McDonnell & Miller 339900 Valve Assembly and Gaskets

When you are maintaining a Series 25-A make-up water feeder, the McDonnell & Miller 339900 (Model SA25A-6) is the exact float valve assembly required to restore proportional feed action. This technical kit includes both the precision-engineered valve assembly and gaskets, ensuring a positive seal on the soft seat for reliable water level management in boiler receiver tanks. As a veteran-grade replacement part, it is built to withstand a maximum water supply pressure of 100 psi and inlet water temperatures up to 120°F. The integration of high-quality elastomer gaskets prevents leaks between the float chamber and the valve body, maintaining the 35 psi vessel pressure rating essential for commercial hydronic systems. Using the 339900 valve sub-assembly allows for a direct-fit repair, bypassing the need for a full unit replacement and ensuring your 25A series feeder continues to provide an anti-siphon air gap for safe operation.

• Direct Compatibility: Precision-fit for all McDonnell & Miller Series 25-A make-up water feeders.
• Full Seal Kit: Includes the SA25A-6 valve assembly and all necessary replacement gaskets for a leak-free installation.
• High-Pressure Rating: Engineered for systems requiring 100 psi maximum supply pressure and 120°F inlet temperatures.
• Proportional Feed: Maintains consistent boiler water levels mechanically, independent of electrical power.

Will this valve assembly work with older 25A models?
Yes, the 339900 is the standard valve replacement part for the 25A series. If your current unit uses a float-operated mechanism for a receiver tank, this sub-assembly is the correct technical specification for a rebuild.

What is included in the SA25A-6 kit?
The kit contains the complete internal valve mechanism (stem, disc, and seat) and the critical gaskets required to seal the valve housing to the float chamber. It does not include the float ball or the external cast iron bowl.

Can I use this for high-temperature condensate return?
This assembly is rated for a maximum inlet temperature of 120°F. For systems exceeding these thermal limits, verify your supply line temperature to avoid premature wear on the soft seat seal.

This item is not eligible for free shipping.

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.