PTC water heater, shower water heater. The power can be adjusted itself. When the water is dried, it's no trouble.  

Notice for manufacturer and consumer:

PTC as heating element, it fits for high safety, slap-up product. Using to maintain temperature of water is very excellent and also low cost.

For getting higher power, let water flowing or convection, ensure compact assembling, and using high heat-conducting materials such as copper or aluminum. The power density is about 6W /cm2at 25 waterfor immerging heater or transflux heater. The higher temperature is the water, the lower is the power.

Using higher switch temperature PTC can get higher power, 220~270switch temperature PTC is selected usually. But if select too high switch temperature, the reliable will reduce.

2.                     Classify by structure for PTC heating

Type	Specialty	Excellence	shortcoming	Others
Transflux heater	Water transflux  hole of the heater	Large power, quick heating	Water must flow	It can be used to heat tap water supply
Immerging heater	Heater immerge at bottom of water tank	It can be used to heat quiet water	It is long time to heat the water in whole tank	Used to maintain temperature of water
Bottom heater	Heater put under bottom of water tank	It can be used to heat quiet water	It is long time to heat the water in whole tank	Used to maintain temperature of water

Water heating tube