Expansion tanks and water pressure: the connection you need to know

In a typical plumbing system, an expansion tank plays a crucial role in maintaining optimal water pressure. However, understanding the relationship between the expansion tank and water pressure can be confusing. This blog post aims to clarify the impact of expansion tanks on water pressure, exploring their purpose, function, and common issues.

What is an Expansion Tank?

An expansion tank is a pressurized vessel installed in a plumbing system to absorb excess pressure created by thermal expansion of water. As water heats up, it expands in volume. In a closed system, this expansion can lead to dangerously high pressure levels, potentially damaging pipes and fixtures.

How Does an Expansion Tank Affect Water Pressure?

Expansion tanks regulate water pressure by providing a buffer for the increased volume of water during heating. Here’s how they work:

• Expansion: As water heats, it expands and enters the expansion tank.
• Compression: The air or gas inside the tank compresses, creating a cushion to absorb the pressure.
• Regulation: The compressed air maintains a stable pressure within the system, preventing excessive pressure buildup.

Common Issues with Expansion Tanks

• Loss of Air or Gas: Over time, the air or gas inside the expansion tank can leak out, reducing its ability to absorb pressure.
• Waterlogging: If the expansion tank becomes filled with water, it loses its ability to compress and regulate pressure.
• Incorrect Sizing: An expansion tank that is too small or too large can lead to inadequate pressure regulation.

Troubleshooting Expansion Tank Issues

• Check Air or Gas Pressure: Use a pressure gauge to measure the air or gas pressure inside the tank. It should be around 12-15 psi.
• Drain and Refill: If the tank is waterlogged, drain it and refill it with the proper amount of air or gas.
• Inspect for Leaks: Check for leaks on the tank or its connections. Tighten any loose fittings or replace damaged components.
• Adjust Tank Size: If necessary, consider adjusting the size of the expansion tank to ensure it meets the needs of the system.

Does an Expansion Tank Increase Water Pressure?

While an expansion tank does not directly increase water pressure, it can indirectly contribute to maintaining stable pressure levels. By absorbing excess pressure caused by thermal expansion, the expansion tank prevents pressure spikes that could otherwise lead to reduced pressure at fixtures.

How to Test Expansion Tank Performance

• Check Pressure Gauge: Monitor the pressure gauge on the expansion tank to ensure it maintains a consistent pressure within the recommended range.
• Observe Fixtures: Pay attention to the water flow and pressure at fixtures. Reduced pressure could indicate an issue with the expansion tank or other system components.
• Inspect Tank for Leaks: Regularly inspect the expansion tank for any leaks or damage that could affect its performance.

FAQ

Q: Can I use a regular water heater tank as an expansion tank?
A: No, a water heater tank is not designed to handle the pressure fluctuations and thermal expansion of a plumbing system.

Q: How often should I check my expansion tank?
A: It is recommended to check the air or gas pressure in the expansion tank annually and inspect it for leaks or damage.

Q: Can a faulty expansion tank cause water hammer?
A: Yes, a malfunctioning expansion tank can lead to water hammer, which is a loud banging noise in the pipes caused by sudden pressure changes.

Q: What is the typical lifespan of an expansion tank?
A: Expansion tanks typically last 5-10 years, depending on the quality and usage.

Q: Can I replace an expansion tank myself?
A: Replacing an expansion tank is a relatively straightforward task for experienced DIYers. However, it is advisable to consult a licensed plumber for assistance if you are unsure.