Potable Water / Hydronic Expansion Tank Sizing Calculator 1. Water Heater / Boiler Total Water Capacity (Gallons) Gallons 2. Supply Line Pressure PSIG 3. Air Pre-Charge (Tank Pre-charge should equal supply line pressure) PSIG 4. Relief Valve PSIG 5. Start temperature 40 45 50 55 60 65 70 75 80 85 90 95 100 °F 6. Ending Temperature 50 55 60 65 70 75 80 85 90 95 100 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200 210 215 220 225 230 235 240 245 °F Click the button below to determine the total volume required. Minimum Acceptance Volume (Gallons) (Total expanded water to Accomodate) Minimum Tank Size (Gallons) Don’t know what size tank to choose? Always go bigger!
