Watts 0066606 Expansion Tank

The Watts 0066606 (Model ETX-30) is a high-performance hydronic expansion tank designed specifically for closed-loop heating and cooling systems. As a veteran-grade direct replacement for 0067411 and the legacy ETX-30 series, this 4.5-gallon unit effectively manages thermal expansion by absorbing excess water volume to protect the boiler and system piping. Built with a rugged carbon steel shell and an epoxy finish, it features a heavy-duty butyl diaphragm that keeps system water separated from the air charge, preventing waterlogging and localized corrosion. Pre-charged at 12 PSI via a standard Schrader valve, the tank supports a maximum working pressure of 75 PSI and temperatures up to 220°F. The 1/2" MNPT system connection ensures a standard in-line installation for residential or light commercial service. This non-potable unit is compatible with glycol, ensuring reliable HVAC system pressure control for modern hydronic configurations.

• System Protection: Minimizes pressure spikes to prevent the relief valve from nuisance tripping.
• Field Serviceability: Features an accessible tire-style air valve for easy pre-charge adjustments based on static system pressure.
• Durable Barrier: The butyl rubber diaphragm eliminates air-to-water contact, maintaining the nitrogen or air cushion without frequent venting.
• Compact Footprint: Designed for an in-line mount directly to supply piping, saving space in tight mechanical rooms.
• Broad Compatibility: Fully suitable for use with water or water-glycol mixtures in radiant and baseboard loops.

Is the ETX-30 suitable for domestic hot water systems?
No, the 0066606 is a non-potable expansion tank. It is designed strictly for closed-loop hydronic heating; using it in potable water systems violates plumbing codes and can lead to contamination.

Can I mount this tank horizontally?
Yes, the Watts ETX series can be installed in either a vertical or horizontal orientation. However, when mounting horizontally, ensure the piping is adequately supported to prevent stress on the 1/2" connection due to the weight of the water-filled tank.

What is the correct pre-charge setting for this tank?
While factory pre-charged to 12 PSI, for optimal performance, you should adjust the air pressure to match your boiler fill valve setting (typically 12–15 PSI) while the tank is empty or isolated from system pressure.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.