Forum Index » GEAR » Using hot water bottles as 'cached heat'


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(Ice-axe)
@ Jake on 12/20/2012 07:35:46 MST Print View

Hot water in a soda bottle is the primary reason to carry a stove at all in snow country for some of us.
Otherwise we follow a no-cook strategy.
As a side note, instant mashed potatos hold heat even better than water though you would want to have them in a ziplock container rather than your bottle.
Gatorade and aquafina type bottles work fine as hot water bottles but just make sure it's HOT water and not ridiculously "hot to the point of melting the plastic" water.
In practice it is pretty simple to have your stove set up just outside your shelter and ready to go for a quick liter of hot water in the middle of a cold night.
As for fuel weight; if the intention is only to make hot, and not boiling, water you will find that a fraction of an ounce of alcohol or of an esbit tablet will do the trick.
I know there are those folks out there that say they have melted soda bottles using this technique.. Well, don't use boiling water.. Just hot water right?
As previously stated, this is probably best used as a suplement to comfort rather than a replacement for true insulation value.

michael levi
(M.L) - F

Locale: W-Never Eat Soggy (W)affles
Re on 12/20/2012 08:14:49 MST Print View

Hot rock works well for me the few times I needed it. Having a sleep system that is accurately rated is the best solution though.

Gregory Stein
(tauneutrino) - F

Locale: Upper Galilee
Re: @ Jake on 12/20/2012 09:08:39 MST Print View

IMHO:
Nothing holds heat better than water. No matter what you add to it, plain water holds warmth best of all other materials. Heat capacity of water is 1. This is what I remember from school physics...

Franco Darioli
(Franco) - M

Locale: Melbourne
Using hot water bottles as 'cached heat on 12/20/2012 14:13:05 MST Print View

Gatorade and aquafina type bottles work fine as hot water bottles but just make sure it's HOT water and not ridiculously "hot to the point of melting the plastic" water.
In practice it is pretty simple to have your stove set up just outside your shelter and ready to go for a quick liter of hot water in the middle of a cold night.


No and no
Gatorade and Aquafina bottles do not make even remotely a good hot water bottle and for the reason you mentioned : you can't put boiling water in them.
If you start with hot and not boiling water even inside a "cozy" after 4 hours or so at 40f you will have warm (at best) water not enough to make any difference inside a sleeping bag. Below freezing you will have cold water in an hour or so....
As for heating up water in the middle of the night, well it might be simple in mild weather but it isn't in below freezing weather particularly on snow.
The heat you (and your bag) lose by getting out of your bag and spending the time to start the stove, boil, put that in to the water bottle and go back to bed will be more than what you gain from having that liter of hot water.
Please do keep in mind that bad advice for winter camping can kill.

David Olsen
(oware)

Locale: Steptoe Butte
1 quart nalgene on 12/20/2012 15:01:39 MST Print View

I have found I get 6 hours of warmth from a 1 quart nalgene bottle full of boiling water stuffed in a wool sock. This I have
done for weeks at a time. I also keep my stove at the head of my bed so if I need more for one of those 14 hour nights, I can
reach out and start the stove out from under my tarp and stay in my bag while the water heats. I use a whisperlight stove and
carry extra fuel just for hot drinks and hot water bottles. On really cold trips I also bring 1 pint bottles and use them in the
morning in my double boots to prewarm them and then tuck the still warm bottles in my parka pockets or the small of my back
till camp is broken down.

Of course you must keep your stove far away from any fabric,

Be careful of spilled fuel as hazard of fire or contact frostbite.

CO is a danger in an enclosed shelter.

David Olsen
(oware)

Locale: Steptoe Butte
hand warmers on 12/20/2012 15:07:10 MST Print View

There is no comparison using hand warmers vs a quart of boiling water. The hot water bottle will help drive out moisture from
your sleeping bag and clothes too, hence you will be warmer in the long run and your insulation will be more efficient.

Try them and see.

Gary Dunckel
(Zia-Grill-Guy) - MLife

Locale: Boulder
Body warmers on 12/20/2012 16:28:47 MST Print View

I don't know, David. Grabber Mycoal's body warmers put out an impressive amount of heat for nearly 12 hours. Not bad for 1.2 oz. each.

Jim Colten
(jcolten) - M

Locale: MN
Re: 1 quart nalgene on 12/20/2012 16:39:17 MST Print View

On really cold trips I also bring 1 pint bottles and use them in the
morning in my double boots to prewarm them and then tuck the still warm bottles in my parka pockets or the small of my back
till camp is broken down.


I'll have to give that idea a try! Putting feet into cold footwear is one of my least favorite things. They eventually warm up but takes forever when very cold. Bonus ... it leaves you with a liter "not yet cold" water to drink while you are moving.

Edited by jcolten on 12/20/2012 16:40:11 MST.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Use of chemicals is an acceptable option? on 12/21/2012 00:39:32 MST Print View

You can get the reusable sodium acetate phase change hand warmers, and they are pretty reliable. They are not terribly hot, though. Being recharged in boiling water makes them good.

--B.G.--

Justin Baker
(justin_baker) - F

Locale: Santa Rosa, CA
Re: Using hot water bottles as 'cached heat' on 10/16/2013 22:28:32 MDT Print View

On a recent trip, a guy I was with used a stainless steel water bottle and put a wool sock over it. He said it lasted all night.
There must be something to stainless.

just Justin Whitson
(ArcturusBear)
Re: Re: Using hot water bottles as 'cached heat' on 10/16/2013 23:01:11 MDT Print View

Nah, it's fairly conductive, though not near as bad as aluminum. Most thicker type plastics used for water bottles are significantly less conductive than stainless steel.

A simple way to test this, is to fill up a stainless steel bottle with boiling water, feel it after a little while and do the same with a thicker plastic water bottle.

The stainless steel bottle will feel much hotter to the touch than most of the thicker plastic ones, and that's because it's conducting the heat out more efficiently.

If the wool sock helps the stainless, it will definitely help a thicker plastic bottle.

Edited by ArcturusBear on 10/16/2013 23:02:31 MDT.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Re: Re: Using hot water bottles as 'cached heat' on 10/17/2013 08:00:06 MDT Print View

It seems like the bottle would mostly cool down by morning

My body gets gradually cooler by morning - my metabolism slows down, the outside temperature gets gradually colder

The problem is that if I get cold, can't sleep, so I just get up

It's better when I have sufficient warmth so I stay in bed until the sun comes out and starts warming up

It seems like the hot water bottle doesn't help much for this situation, so it's not a very useful technique

If someone, like, had hypothermia and needed to warm up it would be good

David Olsen
(oware)

Locale: Steptoe Butte
Beauty of tarps on 10/17/2013 10:16:55 MDT Print View

Jerry-

Keep your stove handy just out from under the tarp. After the first bottle goes cold (usually 6 hours for a quart in a wool sock in my bag) I pour it back in the pan and boil it again, all from the comfort of my sleeping bag. Then there is enough heat for more sleep and you can keep it inside your parka upon arising and breaking camp. Feels good on stiff back muscles. Recently I have been using the Gatoraid bottles for this. I replace the bottle each trip.

Justin Baker
(justin_baker) - F

Locale: Santa Rosa, CA
Re: Beauty of tarps on 10/17/2013 11:31:39 MDT Print View

It helps if you use a wood stove so you aren't using a ton of fuel on hot water bottles.

Justin Baker
(justin_baker) - F

Locale: Santa Rosa, CA
Re: Re: Beauty of tarps on 10/17/2013 11:36:10 MDT Print View

My main hiking buddy uses a 3 liter nalgene bladder. He will sit there heating up the water by the fire and filling it. It's incredibly warm.
In the middle of the night he will wake up, restart the fire, and refill the bag with hot water.

btw, Justin you are like the new bob gross.

Edited by justin_baker on 10/17/2013 11:41:37 MDT.

Richard Fischel
(RICKO) - F
"It seems like the bottle would mostly cool down by morning" on 10/17/2013 12:42:08 MDT Print View

i'm not too concerned about the bottle cooling by morning. my thinking is to the extent that i'm not wasting personal calories to warm me and my sleeping bag because i'm using hot water bottles is a big plus. the hot water bottles warm my sleeping bag faster than i could and give me a reserve of calories to burn later in the night. one of the problems of cold weather camping is eating enough calories to begin with so if i can save some that's great. i'm also a fan of eating something(three musketeers/snickers) and brewing up a hot beverage right before i go to sleep for some extra fuel for the furnace. as an additional plus, the water that's cooled overnight gives me a head start on the water i will need the next day.

just Justin Whitson
(ArcturusBear)
Re: Re: Re: Beauty of tarps on 10/17/2013 12:43:13 MDT Print View

Maybe in 30 more years and with A LOT more experience I will be Bob Gross? Also i probably got a much stronger "mystical"/spiritual side, well who knows. Maybe future Bob learned how to time travel and took one of his past young selves from an earlier time (me) and injected them into a latter time frame...? Hopefully it won't create any irreversible damage to the fabric of time-space. That would kind of suck. Bob, we should know better!

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: "It seems like the bottle would mostly cool down by morning" on 10/17/2013 14:10:53 MDT Print View

"not wasting personal calories to warm me and my sleeping bag..."

A lot of people are happy with this so I just let it go, but

when you go to bed, your metabolism is higher so you quickly warm up your sleeping bag

the problem is at the end of the night when your metabolism has slowed down

I suppose if you went to bed really cold, it would tap into your reserves to warm up so you'de have less at the end of the night. Or if you were treating someone with hypothermia, then definitely warm bottles would be good.

But in normal conditions, if your sleeping system isn't quite warm enough for conditions, warm bottle won't make much difference

I normally go to bed a bit warm and leave sleeping bag open a bit and close up when I start to get cold. If I had a warm bottle, I'de just delay closing up a little.

Richard Fischel
(RICKO) - F
"I normally go to bed a bit warm and leave sleeping bag open a bit and close up when I start to get cold." on 10/17/2013 15:27:46 MDT Print View

we are talking about different situations. if i'm planning on using hot water bottles it’s because my sleeping bag is cold when i get in and i plan on zipping it up tight, pulling the neck closed and reducing the size of the face opening to the point that all you see is my mouth and nose. i'm not letting any hard earned heat escape once i get in and with any luck, i'm not getting out until it is time to get up. i find that i can fall asleep much faster if i’m warm, and i can get the inside of my sleeping bag warmer faster with the use of hot water bottles. once i’m asleep i can stay asleep even if i cool off some by the morning. a hot water bottle at your feet and one between your thighs is just a glorious way to fall asleep especially when it’s single digits f or below. if i have the luxury of lounging with my sleeping bag open because i’m too warm before i go to sleep i’m not using hot water bottles either.