Skip to content

Amtrol ST-12 Thermal Expansion Tank

by Amtrol
In stock
Original price $68.79 - Original price $68.79
Original price
$68.79 - $68.79
Current price $68.79
Size: 4.4 Gallons


  • Shell: High Strength Steel
  • Diaphragm: Heavy Duty Butyl NSF/ANSI 61
  • Liner: Antimicrobial
  • System Connection: Stainless Steel
  • Water Circulator: Patented Turbulator™
  • Air Valve: Projection Welded
  • Air Valve Cap: Patented InSight™ Indicator Cap
    (In-Line Models: ST-5, ST-8, ST-12)
  • Factory Precharge:
    In-Line Models: 50 PSIG (3.5 bar)
    Stand Models: 40 PSIG (2.8 bar)


  • Max. Operating Temperature: 200º F (93º C)
  • Max. Working Pressure: 150 PSIG (10.3 bar)
  • Warranty:
    ST-1 through ST-12: 7-Year Limited
    ST-25V through ST-210V: 1-Year Limited


  • For use in closed, potable hot water systems to control pressure build-up and protect the water heater.
  • Accepts expanded water as system temperature rises and returns hot water to system when demand occurs.

Sizing Chart

Blog posts

Compare products

{"one"=>"Select 2 or 3 items to compare", "other"=>"{{ count }} of 3 items selected"}

Select first item to compare

Select second item to compare

Select third item to compare


Amtrol ST-12 Thermal Expansion Tank