I made a dive this morning and tried something weird. It worked. So I tried it again an hour ago on a night dive, and it really does work. What I did was to take one of those chemical hand warmers (you know, the ones that get hot when air hits them) and stick a small piece of double-back tape to the top of it and stick it on my chest under my dry suit right where the inflator valve blows in. And sure enough, every time I gave the inflator a burst, it blew nice warm, toasty air on my chest! VERY noticeable. Water temp was 47 degrees. But even 50 mins. into the dive the warmer was still doing its job and warming every blast of air. Very nice.