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Brass vacuum relief valve, 3/4 inch MNPT connections, 2 inch height, stainless steel spring

Watts

Watts LFN36-M1 Vacuum Relief Valve 3/4 in MNPT 0 to 200 psi SS

SKU CH-WG4G-HAWM4

Vacuum relief valve for domestic water heaters and supply tanks, factory set at 15 psi with a 0 to 200 psi range

  • TypeOther
  • Protects water heaters from vacuum damage with factory-set 15 psi relief
  • Handles pressure up to 200 psi for reliable system safety
  • Brass body with silicone disc resists corrosion in domestic hot water
  • 302 stainless steel spring ensures consistent operation across 0 to 250 °F
  • Meets ANSI Z21.22 and CSA standards for code-compliant installation

Vacuum Relief for Water Heaters

The Watts LFN36-M1 vacuum relief valve protects domestic water heaters and supply tanks from vacuum damage. It opens at a factory-set pressure of 15 psi and operates across a 0 to 200 psi range. The brass body and silicone disc handle water temperatures up to 250 degrees F. This new component meets ANSI Z 21.22 and CSA standards.

3/4 in MNPT Inline Installation

The valve connects directly into 3/4 in MNPT threaded ports on both inlet and outlet sides. Its compact 2 in height and 2 in length allow fitment in tight plumbing runs without extra fittings. A 302 stainless steel spring provides consistent actuation. No test lever is included, so functional verification requires external means.

Pressure Range and Temperature Headroom

The 0 to 200 psi working range covers typical residential and light commercial supply pressures with ample margin. The 250 degrees F temperature rating suits standard water-heater discharge conditions. Systems requiring a test lever, higher pressure settings, or larger port sizes will need a different valve model.

Highlights

  • Protects water heaters from vacuum damage with factory-set 15 psi relief
  • Handles pressure up to 200 psi for reliable system safety
  • Brass body with silicone disc resists corrosion in domestic hot water
  • 302 stainless steel spring ensures consistent operation across 0 to 250 °F
  • Meets ANSI Z21.22 and CSA standards for code-compliant installation

Specifications

BrandWATTS
TypeOther

Questions about this item

At what factory-set pressure does the LFN36-M1 begin to relieve vacuum?

The valve is factory set to open at 15 psi, protecting domestic water heaters and supply tanks from vacuum conditions.

What are the temperature and pressure limits during continuous operation?

It handles 0 to 250 degrees F and a pressure range of 0 to 200 psi, with a brass body, silicone disc and 302 stainless steel spring.

Which piping connections must already be in place for this 3/4 inch MNPT valve?

You need matching 3/4 inch female NPT threads on both the inlet and outlet sides of your water heater or tank piping.

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