WATTS 840M4 Freeze Pressure Vacuum Breaker Anti Siphon 800M4 3/4

( Brand: Watts ), ( Manufacturer Part Number: 840M4 ), ( Part Type: Pressure Vacuum Breaker )

Review WATTS Fr 3/4 Inch Freeze Resistant Pressure Vacuum Breaker Anti Siphon

The Watts 840M4 and 800M4 **3/4-inch Freeze-Protected Pressure Vacuum Breakers (PVBs)** are premium, code-compliant solutions designed to safeguard plumbing systems from backflow and siphonage while maintaining optimal water pressure and preventing freezing in cold climates. These durable, high-performance devices are engineered to meet or exceed the rigorous standards set by the **American Society of Sanitary Engineering (ASSE) 1013** and **NSF/ANSI 61**, ensuring both safety and reliability for residential, commercial, and municipal applications. The **840M4** features a **freeze-protected design**, incorporating a built-in **thermal insulation sleeve** that protects the internal components from freezing temperatures, making it ideal for outdoor or exposed installations where sub-zero conditions are a concern. Meanwhile, the **800M4** offers a standard, yet equally robust, pressure vacuum breaker without freeze protection, providing a cost-effective alternative for areas with milder climates. Both models utilize a **smooth-bore, brass body** with a **stainless steel diaphragm**, ensuring corrosion resistance, longevity, and consistent performance even under fluctuating water pressures. The **3/4-inch connection size** accommodates a wide range of hose bibs, sprinkler systems, and irrigation setups, making these PVBs versatile for both residential lawn sprinklers and commercial irrigation needs. Their **double-check valve mechanism** prevents backflow contamination by ensuring that water flows in only one direction from the supply line to the outlet while the **vacuum breaker function** prevents siphonage, which could otherwise deplete water pressure and cause system damage. The **easy-to-install design** includes a **standard NPT thread** for secure connection to supply lines, and the **quick-connect or threaded outlet options** allow for flexible hose attachments. Whether installed in a basement, garage, or outdoor setting, these Watts PVBs provide peace of mind by protecting against backflow, freezing, and pressure loss, all while adhering to strict plumbing codes and industry best practices. Built to last with minimal maintenance requirements, they are an essential component for any plumbing system where water safety and reliability are paramount.

### **Pros and Cons of buying a Watts 840M4 (800M4) 3/4" Freeze-Protected Vacuum Breaker/Anti-Siphon Valve**

1. **Freeze Protection** The 840M4 model includes a freeze-protecting feature, which prevents water from freezing and expanding inside the valve during cold weather. This is particularly useful in unheated outdoor applications or areas with freezing temperatures.

2. **Reliable Performance** Watts is a well-established brand in plumbing and irrigation, known for durable and dependable products. The vacuum breaker/anti-siphon valve is designed to prevent backflow while maintaining proper water flow.

3. **Backflow Prevention** The valve meets **NSF/ANSI Standard 61** and **ASSE 1014**, ensuring it effectively prevents contaminated water from siphoning back into the potable water supply, which is critical for health and safety.

4. **Easy Installation** The 3/4" size is standard for many residential and light commercial applications, making it compatible with most plumbing systems. It typically requires minimal tools for installation.

5. **Durable Construction** Made from brass or other corrosion-resistant materials, the valve is built to last under normal operating conditions, reducing the need for frequent replacements.

6. **Low Maintenance** Once installed correctly, these valves require little to no maintenance, as they are designed to operate reliably without frequent adjustments.

7. **Versatile Applications** Suitable for outdoor hoses, sprinkler systems, and other non-potable water applications where backflow protection is necessary.

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1. **Limited Indoor Use** While freeze-protected models like the 840M4 are designed for outdoor or exposed applications, they are not ideal for indoor use where temperatures remain consistently above freezing.

2. **Potential Clogging** If debris enters the valve (e.g., from a hose or irrigation system), it may become clogged, reducing performance. Regular cleaning may be required in some cases.

3. **Cost Compared to Basic Models** The freeze-protected version is more expensive than standard vacuum breakers (e.g., the 800M4 without freeze protection). If freeze protection isn t necessary, a cheaper alternative may suffice.

4. **Pressure Limitations** While it handles typical household water pressures, extremely high pressures (beyond standard municipal ranges) could stress the valve over time, potentially reducing its lifespan.

5. **Replacement Parts Availability** While Watts is reliable, older models may have limited availability for replacement parts compared to newer or more commonly used valves.

6. **Installation Requirements** Must be installed correctly (properly elevated and angled) to function as intended. Improper installation can lead to failure or reduced effectiveness.

7. **Not for High-Flow Systems** If used in high-flow applications (e.g., large irrigation systems), the valve may struggle to keep up, leading to potential backflow risks.

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The **Watts 840M4 (or 800M4 with freeze protection)** is an excellent choice for **outdoor, freeze-prone applications** where backflow prevention is critical. Its durability, compliance with safety standards, and ease of installation make it a strong option for residential and light commercial use. However, if freeze protection isn t necessary, a standard vacuum breaker (like the 800M4 without freeze protection) may be a more cost-effective alternative.

For **indoor use** or **areas without freezing risks**, a simpler valve may be sufficient. If you re in a **cold climate** or need a valve that can withstand freezing temperatures, the 840M4 is a reliable investment.

- You need freeze protection for outdoor hoses, sprinklers, or exposed plumbing.

- You prioritize long-term reliability and compliance with backflow standards.

- Your budget allows for the slightly higher cost of freeze-protected models.

- Freeze protection isn t necessary (e.g., indoor use or mild climates).

- You want to save money while still getting a high-quality backflow prevention valve.

- You need a valve for **high-pressure or high-flow industrial applications** (a different model may be required).

- You re unsure about proper installation and cannot ensure correct setup.

For most **residential outdoor use in cold climates**, the **Watts 840M4 is the best choice** due to its freeze protection and reliability. Always verify local plumbing codes to ensure compliance with backflow prevention requirements.

Details:

Possibly unused. A watts model 800M4 freeze resistant vacuum breaker. Buyer to pay return shipping. No apparent damage.

Expect minor evidence of use or imperfections, dings etc. In overall very good condition in the original box. Shelf B5/051226 - OE.

part #: 840m4 prices

• $119.99-$185.00

specifications valvesplumbing:

• brand: Watts
• mpn: 840m4
• part type: Pressure Vacuum Breaker

shipping valvesplumbing:

• carrier: USPS, FedEx
• transit: 3-6 Days
• class: Standard, Expedited
• service: USPS Ground Advantage, USPS Priority Mail, FedEx Ground / FedEx Home Delivery
• type: Calculated
• cost: $24.05

payments valvesplumbing:

• credit card: Visa
• other
• wallet: Apple-pay

general valvesplumbing:

• Hydraulics, Pneumatics, Pumps Plumbing > Valves Manifolds > Vacuum Breakers
• condition: Used

seller valvesplumbing:

• rating: 100.0%
• # reviews: 22756
• city: Enola, Pennsylvania

offer valvesplumbing:

• availability: In Stock
• quantity: 1
• best offers: True
• options: Ship-to-home
• sold: 0
• started: May 16, 2026

returns valvesplumbing:

• time: 30 Days
• policy: Returns Accepted
• method: Money back
• paid by: Buyer

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