The ultimate guide to mounting expansion tanks: upside down or right side up?

Expansion tanks are crucial components in heating and cooling systems, maintaining pressure balance and preventing system damage. However, doubts often arise regarding the correct mounting orientation of these tanks, leading to the question: can you mount an expansion tank upside down? This blog post aims to delve into this topic, uncovering the facts and dispelling any misconceptions surrounding the proper installation of expansion tanks.

Function of an Expansion Tank

Expansion tanks play a vital role in closed-loop hydronic systems. As water expands when heated and contracts when cooled, the expansion tank provides a buffer zone to accommodate these volume changes without excessive pressure buildup. The tank’s membrane or diaphragm separates the water from a compressed gas, typically air or nitrogen.

Consequences of Upside-Down Mounting

Mounting an expansion tank upside down can lead to several adverse consequences:

• Trapped Air: The gas-filled side of the tank should be at the top, while the water-filled side should be at the bottom. Upside-down mounting traps air in the water-filled section, reducing the tank’s effective volume and impairing its ability to handle expansion.
• Reduced Efficiency: The trapped air interferes with the water’s flow into the tank, reducing its efficiency in absorbing pressure fluctuations. This can lead to system instability and potential damage to other components.
• Premature Failure: The trapped air can cause corrosion and premature failure of the tank’s membrane or diaphragm, shortening its lifespan.

Proper Mounting Orientation

To ensure optimal performance and longevity of the expansion tank, it must be mounted correctly:

• Vertical Position: Mount the expansion tank vertically, with the water inlet and outlet at the bottom.
• Upright Membrane: If the tank has a removable membrane, ensure it is installed upright, with the gas-filled side facing up.
• Adequate Support: Provide adequate support for the tank to prevent movement or vibration.

Expansion Tank Location

In addition to proper orientation, the location of the expansion tank is also crucial:

• Highest Point: Install the tank at the highest point in the system to prevent air from accumulating in the tank.
• Accessible for Inspection: Choose a location that allows for easy access for inspection and maintenance.
• Avoid Direct Sunlight: Protect the tank from direct sunlight to prevent damage to the membrane or diaphragm.

Types of Expansion Tanks

Expansion tanks come in various types, each with its own specific mounting requirements:

• Diaphragm Tanks: These tanks have a removable rubber diaphragm that separates the gas and water. They require upright mounting with the diaphragm facing up.
• Bladder Tanks: Similar to diaphragm tanks, bladder tanks have a rubber bladder that separates the gas and water. They also require upright mounting.
• Closed-End Tanks: These tanks do not have a diaphragm or bladder. They are partially filled with water and air and are mounted horizontally.

Precautions

Before mounting an expansion tank, take the following precautions:

• Check Manufacturer’s Instructions: Refer to the manufacturer’s instructions for specific mounting requirements.
• Use Approved Fittings: Ensure the tank is connected using approved fittings that are compatible with the system.
• Bleed the Tank: After installation, bleed the tank to remove any trapped air.

Final Thoughts

Mounting an expansion tank upside down is generally not recommended. It can lead to reduced efficiency, premature failure, and system instability. By following the proper mounting orientation, location, and precautions, you can ensure optimal performance and longevity of your expansion tank.

What People Want to Know

Q: What happens if I mount an expansion tank horizontally?
A: Horizontal mounting is only suitable for closed-end tanks. Other types of tanks require vertical mounting for proper operation.

Q: How often should I check my expansion tank?
A: Regularly inspect your expansion tank for any signs of leaks, corrosion, or damage. Bleed the tank annually to remove trapped air.

Q: Can I use a different gas than air or nitrogen in my expansion tank?
A: No, it is not recommended to use other gases in expansion tanks. Air or nitrogen are the preferred gases for maintaining system pressure.