Potable Water Expansion Tank Sizing

Water Safety & Flow Control Support - Helpful Tools and Resources

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
Supply Pressure * The set pressure of the water pressure reducing valve or maximum system pressure.	PSI
Air Pre-Charge * 40psi Air Charge is Standard. Never exceed 80psi Pre-Charge.	PSI
Relief Valve * The set pressure of the T&P valve or the secondary relief valve setting.	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

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	1.3	150
DETA-12	5.0	3.1	150
DETA-20	8.0	3.1	150
DETA-30	15.0	10.5	150
DETA-42	22.0	15.5	150
DETA-60	26.0	15.5	150
DETA-80	35.0	15.5	150
DETA-100	45.0	21.0	150
DETA-125	60.0	21.0	150
DETA-160	70.0	52.5	150
DETA-180	80.0	52.5	150
DETA-210	90.0	52.5	150
HIDE CHART

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.
A pressure reducing valve should be installed on the supply when system pressure exceeds 80psi.
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.
For complex tank sizing for multiple apartments/condos, please contact the factory for sizing information.
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).