From ThermaCELL page. I did not know either
My ThermaCELL Mosquito Repellent is not working correctly at higher elevations.
Unfortunately, Thermacell repellents will not work well at higher elevations. We find that units become difficult to start and run at altitudes above 4,500 ft. (above sea level). The lower air density causes the problem. If you are having trouble using your Thermacell above this elevation it is probably not a defective appliance it is just a limitation of our product at high elevations.
If you are not happy with this limitation and have no use for your Thermacell at lower elevations we will refund your purchase price. We want our customers to be completely satisfied with their Thermacell purchases. Please e-mail us at
[email protected] or call us toll-free at 1-866-753-3837 if you would like to return your Thermacell or if you have any questions.