... heat exchange 2.energy saving, noiseless,not dry 3.far infrared, 4.more healthy 5.comfortable 1.Application area: carbon crystal ... ect.They are popular in winter and places requiring constant temperature. 2.Work Theory (1). Carbon crystal is the main ... years warrant(3).with automatical thermostat, temperature limited(4).no pollution, noiseless,not dry(5).far infrared, more healthy and comfortable(6 ...