what is a thermal expansion tank


Plumbing systems have come a long way over the last few decades. As technology and safety precautions increase, so do the components needed to stay up to code. After a long day at work, it’s nice to relax by taking a hot shower. We all know how our water is heated. You’ve seen your water heater, and maybe you’ve done some maintenance on it yourself. If it’s been replaced in the last 20 years, there’s a good chance you have a thermal expansion tank on top of the heater. You may wonder: what is a thermal expansion tank? Well, we’re going to tell you all about it.


What Is Thermal Expansion?


Before we dive into what a thermal expansion tank is, you need to first understand what thermal expansion means.

When water is heated and the temperature rises, so does the overall volume. As the volume of water inside the tank increases, so does pressure. So, with thermal expansion, you have an increase in three factors: temperature, volume, and pressure. If this pressure is allowed to keep increasing without regulation, the excess of pressure has the potential to damage valves, connections, pipes, fixtures, and the water heater tank itself. It may not sound like a lot, but water heated from room temperature to boiling increases volume by four percent.

Now, in order to deal with this excess pressure and prevent any damage from taking place, modern plumbing innovation has produced the thermal expansion tank. These seemingly small tanks prevent significant damage or injury from taking place. So, now, let’s look at how they work.


What Is A Thermal Expansion Tank And How Does It Work?


A thermal expansion tank is a small, metal tank installed above your water heater. Inside the tank, there’s a small diaphragm that holds a pocket of air. When the water is heated and expands, the excess pressure and water are pushed into the thermal expansion tank. This acts as a form of pressure relief that keeps the water heater’s pressure levels in a safe range. Next, when a faucet or shower is turned on, the drop in pressure in the water heater tank causes the air diaphragm to push the water from the expansion tank back to the heater.

So, thanks to your thermal expansion tank, you’re plumbing won’t suffer the consequences of too much pressure. Do you need a thermal expansion tank if you’re on a well? Typically, no. If you’re on a well, there is a well tank that acts as a thermal expansion tank.


Questions About Your Water Heater?


This is only a surface-level look at thermal expansion tanks. While it may be tempting to install one yourself, we suggest calling a professional plumbing service. There are specific pressure levels and temperatures the tank and heater should be set in order to work properly. So, it’s best to leave it to the pros.


Give us a call today, and get on our schedule!