Home Improvement

Is A Thermal Expansion Tank Necessary?

With winters on the way, it’s high time that you prepare for it in advance. Setting up a water heater is one of the most important things to do, but why is everyone talking about having an expansion tank as well. Is a thermal expansion tank necessary, or is it just a waste of resources? Let’s explore it here and find out.

What is thermal expansion?

It is the process in which a matter expands by mass or volume when its temperature is increased. It is all subject to the individual properties of a matter whether it expands in mass, volume, or in any other form.

Given this fact, when you use a water heater at your home, thermal expansion will take place, and given the plumbing condition of your house, it can turn out to be dangerous. Therefore, it becomes necessary that you know all about it.

Water heaters are used in almost every house. Operating continuously, it supplies hot water all day for our use. But, as the water expands, where did it go? It needs a path to pass through, but it will not find one if you have a closed plumbing system at your house.

Plumbing system

In order to determine if a thermal expansion tank is necessary or not, you need to see the plumbing system you have installed. It can either be a closed-loop system or an open system. An open system allows the water to flow in the reverse direction, back to the main water lines. Whereas a closed-loop system does not allow water to flow back once it enters your home.

Having said that, not only in the US but all around the world, most homes have a closed system.

It is because an open system has several disadvantages over a closed system that you cannot ignore. The foremost reason for this is that an open plumbing system can cause a health risk as it can contaminate the drinking water supplied by municipal authorities.

Other than that, a closed system is used because it protects the plumbing system from high-pressure water coming from the supplier. The water is supplied at extremely high pressure from the authorities, and to protect your pipes; closed systems are used that have pressure regulators or valves in place.

What does it all have to do with the thermal expansion tank? Let’s find out.

What is a thermal expansion tank?

Protecting your house in a way that only a few people recognize, keeping your house’s plumbing system in order is made possible with the installation of a thermal expansion tank.

A small tank with compressed air and a bladder inside, installed with your water heater, is what provides the way out to the water as a result of thermal expansion.

As the water starts expanding, the pressure build-up exceeds the compressed air inside an expansion tank. This leads the high-pressure water to make its way to the expansion tank keeping the overall pressure of a plumbing system at normal.

Keep in mind that the size of the expansion tank must be in line with the size of the water heater. As water expands, it should have enough space to accommodate the excess water.

The manufacturer knows about it all, and for this reason, you will see a pressure release valve on most of the water tanks as it regulates the pressure.

Is a thermal expansion tank necessary?

This brings us to our main question: is it necessary to have a thermal expansion tank along with the water heater? By considering the above information, yes, the thermal expansion tank is necessary if you have a closed plumbing system at your place. If you have an open plumbing system, then it is not necessary to go for a thermal expansion tank as well.

What happens if an expansion tank is not used?

As it is clear that the water will expand as the temperature is increased, now where the excess water will go if there is a closed plumbing system and there is no expansion tank installed. The expansion and the pressure buildup by water will cause the water heater to explode and will also damage the pipelines, fixtures, and appliances if it does not find a way out. An expansion tank is what absorbs the excess pressure developed from heating water and keeps the plumbing system in its working condition.

So, if you have a closed system and do not have an expansion tank, the thermal expansion may cause an explosion and can damage the overall plumbing system.


All appliances, fixtures, and the overall plumbing system of our housework are the best at a certain amount of water pressure. If it exceeds, all things are going to break down, and without a thermal expansion tank, you might face an explosion as well. Thus, a thermal expansion tank is one of the most crucial safety traits that you can go for. Protect your home from all aspects; check out if you need an expansion tank.