What is water heater thermal expansion and do I need to worry about it?
Thermal expansion refers to the expansion in volume that happens when water is heated. What this means for your water heater is that every time a tank full of water is heated the water may require more space than is available in the tank. The extra water volume creates excess pressure in the plumbing system. This extra pressure can cause damage to the water heater, fixtures, and water piping over time.
So what happens if the pressure is not relieved? . . . Hot water tanks contain a pressure relief valve to protect them from rupturing under such a scenario. The valve opens when the tank pressure reaches the valve set point. After enough water has passed through the valve the pressure in the tank drops and the valve closes again. Sometimes in older hot water tanks the valves might be plugged with scale or corrosion and not function properly. For this reason, a thermal expansion tank is recommended.
A water heater expansion tank is designed to help prevent fluctuations in water pressure. The water heater expansion tank serves as an overflow receptacle by absorbing excess water volume that the water heater creates when heating water. . It is important to note that even with a properly selected and installed thermal expansion tank the plumbing pressure will still increase, but not by enough to cause a failure in the plumbing system.
Le-Ax Water District
P.O. Box 97
The Plains, Ohio 45780
Phone: (740) 594-0123
8:00 am to 4:00 pm
Monday through Friday
After Business Hours
Phone: (740) 593-7502