Many people call and say their Biomat stopped heating up. This was mainly before the Quantum Pad came out that doesn't block the heat from coming through. Many people also use heavy wool blankets to cover the hard amethyst rocks so they can sleep all night on the mat. The mat goes to 158 degrees but when the heat is blocked, the Biomat can heat up. It is protected so it shouldn't burn up but the heating element can get ruined.
WARNING - BUYER BEWARE:
If you want to protect your Biomat I strongly urge people to only use natural fiber blankets and sheets and especially a pillow that won't overheat the mat. So many pillows damage the Biomat as they overheat the clear covering where you can see the amethyst. That window can deteriorate if overheated. Man people keep the Biomat on its highest setting for 2 to 4 hours and don't turn it off even if a pillow is on it. I have never heard of any Biomat catching on fire but only heating elements and the urethane windows ruined.
Many people put layers of towels on the mat on high settings so the sweat doesn't go through the cotton cloth and soak into the Biomat. The waterproof pad that Richway makes also doesn't cause the Biomat to overheat like most synthetic waterproof pads.
If you are interested in using your Biomat at high settings, taking precautions to keep the mat from overheating should allow your Biomat to last many more years. Also, if the heating element was damaged by overheating, this is not covered by the warranty.