1.what is the diffierent of nonr-pressure tank and high-pressure tank?

2.What is the diffierent of Stainless Steel and Porecalin Enamel Tank?

3.How number meterial of Stainless Steel? and what different of they price?

4.What is the Heat Exchanger?

5.Do you need Heat Exchanger?

6.How to check the tank safety?