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Manufacturer Resources
Product Specs
- Application:
- Boiler
- Body Material:
- Iron
- 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 1/4 IN
- Outlet Connection Type:
- Female Threaded
- Outlet Thread Type:
- NPT
- Pressure Range:
- 30 to 75 PSI
- Pressure Relief Setting:
- 30 PSI
- Pressure Steam Discharge Capacity:
- 1,300,000 BTU per hour
- Protection Type:
- Pressure
- Series:
- 740
- Test Lever:
- Yes
- Department:
- Plumbing
- Product Group:
- Plumbing
- Product Subgroup:
- Valves
- Product Type:
- Relief Valve
Watts 382570 – Frequently Asked Questions
1) What size pipe does the Watts 740 model 382570 boiler relief valve thread into?
The inlet is 1 inch female NPT and the outlet is an expanded 1-1/4 inch female NPT. That means it threads directly onto a 1 inch NPT tapping on the boiler, and the discharge piping run off the outlet has to be 1-1/4 inch, not 1 inch. Never reduce the discharge line below the outlet size.
2) Is the Watts 382570 relief valve for a hot water boiler or a steam boiler?
It's a pressure-only relief valve for a boiler application, set at 30 psi, with a steam discharge capacity of 1,300,000 BTU per hour. Protection is pressure only, so it is not a combination temperature and pressure (T&P) valve of the kind used on a water heater.
3) My boiler runs at about 20 psi. Will a 30 psi relief valve work?
Yes. The 382570 is set to relieve at 30 psi and carries a 20 psi maximum working pressure, so a system operating at 20 psi sits below the relief point with margin. If your boiler operates above 20 psi, this is the wrong setting and you want a higher-set valve out of the 740 series, which covers 30 to 75 psi.
4) Will the 1,300,000 BTU capacity on this Watts relief valve cover my boiler?
The 382570 has a pressure steam discharge capacity of 1,300,000 BTU per hour. The relief valve's rated capacity has to equal or exceed the gross output of the boiler it protects, so check your boiler nameplate output against that figure. If your boiler output is higher, this valve is undersized for the job.
5) Does this Watts boiler relief valve have a manual test lever?
It does. The 382570 includes a test lever so a maintenance tech can manually lift the disc to verify the valve is free and not stuck from scale or mineral buildup. That matters for anyone on a scheduled boiler PM route, since periodic manual testing is the normal way of proving the valve still operates.
6) What is the maximum temperature the Watts 740 382570 relief valve can handle?
250 degrees F is the maximum temperature. The body is iron, and it's a pressure relief valve, so it protects against overpressure rather than tripping on temperature.
7) What does "expanded outlet" mean on this Watts 740 relief valve?
It means the discharge side is larger than the inlet: 1 inch female NPT in, 1-1/4 inch female NPT out. The bigger outlet keeps back pressure down when the valve blows, so it can pass its full rated flow. Practically, you need a 1-1/4 inch fitting and drain line at the valve rather than matching the 1 inch supply thread.
How fast can I get the Watts 382570 delivered?
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Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit,
reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Watts 382570 come with a warranty?
Absolutely. The Watts 382570 is backed by a manufacturer’s warranty.
For full warranty terms, check the product documentation or Contact Us.
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