Pros, Join Our TradeMaster Program!
Zilmet has over 50 years of experience in manufacturing high quality diaphragm expansion tanks
  • Over 2 million square feet of production space
  • Has produced over 7.5 million tanks and over 1 million heat exchangers
  • Fully vertically integrated, designing and manufacturing all diaphragms internally
Zilmet has created a compact design with a seamless diaphragm that never stretches or creases.
  • There are no bubbles or corners to trap sediment, inhibiting bacterial growth
Technical Features:
  • Each tank is factory leak tested to ensure tank integrity
  • Certified synthetic SBR rubber diaphragm
  • All diaphragms designed to maximize drawdown
  • MIG welding eliminates interior rough spots and sharp edges
  • Welded side outlet allows easy and quick installation
  • Low profile tank design with full membrane depth eliminates stretching of diaphragm, providing increased life cycle
  • External baked on epoxy-polyester coating provides a durable, appliance like finish
  • Protected pre charge valve eliminates potential leak path
  • 5 year warranty on all models
  • Tank customization available upon request
In a closed heating system water cannot be compressed and any increase in water volume due to the increase of its temperature is absorbed by the expansion vessel. When water is cold, the precharge pressure of the tank presses the diaphragm against the tank. As temperature increases, the expanded water volume pushes against the membrane and water enters the tank, providing additional space to the system. With the temperature decrease, the air cushion forces water back into the system. This permits the system to maintain the pressure, helping to reduce energy consumption of the heating system
Hide Description
Manuals (2)
Tank Volume:

13.2 Gallons

Max Accepted Volume:

8.1 Gallons



Diameter (Inches):


Connection Type:


Connection Size:




Max Pressure (PSI):


Precharged PSI:

12 psi

Max Operating Temp:



5 Year

2 Videos

    Product Review

    Product Q&A

    Add-on Item

    This item is cost-prohibitive to ship on its own but is available to ship with orders over $200.

    Why don't we show the price of this item?

    We try to always offer you the lowest prices possible, but some manufacturers require that we only show these low prices once you take further action.

    To see the price, simply add the item to your cart or sign in.