Watts 11/4 AS-M1 T Air Separator Cast Iron 275F 80 psi

Watts 11/4 AS-M1 T Air Separator

This Watts air separator is built for hydronic heating and cooling systems that need continuous air removal. It suits mechanical contractors and facility engineers who specify cast iron components for commercial boiler loops. The unit handles water media in closed-loop piping where trapped air reduces heat transfer and causes noise.

In-line NPT connections simplify piping

The separator installs in-line with 1 1/4 inch female NPT inlet and outlet ports so it fits standard iron pipe threads without adapters. A 1 1/4 inch female NPT air vent connection and a 1/2 inch female NPT expansion tank port are integrated into the body. Cast iron construction resists mechanical damage but requires proper thread sealant and support to prevent stress on the joints during thermal cycling.

Rated 275F and 80 psi for water

The cast iron body is rated for a maximum operating temperature of 275F and a working pressure of 80 psi with water as the heat-transfer fluid. These limits define the envelope for boiler-loop installations; systems that exceed either value need a different separator material or pressure class. The included expansion tank connection allows direct mounting of a diaphragm tank without extra fittings.