Most homes are now equipped with check valves at the water meter that prevents water going to your house to be fed downstream back into the domestic water supply. This has created a closed loop system on your pluming system. Code now requires the plumber to install an expansion tank as extra safety on closed loop plumbing systems. Not only is it safer for you and your family, it will make your plumbing fixtures and water heater last longer.
Make sure you have a thermal expansion tank installed near your water heater. Thermal expansion helps absorb the pressure rise in a closed loop system. When the water heater temperature rises, the pressure increases. This is called thermal expansion.
A quick way to see if you have thermal expansion, consider opening the faucet in the morning before anyone else has used it. Does the faucet seem to burst water at you at first? This is called thermal expansion.
If you are looking for an alternative to an expansion tank, you can install an expansion valve. When installing an expansion valve there has to be a connection to the hot water supply. The valve has a 1/2" drain and needs to be piped to the exterior.
