Therm-X-Trol ST-8 Thermal Expansion Tank (3.2 Gal Volume)


Brand: Amtrol

Mfr Part#: 140N738

Model: ST-8

Availability: In Stock
Usually ships: within 1 business day
Qty Price
$47.95 / each
x4 $183.80 & Free Shipping
(4 x $45.95 / each)
  • Description
  • Literature
  • Reviews (1)
  • FAQs (1)

Amtrol ST-8 is 3.2 gallons In-Line Model of Therm-X-Trol searies expansion tank designed to control pressure build-up in closed, hot water systems. Equipped with the thickest diaphragm that provides extra strength and flexibility. Polypropylene tank liner provides 100% corrosion resistance and complies with NSF International Standard for clean and safe water storage.


Materials of Construction:

  • Shell: Steel;
  • Diaphragm: Butyl;
  • Liner: Polypropylene;
  • System Connection: Stainless Steel.

Technical Specifications:

  • Tank Volume 3.2 Gal (12 Lit);
  • Maximum Acceptance Factor 0.59;
  • Maximum Operating Temperature: 200°C (93°C);
  • Maximum Working Pressure: 150 PSIG (10.3 bar);
  • System Connection (NPTM): 3/4";
  • Tank Height x Diameter: 15" x 9" (381 mm x 229 mm);
  • Shipping Weight 7 lb (3 Kg).


5 years manufacturer's warranty.
Therm-X-Trol ST-8 Thermal Expansion Tank (3.2 Gal Volume) has an average 5.0 out of 5 rating based on 1 user review.
1 of 1 people found this review helpful.
Good sized
By Verified Buyer on 6/17/2016
I wanted this size as it is just slightly oversized for my needs...50 gal water heater and 60 psi pressure. I was seeing 75 psi avg and excursions up to 120 psi before I put in pressure regulator and expansion tank. Now I only see 60 psi avg and 70 psi peak.
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Do you have a wall mount for the Therm-X-Trol ST-8 Thermal Expansion Tank 3.2 Gal?
Read 1 answer
Yes. It's part# 598-0210
Answered on 12/12/2016 by PexUniverse Customer Service
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