Expansion Tank Pressure Calculator

How to Use This Calculator

1. Enter the total volume of your hydronic heating system in gallons.
2. Input the initial water temperature in degrees Fahrenheit.
3. Enter the maximum expected water temperature in degrees Fahrenheit.
4. The water expansion coefficient defaults to 0.0012 (standard for water), but can be adjusted if needed.
5. Click the "Calculate" button to determine the required pressure increase and recommended expansion tank pressure.

Working Principle

The calculator uses the formula:

ΔP = V × (T_max - T_initial) × C_e

Where:

• ΔP is the pressure increase the expansion tank must handle
• V is the system volume in gallons
• T_max is the maximum water temperature in °F
• T_initial is the initial water temperature in °F
• C_e is the water expansion coefficient (typically 0.0012 per °F for water)

The recommended tank pressure includes a safety margin of 12 PSI above the calculated pressure increase.

Applications

This calculator is useful for:

• Designing hydronic heating systems
• Sizing expansion tanks appropriately
• Ensuring proper system pressure for safety and efficiency
• Understanding how temperature changes affect system pressure