Thermal Expansion Tanks
What is Thermal Expansion?
How would the pressure increase affect my household plumbing if I didn't have a Thermal Expansion Tank? Before you can understand how it will affect your plumbing, you need to know how the plumbing in your house connects to the water main in the street. Water is delivered to your house through a service line. Before the service line enters your house it passes through a meter pit, which is usually located in your front yard. The inside of the meter pit contains a small check valve that prevents water from moving from your house back into the water main. Such an occurrence might happen if the main were to break, causing a local depressurization of the distribution system. The check valve prevents any possible contaminates from entering the main where they might affect other users on your system.
Water volume increases when it is heated, such as with your hot water tank. A typical residential hot water tank holding 40 gallons will increase by about a half a gallon when heated 70 Fahrenheit degrees. But if the water has no room to expand then pressure will begin to increase resulting in damage to your hot water tank or plumbing. However, if you do not have a check valve in the meter pit then your plumbing is unrestrained. The volume expanse brought about by your hot water tank will simply expand back through the meter and into the water main, and because it is unrestrained their will be no increase of pressure.
For homes that do have a check valve, the potential for causing damage to your plumbing system is much greater, but you may still go several years without experiencing any problems. Here are several reasons why:
•The increasing pressure might cause a small leak at a fixture, such as a toilet or faucet, causing it to run or drip until the pressure is relieved.
•If you stop using water before the hot water heater is done running the pressure may still increase, but not by enough to be noticed.
How important is a Thermal Expansion Tank?
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