118-78 Extrol SX-40V Amtrol (SX-40V) Expansion Tank  20.0 G

The 118-78 from Amtrol is a Extrol SX-40V Expansion Tank (20.0 gal). It's designed to relieve pressure in a radiant heating or closed loop hydronic heating systems. This tank uses a rubber diaphragm to divide its components to ensure the proper amount of pressure is applied to the system. This is done by filling the top portion of the tank with water, and bottom portion with air, set at approximately 12 PSI. This configuration allows for the relief of excess pressure in a heating system, while contributing to the safety of the piping. This model has a base that allows it to stand on its own.

Technical Specifications:

  • Floor standing model;
  • Factory pre-charged 12 psi;
  • System connection: 1" threaded;
  • ax. operating temperature: 240F;
  • Max. operating pressure: 100 psig;
  • Expansion tank volume: 20.0 gallons;
  • Max. accepted volume: 11.3 gallons;
  • Height: 32-1/2";
  • Diameter: 15-3/8";
  • Shipping weight: 33 lbs.


  • 1-year manufacturer's warranty. 
20 Gallons
Product Type
Expansion Tank

118-78 Extrol SX-40V Amtrol (SX-40V) Expansion Tank 20.0 G

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  • 118-78 Extrol SX-40V Amtrol (SX-40V) Expansion Tank  20.0 G  QR Code
  • Brand: Amtrol
  • Model: 118-78
  • MPN: 118-78
  • Availability: 5
  • $ 265.95

Tags: Amtrol, Expansion Tanks, Heating Supplies, Radiant Heating System, Heating and Cooling