Thermal Expansion Tanks Protect Your Hot Water Heater

At Advanced Plumbing & Drain, your Cleveland thermal expansion tank specialists, it’s our responsibility to make you aware of local and federal code requirements, and explain why they might be needed, so you can make an informed buying decision. For example, the Thermal Expansion Tank. It’s that barrel-looking thing located at the top of the water heater, usually located on the cold water supply line. They come in many different sizes, which differ based on water pressure, the amount of water that is heated, and the temperature the water is heated to.

Of all the options for an installation of a water heater, a highly debated topic is the necessity of a Cleveland thermal expansion tank. To us, the discussion is quite simple. An expansion tank should be installed with every water heater, every time, regardless if an expansion tank was previously used. It’s a simple matter of physics. Most people understand that when water is heated, it expands. So, if water is expanding, where does this “extra” water go? The expansion tank. When sized right and installed correctly, it’s the expansion tank’s job to take on this “extra” water caused by thermal expansion. Thermal expansion tanks have a rubber bladder in them with an “air cushion” on one side, while the other side is connected to the water piping.

When thermal expansion occurs, the water presses against the bladder and compresses the air cushion on the other side of the bladder to allow for that “extra” water to expand into the thermal expansion tank. When someone opens a faucet the compressed air presses on the bladder in the other direction to push the excess water back into the plumbing system. This device sized, tuned, and installed correctly minimizes excess pressure caused when water expands from being heated.
Okay, so that’s the “what”. Now here’s the “why”.

In the past, expansion tanks were not as necessary as they are today. Back then, when thermal expansion would occur it would push the expanding water back through the plumbing system and into the city main. Today’s plumbing systems are more sophisticated, utilizing controls and valves for efficiency and comfort. This often creates what is called a “closed system,” which prevents the expanding water from traveling back into the public water system. Many utilities have also been adding check valves to their water meters, so that once city water passes your meter it cannot flow back into the city supply. This makes your entire home a closed system. Since all of these things could potentially play a part in your plumbing system, the water is essentially trapped in this closed system until someone opens a valve.

Imagine what happens when the water is heated in this closed system. With nowhere to go the pressure begins to increase substantially as the water tries to expand. This pressure could go well above normal working pressure, and could exceed 150-psi (pounds per square inch) if it weren’t for the safety relief valve. This valve is designed to open and relieve pressure from the water heater when it goes above 150-psi, draining to the floor, then outside the building where it won’t cause water damage. A system without a working expansion tank can face potentially large swings in water pressure, taxing the glass lining of the water heater, and other plumbing fixtures and components throughout the whole building.
A good installation will help maintain minimal pressure increase caused by thermal expansion, can reduce water hammer, and help protect plumbing components from strain. An incorrect installation can be as bad as having no expansion tank at all, and sometimes worse. Incorrect installation can be the cause of everything from high water bills and water hammer, to excessive wear on the water heater and plumbing fixtures. Thanks for reading about Cleveland thermal expansion tanks!