Installing a thermal expansion tank with a new water heater has become increasingly important. Most cities nowadays have check valves in their water meters which prevent the home’s water from going back into the public water system. While this process poses a health benefit, it creates a problem for the domestic water system.
The check valves make the domestic water system in a house a “closed system.” This means that when the water in the water heater is heated, it expands but has nowhere to go. It therefore increases the pressure in the domestic water system, potentially causing damage and leaks to the system. See attached brochure from Bradford White for more details.
There exists a simple solution: to install a thermal expansion tank on the cold water inlet of the water heater. Sizing is also simple: use a HWTX5 tank for 40 & 50 gallon water heaters. For water heaters above 50 gallons, use a HWTX12 tank. Expansion tanks are cost-effective and easy to install with a new water heater.