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Manufacturer Resources
Product Specs
- Application:
- Boiler
- Body Material:
- Bronze
- Country Of Origin:
- United States
- Inlet Connection Size:
- 1 IN
- Inlet Connection Type:
- Female Threaded
- Inlet Thread Type:
- NPT
- Maximum Temperature:
- 250°F
- Maximum Working Pressure:
- 20
- Outlet Connection Size:
- 1 IN
- Outlet Connection Type:
- Female Threaded
- Outlet Thread Type:
- NPT
- Pressure Range:
- 30 to 150 PSI
- Pressure Relief Setting:
- 30 PSI
- Pressure Steam Discharge Capacity:
- 1,005,000 BTU per hour
- Protection Type:
- Pressure
- Series:
- 174A
- Test Lever:
- Yes
- Department:
- Plumbing
- Product Group:
- Plumbing
- Product Subgroup:
- Valves
- Product Type:
- Relief Valve
Watts 274934 – Frequently Asked Questions
1) What pressure does the Watts 174A 0274934 relief valve open at?
It's factory set to relieve at 30 psi. That's the standard setting for a residential or light commercial hot water heating boiler, where the system operating pressure typically sits well below it. The 174A series as a whole covers settings from 30 to 150 psi, so if your boiler is tagged for a higher MAWP you'd order a different setting in the same series rather than this one.
2) What size and type are the connections on this Watts boiler relief valve?
Both ends are 1 inch female NPT, inlet and outlet. So it threads onto a 1 inch male NPT nipple off the boiler tapping, and the discharge side takes a 1 inch male NPT fitting for your drain line. No adapters needed if your tapping is 1 inch.
3) Can I use this valve on a water heater instead of a boiler?
No. The Watts 174A 0274934 is a pressure-only relief valve for boiler service. It protects against overpressure and has no temperature relief element, so it will not satisfy the T and P requirement on a domestic water heater. For a water heater you need a combination temperature and pressure relief valve. Use this one on a hot water heating boiler where a separate pressure relief device is what the system calls for.
4) Will this relief valve handle the output of my boiler?
Its rated steam discharge capacity is 1,005,000 BTU per hour. Match that against the boiler's input rating on the nameplate: the relief valve capacity has to equal or exceed it. For most residential and small commercial hot water boilers, a million BTU of capacity is well clear. If your unit is rated above that, size up.
5) What is the maximum temperature this Watts bronze relief valve can see?
250 degrees F is the maximum. That covers normal hot water heating boiler operation with room to spare, since a hydronic system typically runs in the 180 range. The body is bronze, which is why it holds up in continuous hot water service.
6) Does this Watts relief valve have a test lever for annual maintenance?
Yes, it has a test lever. That lets a maintenance tech manually lift the disc to verify the valve is free and not seized with scale, which is the standard annual check on a boiler relief valve. Useful if you're standardizing relief valves across a building and want one that can be exercised without pulling it.
7) Can I plug or valve off the discharge outlet of a boiler relief valve?
Never. The 1 inch female NPT outlet on the Watts 174A has to run to a full-size, unobstructed discharge line terminating near the floor, with no shutoff, reducer, or cap anywhere in it. Any restriction defeats the 1,005,000 BTU per hour discharge capacity the valve is rated for and leaves the boiler unprotected.
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reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Watts 274934 come with a warranty?
Absolutely. The Watts 274934 is backed by a manufacturer’s warranty.
For full warranty terms, check the product documentation or Contact Us.
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