Expansion Vessel Sizing Calculator

September 18, 2023 by GEGCalculators

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System Water Volume (Gallons)	Recommended Expansion Vessel Size (Gallons)
Up to 25	2
25 – 50	4
50 – 100	6
100 – 200	10
200 – 300	15
300 – 500	20
500 – 750	25
750 – 1000	35
1000 – 1500	45
1500 – 2000	65
2000 – 2500	80
2500 – 3000	100

FAQs

How do you calculate expansion vessel size? The expansion vessel size can be calculated based on the system’s total water volume, the maximum temperature change, and the desired pressure increase. A rough estimation is to use a 10% to 15% expansion vessel size relative to the system’s water volume.

What size expansion vessel should I use? A typical rule of thumb is to choose an expansion vessel that is about 10-15% of your system’s total water volume.

Can an expansion vessel be too big? Yes, an expansion vessel can be too big. It may not provide effective pressure relief in a smaller system, and it could lead to over-pressurization issues.

What happens if the expansion vessel is too small? If the expansion vessel is too small, it won’t have enough capacity to absorb the expanding water, leading to excessive pressure in the system and potential damage.

What PSI should the expansion vessel be? The recommended PSI for an expansion vessel is typically set to match the system’s cold water supply pressure, which is often around 12-15 PSI.

What is the difference between a red and white expansion vessel? Red expansion vessels are typically designed for heating systems, while white expansion vessels are commonly used for domestic water supply systems.

Will a bigger expansion tank increase water pressure? No, a larger expansion tank won’t increase water pressure. Its primary function is to accommodate thermal expansion and prevent over-pressurization in the system.

What happens if the expansion tank is too high? If the expansion tank is installed too high, it may not function correctly and could lead to pressure-related issues. It should be installed at the proper height based on manufacturer recommendations.

What happens if the expansion tank is full of water? If the expansion tank is full of water, it loses its ability to accommodate thermal expansion, rendering it ineffective. It should contain air to function properly.

Can I replace an expansion vessel myself? You can replace an expansion vessel yourself if you have the necessary knowledge and skills. However, it’s often recommended to hire a professional plumber or technician to ensure proper installation.

Should an expansion vessel be full of water? No, an expansion vessel should not be full of water. It should contain air to provide the necessary pressure relief.

Can a faulty expansion vessel cause pressure loss? Yes, a faulty expansion vessel can cause pressure loss in a system, as it may not effectively absorb the expanding water, leading to increased pressure fluctuations.

How much pressure do I need in my expansion tank? The pressure in the expansion tank should match the cold water supply pressure, typically around 12-15 PSI.

How do I know what PSI my expansion tank is? You can check the pressure of your expansion tank using a pressure gauge, typically installed on the tank. It should read around 12-15 PSI when the system is at rest.

Is it bad to oversize an expansion tank? Oversizing an expansion tank won’t necessarily cause harm, but it may lead to unnecessary costs. It’s best to choose an appropriately sized tank for your system.

Will an expansion vessel stop water hammer? An expansion vessel primarily addresses thermal expansion, not water hammer. Water hammer is typically controlled through the use of water hammer arrestors or other specialized devices.

What is the life expectancy of an expansion tank? The life expectancy of an expansion tank can vary but is generally around 5-10 years. Proper maintenance and regular inspection can help prolong its lifespan.

How much water should be in the expansion vessel? An expansion vessel should not have water inside; it should be filled with air.

Does an expansion vessel need to be above a cylinder? The expansion vessel should be installed in a way that allows it to maintain proper pressure relief, but it doesn’t necessarily need to be above the cylinder.

Can you use a white expansion vessel for heating? White expansion vessels are typically designed for domestic water systems. It’s recommended to use a red expansion vessel specifically designed for heating systems.

Can you have two expansion vessels? Yes, you can have two expansion vessels in a system if it’s large or complex, but they should be properly installed and sized.

Where is the best place to put an expansion vessel? The best place to install an expansion vessel is on the cold water supply line, typically close to the water heater or heating system.

Should an expansion vessel be on the cold or hot side? An expansion vessel is usually installed on the cold water supply side of the system.

Can I install an expansion tank myself? You can install an expansion tank yourself if you have the necessary knowledge and skills, but it’s often recommended to hire a professional plumber for safe and proper installation.

What is the average size pressure tank for a house? The average size of a pressure tank for a house can range from 20 to 80 gallons, depending on the household’s water needs and usage.

What is good water pressure for a well? Good water pressure for a well typically falls within the range of 40 to 60 PSI.

Can you run 2 pressure tanks on a well? Yes, you can run two pressure tanks on a well system to increase water storage and maintain consistent pressure.

Does it matter if the expansion tank is upside down? The orientation of the expansion tank can affect its performance. It should be installed according to the manufacturer’s instructions to function correctly.

Does expansion tank position matter? Yes, the position of the expansion tank matters. It should be installed in a vertical position with the air valve pointing upward for proper operation.

Should I bleed my expansion tank? Bleeding an expansion tank is not necessary as long as it’s properly installed and maintains the correct air pressure.

How often should I drain my expansion tank? Draining an expansion tank is not a regular maintenance task. It should only be done if there are specific issues or during replacement.

Should the water in the expansion tank be hot? No, the water in the expansion tank should not be hot; it should be at ambient temperature.

How do I stop my expansion tank from overflowing? If an expansion tank is overflowing, it may indicate a problem with the system, and you should consult a professional plumber to diagnose and resolve the issue.

How much does it cost to fit a new expansion vessel? The cost of fitting a new expansion vessel can vary widely depending on factors like the size of the vessel, labor costs, and location. It could range from $100 to $500 or more.

What is the average cost of expansion tank replacement? The average cost of expansion tank replacement can range from $50 to $200 for the tank itself, plus labor costs if you hire a professional.

What can I use instead of an expansion tank? There isn’t a direct substitute for an expansion tank in a pressurized water system. Using anything other than a properly sized and designed expansion tank could lead to system damage.

Why does my expansion vessel keep losing pressure? A loss of pressure in an expansion vessel could be due to a leak in the tank or issues with the system, and it may need to be replaced or repaired.

Why does my water pressure keep dropping? Water pressure fluctuations can be caused by various factors, including system leaks, clogs, or problems with the pressure tank or expansion vessel.

Why would an expansion tank burst? An expansion tank can burst if it’s subjected to excessive pressure, either due to a malfunction or incorrect sizing. Proper installation and maintenance are essential to prevent this.

What happens if my expansion tank pressure is too low? If the expansion tank pressure is too low, it won’t effectively absorb thermal expansion, potentially causing pressure fluctuations in the system. It should be repressurized to the recommended level.

What size expansion tank do I need? The size of the expansion tank you need depends on the system’s total water volume. A common rule of thumb is to use a tank that’s 10-15% of the system’s water volume.

What is the maximum PSI for an expansion tank? The maximum PSI for an expansion tank typically matches the cold water supply pressure, which is often around 12-15 PSI.

Should water come out of the expansion vessel? Water should not come out of the expansion vessel; if it does, there may be a problem with the tank or the system.

Can an expansion tank burst? Yes, an expansion tank can burst if it’s subjected to excessive pressure or if it’s faulty. Proper sizing and maintenance can help prevent this.

What happens if the expansion vessel is too small? If the expansion vessel is too small, it won’t have the capacity to absorb thermal expansion, leading to increased pressure and potential system damage.

How do I know when my expansion tank needs to be replaced? Common signs that an expansion tank needs replacement include a loss of pressure, waterlogged tank, or visible damage.

Does an expansion tank extend the life of a water heater? An expansion tank helps protect the water heater and the overall plumbing system but doesn’t necessarily extend the water heater’s lifespan.

Can a bad expansion tank cause high water pressure? Yes, a malfunctioning expansion tank can contribute to high water pressure in the system due to its inability to absorb expanding water.