Expansion Tank Sizing Calculator (Potable)

TO PROPERLY SIZE A WATTS REGULATOR SERIES PLT OR DETA POTABLE WATER EXPANSION TANK:

Enter the appropriate information in the boxes below..

* Required Fields

Water Heater * Gallons
Initial Pressure *
Building cold water pressure. Typically does not exceed 80 PSI as per UPC plumbing code.
PSI
Air Pre-Charge *
Tank’s air pre-charge should be adjusted to match Initial Pressure. Never exceed 80 PSI pre-charge!

 PSI
Final Pressure *
Initial Pressure plus 50%. This entry should never exceed 85% of T&P relief valve pressure rating!

PSI
Inital Temperature - Start *
NOTE: Set the cold water start temperature to 90°F. Lower start temperatures should only be used if the entire contents of the water heater are drained on each use.
°F
Final Temperature - End * °F
Expansion Factor
Calculated Acceptance Volume Gallons
Calculated Total Volume Gallons
WATTS
Model		 Tank
Volume
(Gal) 		Tank
Acceptance
(Gal) 		MAX.
PRESSURE
(PSI)
Residential Tanks »More Info.
PLT-5 2.1 1.26 150
PLT-12 4.5 2.8 150
PLT-20 8.5 3.2 150
PLT-35 14 5.6 150
Commercial Tanks (ASME CODE) »More info.
DETA-5 3.5 2.3 150
DETA-12 5.0 3.3 150
DETA-20 8.0 5.3 150
DETA-30 15.0 10.0 150
DETA-42 22.0 14.5 150
DETA-60 26.0 17.5 150
DETA-80 35.0 23.5 150
DETA-100 45.0 30.0 150
DETA-125 60.0 40.0 150
DETA-160 70.0 47.0 150
DETA-180 80.0 53.0 150
DETA-210 90.0 60.0 150
HIDE CHART

How do I size my expansion tank?

  1. Using the calculated acceptance volume and the calculated total volume, select a tank from the chart to the right.
    • Tank volume of the selected model must be greater than the calculated total volume.
    • Tank acceptance of the selected model must be greater than the calculated acceptance volume.
    Note: Both the Tank Volume and the Acceptance Volume must be greater than the calculated volumes as indicated.
  2. A pressure reducing valve should be installed on the supply when system pressure exceeds 80psi.
  3. To accommodate the thermal expansion required for higher temperature and/or higher pressure systems, multiple tanks may be used. Please contact the factory for sizing information.
  4. For complex tank sizing for multiple apartments/condos, please contact the factory for sizing information.
  5. The potable water expansion tank shall be installed in the cold water service pipe line on the supply side of the water heater (or water storage tank).



IMPORTANT: This Watts thermal expansion tank sizing tool should be used as a general guide to sizing thermal expansion tanks. Sizing calculations are wholly dependent on user input and are therefore only as accurate as the sizing criteria entered by the user. Use of this tool does not constitute a guarantee that the results obtained are suitable for any specific application.


Watts product specifications in U.S. customary units and metric are approximate and are provided for reference only. For precise measurements, please contact Watts Technical Service. Watts reserves the right to change or modify product design, construction, specifications, or materials without prior notice and without incurring any obligation to make such changes and modifications on Watts products previously or subsequently sold.