2 Gallon Potable Water Expansion Tank Zoom

2 Gallon Potable Water Expansion Tank


Brand: AO Smith

AO Smith
PMC-2 has been discontinued.
Please contact customer service at
(888) 757-4774 for help finding an alternative.



Capacity (Gallons): 2
Max Pressure (PSI): 150
Max Temp (F): 140°F
Connection Size: 3/4"
Connection Type: Male NPT
Warranty: 5 Year Limited Warranty

Description for AO Smith PMC-2

Thermal expansion occurs when water is heated during non-use periods. The installation of a Pressure Reducing Valve (PRV), Check Valve or Back Flow Preventer "closes" the water system, leaving water with no room for expansion. National Standard Plumbing code: 10.5.7 requires backflow prevention, to prevent backflow into the water main.

Thermal expansion in a closed plumbing system can be damaging, dangerous and costly. Its effects include damage to water heater connections, gas water heater flue tubes, pumps serving washers and dishwashers, leaking faucets, "weeping" of water through the water heater T&P Relief Valve, and noisy water hammer in the pipes.

A properly sized Expansion Tank eliminates these problems, by giving water a place to go when thermal expansion occurs. When a water heating cycle ends, or when any fixture is opened within the system, the impact of thermal expansion is reduced, and water drains out of the expansion tank back into the system.


  • Maximum Working Pressure: 150 PSI
  • Maximum Temperature: 140°F Residential, 180°F Commercial
  • For use with residential and commercial water heaters
  • In-line design, with 3/4" NPTM connection: installs in cold water line of water heater
  • Field-adjustable 38 PSI air charge
  • Drawn-steel tank with 2-coat bonded polymer inner lining
  • Butyl diaphragm, for permanent separation of air and water, with no waterlogging
  • IAPMO Approved
  • 5-Year Limited Warranty

2 Gallon Potable Water Expansion Tank


by PowerReviews
AO Smith2 Gallon Potable Water Expansion Tank

(based on 1 review)

Ratings Distribution

  • 5 Stars



  • 4 Stars



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  • 2 Stars



  • 1 Stars



Reviewed by 1 customer

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Solid, well-made

By Michael

from Chicago, IL

Verified Buyer

Comments about 2 Gallon Potable Water Expansion Tank:

It's a good, solid, well-made tank that worked beautifully the moment it was installed. I selected this brand/model because the tanks at local hardware outlets, although cheaper, usually had reviews referring to them as "cheap" and "flimsy." This one's neither: I dropped it from a height onto concrete before installation (not on purpose) and it suffered no ill effects

  • Was this a gift?:
  • No

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