrees (sorry, bad pun) and when you turn you're mixing the air among the tubes, instantly cooling the warmer ones.
I think it's important to note that significant convection heat-loss is occurring inside the tubes all the time, and you're only being insulated by a fiberfill layer about a quarter-inch thick atop the mattress. I love the physical comfort of these things, but find my lower limit to be only to the 40s–perhaps 10 or charitably 15 degrees better than a plain air mattress. I recommend a thin foam torso pad on top in temps any lower (countering the mattress' compactness).Feb 14, 2007 at 10:09 am #1378467
Do you suppose it would help boost the temperature range significantly if I were to lay it on top of a Thermarest Z-lite or compareable closed cell matt?Feb 14, 2007 at 10:46 am #1378473
Mark VerberBPL Member
@verberLocale: San Francisco Bay Area
I appreciate that Rick finds that this style of pad is only good down to 40F. My experience has been that it's been completely comfortable down to 20F. The BA Insulated Air Core which seems to have simular performance characters is R4.1 which is more insulate than most three season closed cell and self inflating mats.
It sounds like Ryan's experience was between ours in that that pad was insulating enough, but than when he rolled he found there were cold spots. If he didn't roll, or if he was laying on the pad more evenly it sounds like there won't have been a cold spot.
As Rick has pointed out… you can layer a foam pad over an insulated air mattress (or even an uninsulated air mattress) to add warm.
A question for Ryan… how quickly after rolling over did the cold spot warmed up enough and your weren't noticing it anymore?
–markFeb 14, 2007 at 11:20 am #1378476
It's hard to say, I was in and out of some pretty hard sleeping. I would pretty much just deal with it and try to go back to sleep. I'd say it would warm up after me falling back to sleep because I remember feeling the cold spots until I fell asleep, then I'd wake up and shift and feel them again.Feb 14, 2007 at 1:13 pm #1378498
I'd have to say that I'm somewhere in between with my POE Max Thermo. I'm not really comfortable below mid-30's. In the other thread Mark started about sleeping pad warmth/weight ratios (http://www.backpackinglight.com/cgi-bin/backpackinglight/xdpy/forum_thread/6336/index.html), he has the Big Agnes Air Core (comparable to the Max Thermo) at a higher R value than 1 inch self-inflaters like the Prolite, but I'm much warmer on the self inflaters (I use a POE Max Lite 1.0 3/4 length, discontinued) than on my Max Thermo. To confuse me more, I consider myself a warm sleeper!
Anyway Ryan, if you supplement your Max Thermo with a closed cell foam pad (and you probably won't need much, I use a torso length 1/2 thick piece similar to the Z-Rest), use it on top, where you'll get the insulating benefits of the CCF pad next to your body. These pads work by trapping your body heat in the pad. If you put it under the inflatable mat, there's not much heat making it all the way through the POE pad to the CCF pad below and it won't help much. I've done this successfully in temps well down into the teens.Feb 14, 2007 at 1:49 pm #1378513
Joe ClementBPL Member
I had mine down to 18 degrees, and didn't notice any cold spots. But I was using my antique George L. Herter's Canadian Goose down sleeping bag that weighs about 10 pounds. I'd try it over a foam pad. I know that I can't sleep on anything but one of these air mattresses, now that my age has advanced. The 40s may be the new 30s, but not when it comes to sleeping on the ground. Or hangovers.Feb 14, 2007 at 3:18 pm #1378519
@chumangoLocale: East TN
I find the pad to be a little cool at 20. Last weekend at 19 F I felt cold spots every time I moved. And I was using a closed cell pad under it. I think that is because there was enough of the pad exposed to cold air (sides, and top where the bag was not resting – side sleeper) that the air in the pad still gets cold. I think the best thing to do would be to use the closed cell pad on top of the Insulmat.
I find the Insulmat Max Thermo to be a little warmer than the Big Agnes Insulated Air Core, but not by much.
I also think synthetic insulation is a little warmer with these air pads than down. My down bag compresses so much underneath me that there is very little insulation there, and I feel the effects of the air convection in the pad a little more.
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