Expansion Tanks

NOW Required by Sacramento Plumbing code, to be installed at all water heater, Code Refrance: 2013 CPC Section 608.3 and 2013 CMC Section 1005.0.

What is an expansion tank & why do I need one?

An expansion tank is a cylinder tank about 2.2 gallons in size, and is typically now required for use on all water heaters from up to 50 gallons, larger expansion tanks for larger water heaters. They are also used for the installation of tankless water heaters.
Expansion tanks are built with a rubber bag (bladder) inside the tank and is about half the size of the tank it self, this bag is filled with air pressure that should match the pressure of the incoming water into your home’s main water supply piping from a municiple water source or a private well.

An expansion tank is required if a plumbing system is “closed”, which means that the back-flow that normally runs between the house and the main water supply is now blocked at the meter by a check valve, this check valve allows water to flow from the water meter to your home but, not backwards… blocking the extra pressure from thermal expansion of your water heater.
When water is heated, it starts to expand up to an average of 20% which causes a rise in water pressure, this increased pressure must go somewhere. If there is nowhere for the pressure to go, it places extra stress and strain on your water heater and your home’s plumbing system. Increased pressure will shorten the life of your water heater. However, expansion tanks provide relief from this excess water pressure and protect your home.


Whats inside the expansion tank


Actual Installation

Many homes have what is called a closed water system, which is a water system with a one-way valve such as a back-flow valve or check valve or pressure reducing valve, some of the newer water meters being installed have this valve built in and thus require an expansion tank installed since the excess water volume cannot be absorbed back through the city’s water system.
In a closed system this extra water pressure from thermal expansion can cause the most damage because the extra water pressure has nowhere to go since it cannot push back into the city water. Most cities now require that expansion tanks be installed in closed systems. If you have some form of backflow preventer installed on the main water line you may be required to also have a water heater expantion tank installed. Some cities may not require an expansion tank be installed such as the city of Elk Grove, CA does not require an expansion tank because they do not have check valves built into their water meters unless you have a hot water recirculation pump or and external back-flow device installed.

If you are going to replace your water heater, Water Heaters Pros will install this expansion tank on your cold water pipe above or adjacent to your 30-gallon, 40-gallon, or 50-gallon water heaters for only $169 as an upgrade, larger size water heaters require a larger expansion tank depending on actual size and cost more.

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