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How Thermal Expansion Relief Valves Replace Expansion Tanks


When it comes to keeping your customers comfortable, a water heater system plays a significant role. However, unbeknownst to the homeowner, not all parts of the system are efficient or reliable enough to maintain uninterrupted comfort. 

Expansion tanks are one of those items that tend to need replacing before other parts of the system. To address this short lifespan, look to a thermal expansion relief valve.

These offer a longer-lasting alternative for your customers by replacing the bulky expansion tank, shut-off valve and fitting right at the water heater for an easier-to-install solution. 

Thermal Expansion Relief Valves vs. Expansion Tanks 

The thermal expansion relief valve can replace a water heater expansion tank because it functions similarly. Both products absorb the excess pressure in the plumbing system created by thermal expansion. As plumbers know, the expansion tank equalizes pressure throughout the plumbing system by providing a space for hot water to flow into. Without an expansion tank, pressure would be distributed to the entire plumbing system, straining it and decreasing its lifespan. 

Like an expansion tank, the relief valve also takes the load off your pipes by: 

  • Equalizing pressure
  • Managing thermal expansion of water
  • Keeping pipes from bursting or wearing out prematurely 

Instead of storing water, though, it releases it, solving some of the problems that come with using an expansion tank.

Common Expansion Tank Problems 

While expansion tanks are required by code in most closed-loop water heater systems, they have a reputation for failing. Common expansion tank issues include: 

  • Rubber diaphragm wear-out. For example, the pressure below the rubber diaphragm in the tank may not have been set at the right level during installation, allowing water to enter the tank too frequently and wearing out the diaphragm prematurely.
  • Pinhole leaks. Expansion tanks are also known for developing pinhole leaks in the rubber bladder, and there’s no way to know without going out of your way to test it or by noticing that the temperature & pressure (T&P) relief valve is going off frequently.
  • Excessive condensation issues. Tanks can also become coated in condensation if there’s too much water in the tank, which can lead to messy pooling, dangerous dripping and eventually a rusty expansion tank. 

Because there are coordinating valves and parts both outside and inside a water heater that determine whether water pressure is effectively and safely managed, there are many failure points that could lead to damaged plumbing systems — all without warning

Watch How to Install SharkBite Thermal Expansion Relief Valve on YouTube.

Why You Should Use a Thermal Expansion Relief Valve 

When you need more time in your day and want to keep your customers happy, you need reliable solutions that help you finish the job faster while remaining cost-effective. Here are a few ways thermal expansion relief valves set you up for success.  


There’s no guesswork with the thermal expansion relief valve. Installed in the same place as an expansion tank, it’s a combination of a ball valve with a relief valve that opens and drains water to a pipe drain once water pressure hits 125 psi. That means no wondering if a diaphragm or bladder is working properly, no inevitable replacement. And the best part? It meets code requirements. 


It’s easier for you to install, too, since there are no bulky items to work around when putting everything in place. No matter how big or small the area around the water heater is, you don't have to worry about finding space for a tank anymore. Made with SharkBite push-to-connect end connections that are compatible with PEX, copper, CPVC and PE-RT pipe, the thermal expansion relief valve simply goes onto the water line — no extra support needed. 


With ease comes affordability. While expansion tank installations require several accessories that add up, for a thermal expansion relief valve, all you need is the valve and a drain line. This saves on parts and labor costs by speeding up service times. 

Key Takeaways 

While expansion tanks have been the norm to keep thermal expansion from damaging plumbing systems, they come with reliability issues, extra installation costs and a lot of space. Thermal expansion relief valves give you the functionality of an expansion tank without its problems. 

Compared to expansion tanks, the SharkBite thermal expansion relief valve: 

  • Is easier and faster to install with multiple pipe compatibilities.
  • Has a longer lifetime.
  • Is perfect for tight spaces.
  • Requires no additional tools, saving you time and money.
  • Absorbs excess pressure by releasing water instead of storing it.  

Install one today. 

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