BA Insulated Air Core and cold weather

[NC Blaster]

I'm heading out this weekend and the overnight temps will be @15F. I have a Big Agnes insulated Air Core pad (R value of 4.1) and I was going to use it in conjunction with a ridge rest. Will this be sufficient underneath insulation? If so, which do I put on top? I have heard many arguments about which way to go but I was hoping somebody has the same gear. I have a Marmot Lithium bag so I'm not concerned in that department. Thanks for the help.

[DeerPath]

I tried my BA Air Core on top my Thermarest Z-Lite and it slid around. I think a velcro strip at top and bottom would help.
Happy Trails

[colorado_rob]

I've found that for deep-cold, winter camping, anything over about R5 has diminishing returns, meaning any more weight is better spent on insulation above, so your combo sounds great to me. I typically use an R3 inflatable (new neo air) with a ridge-rest in combination, making total of close to R5, and I've done some seriously cold stuff this way (-25F a couple times). Some folks say lay the ridge rest on top of the inflatable, but I do the opposite, ridge rest on the bottom. Probably doesn't make too much difference.

[NC Blaster]

Yeah, I was thinking of putting the inflatable on top since it has a higher R rating.

[colorado_rob]

R values add directly, so shouldn't matter. However, second order effect, the great the temperature difference across the inflatable, the more internal convection that would occur, lowering it's effective R value a bit. The Ridge rest, being closed cell, should not have any convection currents. So, I'd put the inflatable ion top to minimize it's internal convection, thereby slightly raising its R value. the net effect should be small though. Forgive the nerd (ex) engineer.

[slbirdnerd]

I have the BA Insulated Q Core and a Z-rest, which I will also be using this weekend with an expected low of around 15. If you weren't in NC I'd ask if you're going on my hike! :) I tried this in my garage one day a few weeks ago. Granted it was not as cold as it will be Saturday night, but if was comfy and cozy. I had the Zrest on the bottom.

[NC Blaster]

Numbers don't lie.

[Tom Murphy]

R values add directly, so shouldn't matter. However, second order effect, the great the temperature difference across the inflatable, the more internal convection that would occur, lowering it's effective R value a bit. The Ridge rest, being closed cell, should not have any convection currents. So, I'd put the inflatable ion top to minimize it's internal convection, thereby slightly raising its R value. the net effect should be small though. Forgive the nerd (ex) engineer.

I find the CCF pad on top works better. I belive this set-up [CCF on top] does a better good of limiting the the temperature difference across the inflatable. So I agree with your theory but not your conclusions.

The baffling in NEOAIR pads limit the internal convection.

[NC Blaster]

oops. I meant to quote Colorado Rob

[misterfloyd]

Used my new insulated Aircore a couple weekends back in 11 degrees by itself. It did fine.

I had the Original one, the one with the brass valve replaced by BA a few months back after going to Mt. Mitchell for a few days. The brass valve went wonky. They replaced it with the new and improved one with the plastic valve. Not crazy about brass vs plastic, but gots to give it to BA's service.

Have a great trip, By the way, I live in NC as well..........

Floyd

[colorado_rob]

I find the CCF pad on top works better. I belive this set-up [CCF on top] does a better good of limiting the the temperature difference across the inflatable. So I agree with your theory but not your conclusions.

The baffling in NEOAIR pads limit the internal convection. Yep, the baffling helps, but doesn't eliminate convection, it's doing just what down does in sleeping bags. Hence why I said this was a second order effect.

Upon further reflection, I think we're both wrong and that it makes no difference whatsoever (from a heat transfer standpoint) how they are stacked, as the only thing that matters is the delta-temperature across the pads, not what temperature state either pad is in, if you follow. I think the total delta-T across either pad is identical (ignoring tertiary effects) in both cases. HOWEVER, I only took two thermo/heat transfer courses and both of those were 35+ years ago, so what do I know.

[NC Blaster]

I think the difference is that you feel immediate heat reflection from a CCF on top but the inflatable takes a little time to warm up. I will try the inflatable on top because it will be more comfortable. If I get cold, I'll switch.

[magic_game03]

Man I remember my first thru-hike… 30deg. coleman synthetic and a ridgerest starting in early Feb….COLD!!! Anybody on a BA Air Core and has a Marmot Lithium should be smiling. I'll be out this weekend (1/18 - 1/21) in the Smokies or Doah's (haven't decided) with the same setup: 0deg. bag, Neo-Air, and a 1/2 Ridgerest.

P.S. Just remember to make a hot nalgene for the sack every night at bedtime and you'll be fine.

[TNhiker]

Used my new insulated Aircore a couple weekends back in 11 degrees by itself. It did fine.

I had the Original one, the one with the brass valve replaced by BA a few months back after going to Mt. Mitchell for a few days. The brass valve went wonky. They replaced it with the new and improved one with the plastic valve. Not crazy about brass vs plastic, but gots to give it to BA's service.

Have a great trip, By the way, I live in NC as well..........

Floyd



ive sent back to big Agnes two of their insulated pads due to the valve leaking...

Theyve been nice enough to replace them both times.....

[NC Blaster]

One more vote for the CCF on top of the inflatable. I gave the inflatable about 30 minutes to warm up and it never did. I switched and put the CCF on top and the difference was immediately noticeable. Thank you magic_game03 for the hot Nalgene suggestion. I will be doing that on cold hikes from now on!