Sharpie, I'm thinking about buying some of these for my wife to warm her shoes in the morning. I appreciate they're not great for drying but, in your opinion, do they work well as warmers? Or would she need to have them plugged in for a few hours to feel the benefit? Thanks!
Dear mrjimsmith, since we have not been properly introduced (see
New Members Please Post an Introduction) I couldn't possibly comment on your wife's need for drying out, warming nor plugging in to feel the benefit. Perhaps you should address your concern to Mrs Mills at The Times.
Failing that, I can assure you that the boot warmers are not much use for comfort, but quite useful for gentle drying overnight, using very little electricity. They are rated at 8 watts (total i.e. 4 watts per boot) and maximum 55 Celcius. I think they use PTC thermistors so are self regulating.
FYI I have made the following measurements warming my heavy Scarpa 4 season mountaineering boots using an infrared thermometer:
Start temp. ambient 15 c (I don't heat my hall)
15 minutes, exterior boot toe, 20c, interior 25.
1 hour exterior 23 interior 30.
Several hours, exterior 25 interior 33.
So the "warmers" manage to raise the internal temperature by 18 degrees above ambient. This is good for very slowly drying leather boots, ideal for modern ones with a goretex membrane that needs a temperature differential to drive moisture vapour out.
To warm your wife's shoes a little bit they would have to be left on for several hours/overnight. Would use negligible electricity at only 8 watts max.
As I said, they are fine for overnight airing of gently used boots, but if you want efficient rapid airing/drying of damp or soaked boots then one of the blown-air devices works so much better.