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Brass automatic air vent valve with 3/4 inch male NPT bottom inlet

Watts

Watts FV-4M1 3/4 Automatic Air Vent Valve Brass

SKU CH-AWMT-7TPX6

Automatic brass air vent removes trapped air from water systems via a 3/4-inch male NPT bottom inlet

  • Automatically removes trapped air from water systems
  • Brass body and cap resist corrosion in plumbing installations
  • Polyethylene float ensures reliable operation with water media
  • 3/4 inch male NPT inlet connects directly to piping
  • One-port configuration simplifies installation in expansion tank applications

Automatic Air Vent Valve

The Watts FV-4M1 is a brass automatic air vent valve designed for hydronic heating and plumbing systems. It automatically releases trapped air from water circuits to maintain efficient operation. The unit features a 3/4 inch male NPT inlet connection located at the bottom for direct installation. It is intended for use with water media in residential or commercial applications.

Brass Construction and Float

The valve body and cap are constructed from brass for corrosion resistance and durability in water systems. A polyethylene float operates the venting mechanism without requiring external power or manual adjustment. The configuration includes a single port with an expansion tank connection port, though the expansion tank connection itself is not included. These materials suit continuous contact with potable or hydronic water.

Air Removal Capacity

This air vent handles air removal in closed-loop hydronic systems where automatic venting is required. The 3/4 inch NPT inlet provides standard compatibility with common piping sizes for this valve type. It is not suited for applications requiring larger connection sizes, different thread standards, or media other than water. The single-port design limits use to one installation point per unit.

How it compares

Measured against everything we stock in Faucet Valves & Replacement Parts, at today’s prices. Recalculated every night.

Price $37.99
Cheaper than about 65% of the 1,132 comparable items (median $54.99).

Specifications

Product
Brand nameWATTS
Product typeOther

Questions about this item

Will the polyethylene float need replacement over time?

The float is made of polyethylene, a material chosen for durability in water applications; its service life depends on water chemistry and temperature conditions.

What limits continuous air-venting performance?

The single-port, bottom-inlet design vents air until system pressure balances; sustained high flow rates may exceed the port's capacity.

Does the brass body run hot or add noise during all-day operation?

The valve body is brass and handles water at system temperature; it has no moving parts that generate noise under normal venting conditions.

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