Heating packs

[coldspace]

I think because these are sold in astronomy shops they could be considered as an aid to observing so I put this question in the equipment area but mod's move it if I am wrong.

Has any one used or recommend those heating packs that heat up and can then be boiled the next day for reuse? do they work very good? How long do they keep pumping out the heat? Are they worth getting for winter or more of a gimmick type thing?

I am thinking of getting some to keep my wife happy and warm in the caravan through winter why I am out observing. I will look at getting them as well if they work. Opinions anyone.

Matt.

[drmorbius]

I bought some small ones a couple of years ago and keep them in my pocket to warm up my fingers on cold night. They can get quite warm and last for over an hour. The bigger ones may last longer?

I've reboiled them dozens of times (the kids love to trigger them off :rolleyes:) and they just keep going. They cost me $10 each and it was worth it.

[Karlsson]

We have been using them for years for this purpose - not in a caravan, but in and around a tent, all year round. My wife will not leave home without them - we keep about 8 of them in rotation :)

[[1ponders]]

They are fantastic. My wife was a massage therapist and she used to sell them. Thanks for reminding me, I'm sitting out here innnnn thhheee frrreeezzing cccold and I have a couple of packs in the closet. :D Back soon :lol:

[beren]

I brought two off Paul last year :) they work great, pump out the heat and last a fair while too, the ones I have are large and can be worn around the waist. When I can get them off my wife they are lifesaver during the colder evenings.

[Gargoyle_Steve]

I have a few in various sizes and I find them useful and beneficial, they do have limitations however:

1/ In my opinion the heat just doesn't last long enough. They are great while pumping it out, but the amount of heat given out declines fairly quickly after the first 20-30 minutes. You almost need to own several to get you through sometimes (I'm working on it, still building my collection)

(I have however used a small (pocket) one that was past it's main heat output and put it in a sealed box with my ep's to keep them warm, after my hands have sucked the big heat out of them - worked a treat!)

2/ They take a LOT more energy (ie boiling) to drive the chemical reaction back the other way and "Set" them again, and as a result I did have one melt and lose it's essence in the pot once while boiling it up yet again - my fault though, a small one got trapped under 2 large ones, it was held against the hot metal on the bottom of the saucepan and melted like cheese on an over-nuked cheeseburger.

And yet I continue to use them and love them - a larger one inside my observing gear, held against my kidneys on really cold nights, hand warmer size in the pocket, etc. Great stuff!

[coldspace]

Thanks for the feed back everyone, I went out and got 4 large ones today and they do heat up fast. Should keep my wife happy now ;) for this cold long-weekend coming up, hopefully some clear dark skies.

Matt.