The Watts Regulator Co. 100XL4 100XL 4 3/4 150-210 relief valvef is a trusted safety device for hot water systems. This temperature and pressure relief valve (often called a T&P valve) protects water heaters and storage tanks from dangerous buildup of pressure or heat. Made by Watts, a leader in plumbing products since 1874, this model features a 3/4-inch size, 150 psi pressure relief, and 210°F temperature relief. Professionals and experienced homeowners rely on it to meet safety codes and prevent accidents in homes, apartments, and commercial buildings.
Why Choose the Watts Regulator Co. 100XL4 100XL 4 3/4 150-210 Relief Valvef?
Plumbers and HVAC technicians often pick this Watts 100XL relief valve because it works well and lasts long. Watts has made quality valves for over 140 years. This model belongs to the 100XL series, known for protecting systems up to 105,000 BTU/hr.
Key benefits include:
- Automatic protection against too much pressure or heat.
- Brass body that resists rust.
- Self-closing design for safety.
- Test lever to check if it works.
This Watts temperature and pressure relief valve meets important codes like ASME, CSA, and ANSI Z21.22. Building rules require a water heater safety valve like this on every tank.
Detailed Specifications of the Watts 100XL4 Valve 3/4 Inch
The Watts Regulator Co. 100XL4 100XL 4 3/4 150-210 relief valvef (also listed as 100XL-150 3/4 or similar) has these main specs:
- Size: 3/4 inch NPT male inlet, NPT female outlet.
- Pressure Relief: Set at 150 psi (opens to release extra pressure).
- Temperature Relief: Set at 210°F (99°C).
- Materials: Brass body, stainless steel spring, nylon-coated copper thermostat with 4-inch probe.
- Features: Extension thermostat, test lever, self-closing.
- Capacity: Suitable for water heaters up to 105,000 BTU/hr.
- Certifications: ASME rated, CSA listed.
The “4” in 100XL 4 3/4 often means a 4-inch thermostat probe for better sensing in insulated tanks. This helps in modern water heaters with thick insulation.
Watts 0066100 100XL 3/4″ Temperature and Pressure Relief Valve | Ferguson Home
How the Watts Pressure Relief Valve 150 Psi Works
A temperature pressure relief valve has two jobs:
- If pressure goes over 150 psi, it opens to let water out.
- If temperature hits 210°F, the thermostat expands and opens the valve.
This stops tanks from exploding – a rare but serious risk. The valve drips a little sometimes, but constant leaking means it needs replacement.
This Watts safety relief valve 210°F is a plumbing pressure relief valve that also handles heat. It fits most residential and light commercial hot water tanks.
Installation Guide for the Watts 100XL4 Valve 3/4 Inch
Professional plumbers should install or replace these valves, but here are the basic steps for understanding:
- Turn off power/gas to the water heater and close the cold water inlet.
- Drain some water to lower pressure.
- Unscrew the old valve (use pipe wrench, have a bucket ready for water).
- Apply Teflon tape to new valve threads.
- Screw in the Watts 3/4 inch pressure and temperature valve hand-tight, then 1/4 turn more.
- Attach discharge pipe (must go to safe drain, no threads on end).
- Turn water on, check for leaks, test lever.
Tip: The probe must go fully into the tank for correct temperature reading.
For full instructions, see the official Watts 100XL product page.
How to Fix Replace Water Heater Broken T&P Valve – Watts 100XL to …
Common Uses and Compatibility
This Watts water heater relief valve works with:
- Electric and gas water heaters.
- Hot water storage tanks.
- Systems needing a 3/4″ Watts pressure relief valve.
It replaces older Watts 100XL replacement valve models directly. Many brands like Rheem or AO Smith specify Watts T&P valves.
In commercial buildings, facility managers use these for hot water system safety valve compliance.
When to Replace Your Watts T&P Valve 150 Psi 210 F
Replace every 3-5 years or if:
- It leaks constantly.
- The test lever doesn’t work.
- The water heater is over 5 years old.
- You see rust or damage.
A bad hot water tank relief valve can cause floods or failures. Testing yearly lifts the lever to check flow.
Buying the Watts Regulator Co. 100XL4 100XL 4 3/4 150-210 Relief Valvef
Look for this Watts brass relief valve 3/4″ at plumbing suppliers, online, or stores like Walmart. Check listings for Watts pressure relief valveshe1re.
Prices range $20-40. Buy from trusted sellers for genuine parts.
For exact matches, search where to buy Watts 100XL4 relief valve or check Watts distributors.
Safety Statistics and Why It Matters
Water heater failures cause thousands of injuries yearly in the US. Proper pressure and temperature valve like this Watts regulator temperature relief valve prevent most.
ASME codes require T&P valves on all new installations. This safety valve for water heaters saves lives and property.
Tips for Professionals and DIYers
- Always match specs: Watts 100XL 150 psi relief valve for standard homes.
- Use lead-free versions (LF100XL) if needed for drinking water.
- Pipe discharge to floor drain or outside, 6 inches above ground.
- Don’t cap or plug the valve – it’s illegal and dangerous.
Experienced DIY homeowners can replace, but call a pro if unsure.
Alternatives and Related Products
Other Watts regulator co valve 100XL4 options include longer shanks (like LL100XL for thick insulation) or different pressures.
Similar: Cash Acme or Apollo valves, but Watts is top for reliability.
In Conclusion: Trust the Watts Regulator Co. 100XL4 100XL 4 3/4 150-210 Relief Valvef for Peace of Mind
The Watts Regulator Co. 100XL4 100XL 4 3/4 150-210 relief valvef stands out as a dependable Watts T&P valve 150 psi 210 F. It offers strong protection with brass build, easy testing, and code approval. Plumbers, maintenance pros, and careful homeowners choose it for safe hot water systems. Install the right water heater temperature pressure valve Watts to avoid risks and follow rules.
Have you replaced a T&P valve recently? What tips would you share with others?
Frequently Asked Questions About Watts Regulator Co. 100XL4 100XL 4 3/4 150-210 Relief Valvef
What is the Watts 100XL-4 relief valve used for?
This valve protects your water heater or hot water storage tank from too much pressure or heat. It opens automatically if the temperature reaches 210°F or the pressure hits 150 PSI. It works on water heaters up to 105,000 BTU/hr. It is a required safety device in most homes.
What are the main specifications of the Watts 100XL-4?
- Size: 3/4 inch
- Inlet: Male NPT (threaded)
- Outlet: Female NPT
- Pressure setting: 150 PSI
- Temperature setting: 210°F
- Body material: Bronze (strong and resists rust)
- Features: Test lever, 4-inch extension thermostat (probe)
- Certifications: ASME rated, CSA listed It closes by itself after opening.
How do I install the Watts 100XL-4 relief valve?
Turn off the water and power/gas to the heater first. Drain some water to reduce pressure. Unscrew the old valve. Apply pipe tape to the threads of the new valve. Screw it in hand-tight, then use a wrench for 1/4 turn more. Do not over-tighten. Attach a discharge pipe to the outlet that goes down to a safe drain. Always follow local plumbing codes.
Where should the discharge pipe go?
The pipe must end 6 inches above a floor drain or outside. It should point down and not have threads on the end. This lets hot water safely flow out if the valve opens.
How often should I test the Watts 100XL-4 valve?
Lift the test lever once a year to check if it works. Water should come out, and the lever should snap back. If it leaks after testing or does not open, replace the valve right away.
Why is my Watts 100XL-4 leaking or dripping water?
A small drip after testing is normal, but constant leaking means the valve is bad. It could be from high pressure in your home, sediment buildup, or the valve is old (they last 3-5 years). Check your water pressure – it should be under 80 PSI. Replace the valve if it keeps leaking.
How long does this relief valve last?
Most last 3 to 5 years. Check it every year. Replace it if it leaks, fails the test, or is over 5 years old. Many codes say to replace every 5 years.
Can I use this valve on any water heater?
Yes, it fits most residential water heaters with a 3/4-inch tapping. It works for gas, electric, and tankless up to 105,000 BTU/hr. Always match the pressure (150 PSI) and temperature (210°F) to your heater’s needs.
Reference
- Official Watts Product Page (accessed December 2025): Specifications for 100XL-150 3/4, including ASME/CSA certifications, materials, and applications for hot water tanks up to 105,000 BTU/hr. Targeted at professional plumbers and facility managers for compliance and installation. ↩︎