What is a water heater expansion tank?
A water heater expansion tank, also known as a thermal expansion tank, is a small overflow tank that compensates for the thermal expansion of water inside a water heater. As the temperature of water increases, the water expands. Without relief, the pressure inside the water heater will increase, causing damage to valves, plumbing, or the water heater itself. Prior to the requirement of check valves, excess pressure would force water back into the municipal water lines. Regulations on backflow have necessitated the use of check valves or other similar devices to prevent contamination of the public water supply, but they have also placed greater stress on water heaters. Thermal expansion tanks solve this problem by accommodating overflow water that results from this added pressure.
Do I need a thermal expansion tank for my water heater?
Expansion tanks are required by code in all new water heater installations in closed systems. A closed water system uses check valves, back flow prevention devices, pressure-reducing valves, or other devices on the supply line to prevent water from being sucked back into the municipal water supply. In 1992, the EPA required municipal water suppliers to protect their lines from back flow contamination. This means homes must incorporate check valves to prevent water from backing up into the supply lines. As a result, these homes are closed-loop systems, so all new water heater installations must incorporate a thermal expansion tank alongside the water heater.
If your current water heater is not equipped with an expansion tank, the addition of a water heater expansion tank can benefit your system. High pressure in a water heater can lead to problems such as leaks, ruptures, and corrosion within your system, all of which can be expensive to fix. While a water heater expansion tank is an added cost, it can save you money in the long run by preventing these problems.
Advantages of water heater expansion tanks
Water heater expansion tanks are so beneficial to your home’s plumbing system that they are now required by code. Thermal expansion tanks provide the following advantages to your water heater system.
- Prevent leaks caused by pressure buildup
- Provide a second layer of security alongside the water heater’s pressure relief valve
- Save money caused by water damage or pipe bursts
- Inexpensive to purchase and install
- Take up little space
This is Smedley Plumbing in Kansas city, MO. He gives the best explanation on YouTube of what an expansion tank does, and why you may need one.
