Expansion water tanks are a safety device helping to minimize the risk of pressure damage to your plumbing system.


Does your home’s heating system need an expansion tank? If you regularly use hot water, then the simple answer to this is ‘Yes.’ An expansion tank is built to deal with the water’s thermal expansion as it warms up in the heater. It ensures that the high-water pressure does not reach dangerous levels.

Plumbing fixtures, supply pipes joints and even the heater can get damaged if there is increased water pressure. For this reason, getting an expansion tank installed on your premises by a plumber in Prince William County, VA is a sensible thing to do.

When water is heated, it expands and volume increases. This thermal expansion puts an incredible amount of pressure on the piping and components of the entire system. If unresolved, this water pressure could cause leaks and even complete ruptures in the piping. Expansion tanks provide extra space for the expanded water and relieve the system’s pressure. Not having an expansion tank may result in the pressure opening your relief valve resulting in wasted energy, shortened system life, and an overall potential safety hazard. Although the water in your water heater doesn’t reach the boiling point and turn into steam, it does expand when heated up.

A safety device known as a water heater expansion tank (sometimes called a thermal expansion tank) can help minimize the risk of pressure damage to your plumbing system. When properly installed by a licensed plumbing professional, it absorbs this excess pressure.

For a small investment, you can have this expansion tank installed by the plumbing professionals at DB’s Plumbing & Drain®. The expansion tank takes unwanted pressure off of the water heater and puts it into the tank to control system pressure and help reduce energy consumption in water heating systems. Expansion tanks commonly have a life span of anywhere from 6-12 years and frequently longer between replacements. In some cases, water heater manufacturers require an expansion tank as a condition for warranty coverage.

When is it required?

An expansion tank is always highly recommended if you have a ‘closed-loop system’ caused by any kind of check valve or pressure regulating valve installed on your house’s water supply line.

Depending on where you live, an expansion tank might even be required by the city regardless of the water pressure in order to pass plumbing inspections. Expansion tanks are also required in a closed loop heating or chilled water HVAC system to absorb the expanding fluid and limit the pressure within a heating or cooling system. A properly sized tank will accommodate the expansion of the system fluid during the heating or cooling cycle without allowing the system to exceed critical pressure limits.


How to Size and Select a Proper Expansion Tank

The plumbing experts at DB’s Plumbing & Drain® will evaluate your needs and recommend a properly sized tank for your water system.

The decision will be based on two factors. The first is the capacity of your water heater. The second is the water pressure in your piping system. We will make this determination by attaching a gauge to a faucet to measure the pressure in your system.

If you do not install a properly sized expansion tank than what your system requires, the excess pressure from the expanding hot water will cause relief valve discharge. On the other hand, there is no problem with having an expansion tank that is larger than what your system requires. In fact, we may recommend installing an expansion tank that is one size larger than the required size. This will accommodate any unexpected pressure increase. As a general rule of thumb with expansion tanks, it is better to oversize than to undersize.


Expansion Water Tank


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