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Manufacturer Resources
Product Specs
- Application:
- Water Heater
- Body Material:
- Lead Free Brass
- Gpm When Relieved:
- Does Not Apply to Product
- Inlet Connection Size:
- 3/4 IN
- Inlet Connection Type:
- Male Threaded
- Inlet Thread Type:
- NPT
- Maximum Temperature:
- 250°F
- Maximum Temperature Fahrenheit:
- 250
- Maximum Working Pressure:
- 15
- Outlet Connection Size:
- Does Not Apply To Product
- Outlet Connection Type:
- Does Not Apply To Product
- Outlet Thread Type:
- Does Not Apply To Product
- Pressure Range:
- Does Not Apply To Product
- Pressure Relief Setting:
- 75 PSI
- Pressure Relief Setting Psi:
- 75
- Pressure Steam Discharge Capacity:
- Does Not Apply to Product
- Protection Type:
- Pressure
- Series:
- LFN36
- Shank Length:
- Does Not Apply To Product
- Temperature Relief:
- 9999°F
- Temperature Relief Fahrenheit:
- 9999
- Temperature Steam Discharge Capacity:
- Does Not Apply to Product
- Test Lever:
- No
- Thermostat Material:
- Does Not Apply To Product
- Thermostat Probe Length:
- Does Not Apply To Product
- Department:
- Plumbing
- Product Group:
- Plumbing
- Product Subgroup:
- Valves
- Product Type:
- Relief Valve
Watts 556031 – Frequently Asked Questions
1) What does the Watts 0556031 vacuum relief valve actually do on a water heater?
The Watts LFN36 series valve is a vacuum breaker for water heater installations. If the supply line drains or loses pressure, a vacuum can form in the tank and siphon water back out, uncovering the elements or burner surface and risking a dry-fire or a back-siphon of tank water into the potable supply. This valve opens to admit air and break that vacuum. It is not a T&P valve and does not replace one; a water heater still needs its own temperature and pressure relief valve.
2) What size and thread does the Watts 0556031 need on the water heater tapping?
It is a 3/4 inch male NPT inlet, so it threads directly into a 3/4 inch female NPT tapping or into the branch of a 3/4 inch tee on the cold inlet line. There is no outlet connection to pipe, the valve vents to atmosphere through the protective cap.
3) Can I use this instead of a T&P relief valve on a water heater?
No. The LFN36 is a vacuum breaker, it admits air to break a siphon, it does not discharge water on overtemperature and it has no thermostat probe. A water heater still needs a separate listed temperature and pressure relief valve with the correct probe length for the tank. Use the 0556031 alongside it, on the cold inlet, not in its place.
4) Is this Watts vacuum relief valve lead free for potable water?
The body is lead free brass, so it suits potable water service on domestic hot water heaters and storage tanks where lead free materials are required.
5) What temperature and pressure can the Watts 0556031 handle?
Rated to 250 degrees F maximum temperature and 15 psi maximum working pressure. That 15 psi figure is the limit for the valve itself, which is why it belongs on a vented or low pressure point of the system, not in place of a relief valve on a pressurized line.
6) Does the Watts 0556031 have a test lever?
No test lever on this one. It is fitted with a protective cap over the air inlet instead, which keeps debris out of the seat between operations. If your inspector or facility standard requires a manually testable relief device, that requirement applies to the T and P valve, not to the vacuum breaker.
7) What is the 75 PSI figure on the Watts 0556031?
75 psi is the listed pressure relief setting for the valve, with protection type given as pressure. It is not a flow-through discharge rating, there is no steam discharge capacity or GPM relieved figure for this device because it vents air rather than water.
8) How do I order the right Watts vacuum relief valve, and what is the part number?
Manufacturer part number 556031, sold as the 0556031 in the LFN36 series. One configuration only, 3/4 inch male NPT with the protective cap, so there is no size or connection option to specify when ordering.
How fast can I get the Watts 556031 delivered?
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Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit,
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Does the Watts 556031 come with a warranty?
Absolutely. The Watts 556031 is backed by a manufacturer’s warranty.
For full warranty terms, check the product documentation or Contact Us.
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