tinymoose
Ski Diva Extraordinaire
Also toe warmers need enough air to function. In my previous boots the fit was such that they were not getting enough air. They would never really warm up and be cool when I removed my foot but would immediately start warming up after I removed the boots. I found that if I let them warm up for 5-10 minutes before inserting my foot into the boots they worked much better. With the limited air they would start cooling off after about 2-3 hours but could be revived at lunch time.
Of course if they are getting too much air they will initially get quite warm then burnout too quickly.
One way I've gotten around this in boots where there just isn't room for a toe warmer, is to put a hand warmer on top of the outside of my boot and then cover it in a boot glove. Boot glove holds it in place, and amazingly some heat from the hand warmer seeps into the boot through the plastic.