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The ZILMET ZTTA-12 is a 5-gallon thermal expansion tank designed to absorb excess pressure caused by thermal expansion in closed-loop potable water and hydronic heating systems. Fitted with a fixed diaphragm, the tank separates the system water from the pre-charged air chamber, protecting pipes, valves, and water heaters from overpressure damage. This type of component is typically installed by licensed plumbers and HVAC technicians as part of a code-compliant closed water system.
The ZTTA-12 is suited for residential and light commercial applications where a backflow preventer or pressure-reducing valve creates a closed system. Common install scenarios include domestic hot water systems paired with storage-type water heaters, as well as hydronic heating loops requiring pressure management. Its 5-gallon capacity makes it appropriate for small to mid-sized system volumes.
Designed as an OEM-style replacement or new-installation expansion tank for closed-loop potable water and hydronic heating systems requiring thermal expansion management.
Installation should be performed by a licensed plumber in accordance with local plumbing codes and IPC guidelines. Shut off the water supply and relieve system pressure before installation. Verify the tank pre-charge pressure matches system supply pressure prior to connecting. Do not exceed the rated working pressure of the tank or system.
We pulled together the parts most installs need for this unit, plus a few add-ons worth a look. Check what you need — nothing here blocks checkout.
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