Zilmet Solar High Temp Expansion Tank -18 L (4.8 G)

Zilmet Solar High Temp Expansion Tank -18 L (4.8 G)


Zilmet Solar Expansion Tank 18 Liters 4.8 USG Italian Made Zilmet Solar Expansion Tank - Specifically designed for high temperature solar vacuum tube heating applications. The tanks use a patented Zilan High Temperature membrane t Read More
  • Shipping Weight: 8kgs
  • Manufactured by: Zilmet
0 Units in Stock
 Sold Out 

Zilmet Solar Expansion Tank

18 Liters 4.8 USG

Italian Made Zilmet Solar Expansion Tank - Specifically designed for high temperature solar vacuum tube heating applications. The tanks use a patented Zilan High Temperature membrane that can withstand temperatures up to 212°F.  The Zilmet expansion range is a well suited product for all solar heating system's, especially when using high temperature solar vacuum tubes. The Zilan Membrane of the tanks can withstand mixture of glycol up to 60%.

Expansion Tank Principle

how solar expanion tank works

cold  system - water pressure = air pressure in tank

hot system - water pressure > air pressure in tank



The expansion tanks have a rubber membrane which separates the solar liquid loop and the other side is filled with pressurized air. As the liquid heats up and expands the pressure of the system increase to an amount greater than the air pressure inside the expansion vessel and causes the membrane to take up more liquid to the air side.  This keeps occurring until the expansion tank is completely filled.  At that point the pressure of the system has no where to go and will quickly be release through a pressure release valve causing hot glycol to spill over the floor.  In order to prevent this, the expansion tank must be sized correctly and the correct initial pressure of the tank must be equal to the design pressure of the system when cold.


This is probably the most important part of designing a solar heating system and has many variables.  However we take the guess work out of sizing by proving complete solar system packages with the tank size already factored into the design.  You can be assured that when purchasing any of our solar heating system you will be supplied with a safe and reliable expansion tank capable of allowing your system to safely stagnate.  For those that want more information on sizing of expansion tanks click on link.

Sizing Chart


Capacity Liters

Capacity Gallons

Max Pressure PSI

Dimension Diameter

Dimensions Height

Connection Size







3/4" NPT







3/4" NPT







3/4" NPT







3/4" NPT







1" NPT

  • Patented Zilan Membrane resistant up 212F
  • Screwed Stainless Steel Flange
  • 36 PSI Pre-Charged
  • CE Certified
  • Floor stand on 40,60,80 Liter Models
  • 3 Year Warranty

Return Policy

We want you to be 100% satisfied with your purchase, if you are not, ship it back to us in the original packaging condition and we will refund your purchase less a 10% restocking fee, provided the equipment is received in good condition. Refund offer valid for 30 days from receipt of product.


We feel that being honest is a much better policy to win your trust rather than trying to lure you with nearly impossible statements such as life time warranty. Nothing lasts forever! Our warranty policy is simple; we offer a 3 year warranty on everything we sell and 10 years on our collectors. With this warranty you will get NO hassle next business day replacement (if shipping service and inventory permits). However, as a valued customer you will get technical support through the life time ownership of your product. Our Collector do carry longer warranties 10 years from the manufacture. The warranty cover failures that occur during normal operational conditions or manufactures defects. It does not cover failure due to inappropriate operation such as freezing or over heat. Damage caused by vandalism, storms, floods etc. Your household insurance should be modified to cover the system from such situations.

We accept PayPal and Credit card (Visa or Mastercard). If you are ordering multiple units and part, please call us to see if we can save you shipping cost for multiple item orders.


For complete solar kits please allow 2-3 weeks delivery. These kits are shipped via our preferred freight forwarder company and where possible we will schedule residential tailgate delivery (curbside). Heaters and accessories are usually in stock unless indicated otherwise. We do have expedited shipping services available for an additional fee. Please call us if you need a rush order. Once your order has been shipped you will be contacted via email and a tracking number will be provided.

 Sold Out 

Current Reviews: 0

This product was added to our catalog on Friday 11 April, 2014.