I have used the hot packs like at the PT's use. I soak them in hot water in the cleaned sink for about 5 minutes then microwave for 4 minutes. Then wrap in towels.
They work great but a pain in the butt. Need to hang dry so they retain shape.
About 1993 I got a Thermophor moister generating heating pad. Plug it in and use it. It gennerates it's own mild moisture. No water needed. It works great!!! And I still have it and still works!!! It is a little expensive. But look at how long I have had it!!!
I have a box of about 5 other heating pads that all sucked.
I have a deep tissue full body heating pad from Hammacher Schlemmer and it's awesome! It has infrared technology to get deep into the tissue. It was a holiday gift - I requested a heating pad. It's a little pricey but I can't imagine any other one now that I have it!