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What is an Expansion Tank and Why Do I Need One?

Does your water heater need an expansion tank?

Chances are, the answer is yes. Yet, because expansion tanks were not as necessary in the past as they are today, you may not even know what an expansion tank is, let alone why you probably need one.

An expansion tank looks like a mini tank or boiler, and typically sits on top of, or adjacent to, the water heater. They come in many different sizes, depending on your water pressure, the size of the actual water heater, and the temperature the water is heated to.

water heater expansion tanks

As water is heated, it expands and its pressure in the tank vessel will increase if there’s no room for thermal expansion. The old domestic hot water heater plumbing systems were designed so that the expanding water in heaters would push some water back outside the house – into the public water main, which would absorb the pressure. But, with changes in city ordinances and plumbing practices, cities are no longer allowing hot water systems to relieve built up pressure back into the city water supply. This pressure build-up now has no place to go, which can cause major issues with your water heater including failure or bursting – and in some instances even explosion. An expansion tank is needed to prevent these issues.

Good news: The plumbing experts at ServiceMark can easily add an expansion tank to your existing system, alleviating pressure on your water heater and increasing peace of mind.

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Prevent Permanent Damage to Your Water Heater With an Expansion Tank

All water heaters, regardless of whether they use heating oil, natural gas or propane or even electricity, can suffer the negative effects of thermal expansion as the cold water coming into the tank turns to hot heated water, increasing the overall water volume via expansion and increasing pressure inside the tank. This increase in volume and pressure must be relieved for overall safety.

What Causes These Plumbing Issues?

Today’s plumbing systems, including your home’s hot water heater unit, utilize controls and other devices, such as check valves, (placed in the cold-water feed piping) for efficiency and comfort, often creating what is called a “closed system”. The purpose of these one-way valves is to prevent water from flowing backward out of the house through the supply piping, which prevents possible contamination from getting into the public water supply.

The inherent problem with check valves placed in the system is that the water pressure builds up in this closed system until someone opens a valve. Because of this, water heaters without expansion tanks run the risk of pressure building up, causing permanent damage to your water heater or even an explosion if the pressure gets too high.

If your water heater tank has a check valve or pressure-regulating valve, then you should immediately consider installing an expansion tank.

Where Does the Expansion Tank Come Into Play?

Here’s where the expansion tank comes into play: when both sized correctly and installed correctly, it absorbs this “extra” water into a bladder, located inside the expansion tank, and minimizes excess pressure in the water heater unit.

Expansion tanks help reduce water hammer and help protect the plumbing system from stress and damage, which leads to longer tank life. To do their job, these tanks must be properly located, sized, piped into the overall system and should be checked annually.

Our heating and cooling technicians will make sure each expansion tank is correctly installed, and maintained, to prevent water hammer, high water bills and unnecessary wear on the water heater and plumbing fixtures.

If you’re concerned that your water heater doesn’t have an expansion tank, ServiceMark can help.

ServiceMark Can Install Your Expansion Tank!

At ServiceMark, our fully trained team of exceptional heating, cooling and plumbing technicians and support staff are ready 24 hours a day, seven days a week to help make your home not only comfortable but safe as well! We offer same-day service and certified technicians who arrive on time, every time, guaranteed. Call the ServiceMark team to ensure your home is safe and comfortable all year long.

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