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Manufacturer Resources
Product Specs
- Application:
- Boiler
- Body Material:
- Iron
- Gpm When Relieved:
- Does Not Apply To Product
- Inlet Connection Size:
- 1 IN
- Inlet Connection Type:
- Female Threaded
- Inlet Thread Type:
- NPT
- Maximum Temperature:
- 250°F
- Maximum Temperature Fahrenheit:
- 250
- Maximum Working Pressure:
- 56
- 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:
- 75 PSI
- Pressure Relief Setting Psi:
- 75
- Pressure Steam Discharge Capacity:
- 2,649,000 BTU per hour
- Protection Type:
- Pressure
- Series:
- 740
- Shank Length:
- Does Not Apply To Product
- Temperature Steam Discharge Capacity:
- Does Not Apply To Product
- Test Lever:
- Yes
- 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 382821 – Frequently Asked Questions
1) What size pipe does the Watts 740 Series 0382821 relief valve thread into?
The inlet is 1 inch female NPT and the outlet is 1-1/4 inch female NPT. That expanded outlet is intentional: the discharge line has to be at least as large as the valve outlet, so you'll run 1-1/4 inch pipe down to within a few inches of the floor. Don't reduce it back to 1 inch on the discharge side.
2) Does this Watts boiler relief valve protect against temperature, or pressure only?
Pressure only. The 0382821 is a straight pressure relief valve with no thermostat probe, so it responds to system pressure and not to water temperature. If you need combined temperature and pressure protection, such as on a water heater, you need a T and P valve with a probe instead.
3) How much BTU capacity will this 75 psi Watts relief valve handle?
Steam discharge capacity is 2,649,000 BTU per hour. Match that against the boiler's gross input rating on the nameplate: the valve's rated capacity has to equal or exceed the boiler input, otherwise the boiler can outrun the valve. On a boiler larger than that figure, you need a bigger valve or multiple valves.
4) Does the Watts 0382821 come with a test lever so I can do annual testing?
Yes, it has a manual test lever. Lifting it once a year under pressure is the standard maintenance check to confirm the seat is not stuck or limed up. Do the test with the discharge line piped and directed safely, since it will dump hot water.
5) Can I install this Watts relief valve on a water heater or a potable line?
No. The 0382821 is built for boiler service, with an iron body and a pressure-only relief function. Water heaters need a temperature and pressure valve with a thermostat probe in the tank, and potable applications call for a bronze or lead-free body rather than iron.
6) Where in the 30 to 75 psi Watts 740 range does this particular model fall?
The 740 Series is offered across a 30 to 75 psi range, and the 0382821 is the top of it at 75 psi, fixed. Relief settings are not field adjustable, so if the boiler needs 30 psi protection you order the 30 psi version rather than trying to reset this one.
7) Can I install this relief valve with a shutoff valve between it and the boiler?
No. This valve threads directly into the boiler tapping with nothing between it, no shutoff, no reducing bushing, no tee. The 1 inch female NPT inlet is sized to land on the boiler's relief tapping, and the valve must be mounted upright, vertical, with the outlet piped to a safe discharge point.
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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 382821 come with a warranty?
Absolutely. The Watts 382821 is backed by a manufacturer’s warranty.
For full warranty terms, check the product documentation or Contact Us.
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