Water expands when heated creating a need for the extra water to flow out of the water heater. Before, it flowed back into the main water supply. Inventers created the check valve to prevent backflow, encouraging the water to go in one direction only. After the creation of the check valve and its installation in modern homes, it became necessary to install a water heater expansion tank.
Why Use an Expansion Tank?
The creation of the check valve led to the use of expansion tanks. Working together these two prevent backflow that could lead to contamination of the water supply. If water is reversed from a household water service supply line, the exposed water, often contaminated water is pushed out into the main water supply of the community. If your home lacks an expansion tank, but you notice water dripping from the relief valve of your water heater, you may need an expansion tank. As the water is heating, it will expand. If the water heater cannot absorb the expansion, water will drip from the relief valve.
Pressure inside the Water Expansion Tanks
Set the tank pressure high enough to lift the water to the highest level in your home, at least to the second or third floor bathroom or kitchen. PSI or pounds per square inch is a unit of pressure. Every pound of pressure lifts water 2.34 feet. A 12 PSI setting will raise water 28 feet, high enough to service a two-floor home. The plumber will need to decide if you can absorb the expansion of heated water. You’ll need at least 3% expansion capacity to go from 60-degree water temperature to 200 degrees Fahrenheit.
What’s in the Expansion Tank?
The expansion tank stands empty except for the partial filling of compressed air and an empty water bladder. As the hot water pressure builds up, the bladder fills with water. The compressed air absorbs the shock of the water surge or water hammer that results from the thermal expansion.
Expansion Tank Installation
Install the expansion tank near the water heater using mounting brackets. Install it vertically, horizontally or at any angle, and secured well. Always attach it to the water supply line near the water heater, the relief gauges, the pressure valve, the backflow preventer and the shut-off valve.
Cost of an Expansion Tank
The cost of the tank itself can be as little as $40 and as much as $200. The labor in your area might vary, but it ranges from $75 to $150. Homes that have excess water pressure building up in their water heater as it heats the water, should install an expansion tank. Its installation will cause their water pipes and faucets to last longer. These fixtures fare poorly when exposed to extreme pressure. When pipes and water faucets are exposed to too much pressure, the expansion tank will reduce that pressure. Essentially, adding an expansion tank will secure your initial investment. It will result in a longer life of the equipment installed in your home, saving you a lot of money over time.