A Water Heater Expansion Tank on Top of your Tank Water Heater is Crucial

A water heater expansion tank is that little metal tank that should be located above your tank-style water heater. It looks a bit like a small propane tank.

Water heater thermal expansion tank is small tank at top of water heater

What’s the Purpose of A Thermal Expansion Tank?

In short, it’s there to protect your home from excessive pressure building up in the tank water heater. As water heats up in the water heater, it expands.

A 50-gallon tank water heater full of cold water, for example, expands to 52 gallons when it heats up. That excess water from the heat needs somewhere to go. So the job of this little thermal expansion tank is to take on that excess water. That’s why a 50-gallon tank water heater needs at least a 2-gallon thermal expansion tank. This little tank can also absorb extra pressure from the incoming water supply.

Dale Anderson Adds an expansion tank to a tank water heater

Owner Dale Anderson, a second-generation plumber in Fallbrook, adds a thermal expansion tank to a water heater before installing it in a customer’s home.

We’re often asked what that little tank on top of the water heater is used for. Well, it’s pretty darned important. And we always install them on every tank water heater.

What if You Have More than One Water Heater in Your Home?

It’s best to have a thermal expansion tank for each water heater.

What Could Happen if You Didn’t Have an Expansion Tank … or it was Faulty?

The excess pressure from the water heater could damage your home. Water could overflow, damaging whatever is in its path plus the water heater itself and its fittings. Worst case scenario, if the pressure release valve on the water heater is also damaged, the water heater could even explode.

So an expansion tank, however, is not a substitute for the water heater’s temperature release (TPR) valve. According to the International Association of Certified Home Inspectors (InterNATCHI) If the TPR valve fails water becomes superheated. When that superheated water is exposed to air and become explosive steam. “This situation can propel the water heater like a rocket or make it explode like a bomb, causing extensive property damage, personal injury or death.”

In theory, if you don’t have a a water heater expansion tank on top of your tank water heater, the excess pressure might push back the excess water into the municipal water supply. But that’s only IF you don’t have a pressure regulator installed on your home’s water supply system.

However, you NEED a pressure regulator valve! Pressure regulators protect your home’s plumbing and fixtures by preventing too much pressure from rupturing your water pipes and damaging your water fixtures. We always check the pressure regulator valve before we start any plumbing project. More on that here.

Mineral Deposits in our “Hard” Water area Also Causes Water Heater Problems

We live in an area here in Fallbrook, Bonsall, Vista, Oceanside, and Temecula with some of the highest mineral deposits in the west. (Read more about our mineral content here.) Those minerals can build up within the pipes to and from the water heater as well as inside the water heater. This hard build up shortens the life of the water heater and all water appliances.

That’s why we offer water treatment solutions like water softener systems and water purification systems. Read about them here. Or Call us! We’re happy to discuss your specific needs and possible solutions.

Inspecting it is part of Our Routine Water Heater Maintenance Program

The expansion tank, like all parts of a water heater, can wear out, corrode or leak. And water heaters have several important valves and gauges. It’s important that they’re ALL in good working order. If any of them are damaged or corroded, it will be impossible to regulate the water flowing back and forth between the water heater and the little expansion tank. That’s one reason why routine water heater inspections are important.

We’re the water heater experts. In fact, we’ve installed and maintained more types and brands of water heaters than any plumber in the area.

Call us to inspect and maintain your water heater at least every couple of years. It will give you peace of mind to know everything is in good working order.

Do You Need an Expansion Tank on a Tankless Water Heater?

No. That’s because a tankless water heater only heats water on demand. It doesn’t store hot water.

A tankless water heater
A tankless water heater like this one does not need a thermal expansion tank.
Tank-style water heater
A tank-style water heater like this one being installed in a customer’s home needs the expansion tank you see at the top right.

We offer both tank-style water heaters and tankless (aka: on-demand) water heaters. Find out more here about the benefits of each one.

Live in Fallbrook, Temecula, Oceanside or Vista? Need a Water Heater Expansion Tank or Tankless Water Heater? Call us!

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