New Virginia Law On Expansion Tanks!

We have been getting a lot of questions about expansion tanks recently. What is an expansion tank? Why do I need them? Are the required? New Virginia Plumbing code states that all gas water heaters installed in a closed system (there is a back flow device near) are required to be accompanied by an expansion tank. Here are some helpful tips and information on water heater expansion tanks.

An expansion tank is a device that is installed near a boiler or water heater system. It is designed to relieve pressure caused from the thermal expansion of hot water. It works by using an expanding diaphragm that is activated during thermal expansion. The top part of the tank is hot water, and the bottom part is air. If an expansion tank goes bad - or the diaphragm fails, you can tell because the whole tank will be filled with hot water. Just tap on the top and bottom of the tank. It should make a hollow sound on the bottom (which indicates that it is empty) and a thud like sound at the top.

The reason expansion tanks are being required is because of new requirements on regulator valves and backflow devices as well as the certain counties increasing water pressure. Before backflow devices were required, the expansion caused from the hot water could easily flow back through the pipes. Now, because of the backflow prevention devices that are necessary, the water has no where to go and could potentially ruin household plumbing fixtures as well as the water heater itself. An expansion tank relieves the pressure from the expanding hot water which will prevent a lot of damage.

A good thing to note as a home owner is that some water heater manufacturers will actually void the warranty on their product if no expansion tank is installed with their water heaters. It is always best to read the manufacturer's manual as well as check with your county's officials regarding any requirements for the safety of your home.