I'm replacing my 20 year old water heater. The instructions for the new one suggest that I might need a pressure regulator and expansion tank. The old heater worked for about 20 years without either. Do I really need either one?
If your on a municipal water system with a check valve on your supply line you may need an expansion tank, but if you have a well with a pump you probably already have a pressure tank. When a water heater is filled with cold water and heated it expands, the extra water has to have someplace to go. Also if you're on a municipal system the pressure may be too high, it's not recommended to go much over 70 psi, then you should install a regulator.