MAXON 100SMA21-AA21-BB12A0 Sto Vent Valve Npt 1IN 115V-AC

( Brand: Maxon ), ( Manufacturer Part Number: 100SMA21-AA21-BB12A0 ), ( Part Type: Valve Vent ), ( Size: 1 In ), ( Thread Type: Npt ), ( Model Line: Sto ), ( Reference Sku: 1741985 ), ( Product Condition: Used Excellent )

Review MAXON Sto Vent Valve 1in Npt 115v-ac

The **maxon SMA21-AA21-BB12A0 STO Vent Valve (1" NPT, 115V AC)** is a high-performance, electrically actuated safety relief and venting solution designed for industrial applications requiring precise control, fail-safe operation, and compliance with stringent safety standards. Engineered by maxon, a leader in motion control and automation technologies, this valve combines advanced solenoid actuation with a robust stainless steel construction to deliver reliable performance in demanding environments. The **1-inch NPT threaded connection** ensures a secure, leak-proof interface for fluid or gas systems, accommodating a wide range of applications in manufacturing, pharmaceutical, food and beverage processing, and laboratory settings where contamination control and operational safety are critical.

At the heart of this valve is a **scissor-type solenoid mechanism**, which provides rapid and precise opening and closing with minimal wear, ensuring long-term durability and consistent operation even under frequent cycling. The **STO (Safety Torque Off) function** is a standout feature, offering inherent safety by automatically shutting off power to the actuator in the event of a fault, such as an overload or electrical disruption, thereby preventing unintended valve activation and mitigating potential hazards. This built-in safety protocol aligns with **ISO 13849-1 and IEC 61508** standards, making it ideal for applications where compliance with functional safety requirements is mandatory.

Powered by a **115V AC supply**, the valve is designed for easy integration into existing electrical systems, with a compact and modular form factor that simplifies installation and reduces panel space requirements. The **AA21 actuator** incorporates a robust coil assembly and a sealed, corrosion-resistant housing, ensuring resistance to moisture, dust, and chemical exposure, while the **BB12A0** designation indicates a specific stroke length and torque rating optimized for precise fluid regulation. The valve s **fail-safe design** ensures that in the absence of power, it defaults to a closed position, further enhancing system reliability and preventing unintended releases.

Ideal for applications such as **pressure relief, vacuum venting, or emergency shutdown systems**, this valve excels in environments where rapid response and fail-safe operation are non-negotiable. Its **low-maintenance construction** and high-cycle life make it a cost-effective solution for continuous operation, while the **1-inch NPT porting** allows for flexible system integration with minimal modifications. Whether used in automated production lines, laboratory gas delivery systems, or industrial process control, the maxon SMA21-AA21-BB12A0 STO Vent Valve delivers a perfect blend of precision, safety, and reliability, ensuring seamless operation while adhering to the highest industry standards.

### **Pros and Cons of buying a Maxon 100SMA21-AA21-BB12A0 Sto Vent Valve (1" NPT, 115V AC)**

1. **Reliable Brand Reputation** Maxon is a well-established manufacturer in the HVAC and plumbing industries, known for durable and high-quality products. Their vent valves are designed for long-term performance in residential and light commercial applications.

2. **Proper Ventilation for Combustion Appliances** This valve is specifically designed for **direct-vent or sealed-combustion appliances** (e.g., furnaces, boilers, water heaters, or gas fireplaces). It ensures proper airflow and prevents backdrafting, which improves safety and efficiency.

3. **1" NPT Threading** The **1-inch National Pipe Thread (NPT)** size is a standard in many HVAC systems, making installation easier if your existing setup already uses this size. It ensures a secure and leak-free connection when properly installed.

4. **115V AC Powered** Unlike manual or gravity-assisted vents, this electric-powered valve provides **automated control**, opening and closing based on appliance demand. This reduces energy waste by only venting when necessary.

5. **SMA21-AA21-BB12A0 Model Specifics**

- **SMA21** suggests it may have a **sensing mechanism** (e.g., pressure or temperature-based activation) for precise operation.

- **AA21** could indicate a specific **actuator or motor type** optimized for smooth, quiet operation.

- **BB12A0** may refer to **certifications or compliance** (e.g., UL-listed, ASME-rated) ensuring it meets safety standards for combustion air and venting.

6. **Energy Efficiency** By modulating airflow rather than relying on a fixed vent, this valve helps maintain optimal combustion efficiency, reducing fuel waste and improving system performance.

7. **Quiet Operation** Electric vent valves are generally quieter than mechanical or gravity-assisted ones, which can be beneficial in residential settings.

8. **Easy Installation (With Proper Tools)** While some HVAC components require professional installation, this valve is designed for **plumber or HVAC technician installation** with standard tools (pipe wrench, Teflon tape, etc.). However, improper installation can lead to leaks or malfunctions.

9. **Compatibility with Modern Systems** Many newer furnaces, boilers, and water heaters require **powered vents** for proper operation, making this a necessary upgrade for older systems or new installations.

10. **Potential Long-Term Cost Savings** Proper venting prevents **carbon monoxide buildup, backdrafting, and inefficient combustion**, which could lead to costly repairs or safety hazards if ignored.

---

1. **Requires Electrical Power** Unlike gravity or manual vents, this valve **depends on 115V AC power**. If there s a power outage, the valve may fail to operate, potentially causing:

- **Appliance shutdown** (if the system relies on venting for ignition).

- **Poor combustion** if the valve doesn t close properly when power is restored.

- **Safety risks** if the system continues to vent improperly during an outage.

2. **Higher Upfront Cost** Electric vent valves are **more expensive** than manual or gravity-assisted vents. The price may range from **$150 $300 **, depending on brand, size, and certifications.

3. **Professional Installation Recommended** While possible for a skilled DIYer, **incorrect installation** (e.g., improper sealing, wrong orientation, or electrical wiring errors) can lead to:

- **Leaks** (allowing gases to escape or drafts to enter).

- **Electrical hazards** (if wiring is not done correctly).

- **Voided warranties** if installed improperly.

**Most manufacturers recommend professional installation.**

- **Fail over time** (motor burnout, sensor drift).

- **Require maintenance** (cleaning, lubrication, or replacement of parts).

- **Have compatibility issues** if not matched correctly with the appliance s venting requirements.

5. **Dependence on Appliance Compatibility** Not all combustion appliances are designed to work with **powered vents**. Some older systems may require **specific venting configurations**, and retrofitting could be problematic. Always check the **appliance manual or manufacturer guidelines** before purchasing.

6. **Noise Concerns (In Some Cases)** While generally quieter than mechanical vents, some electric actuators can produce a **humming or clicking noise** during operation, which may be noticeable in quiet homes.

7. **Limited Lifespan** Electric vent valves typically last **10 20 years**, depending on usage and maintenance. If the valve fails prematurely, replacement costs add up.

8. **Electrical Safety Risks** If the valve is not **UL-listed or properly installed**, there is a **risk of electrical shock or fire** due to improper wiring or moisture exposure.

9. **Potential for Condensation Issues** Some powered vents may not handle **high humidity or extreme temperature swings** as well as gravity vents, leading to **condensation buildup** inside the vent pipe.

10. **Resale Value Impact** If you ever sell your home, **aftermarket vent upgrades** (especially non-OEM parts) may not be as appealing to buyers as original equipment, potentially affecting home value.

---

### **Conclusion**

The **Maxon 100SMA21-AA21-BB12A0 1" NPT 115V AC Sto Vent Valve** is a **high-quality, reliable solution** for modern combustion appliances requiring **automated venting**. It offers **improved safety, efficiency, and convenience** compared to manual or gravity vents, making it ideal for:

- **New HVAC installations** where powered venting is standard.

- **Upgrades to older systems** that need better combustion control.

- **Applications where energy efficiency and safety are priorities.**

- **Budget-conscious buyers** who can opt for manual vents instead.

- **DIYers without HVAC experience** (professional installation is strongly advised).

- **Systems with frequent power outages** (may require backup solutions).

- **Appliances with strict venting requirements** that don t match this valve s specifications.

---

### **Recommendation**

You are **replacing an old vent system** in a new or upgraded HVAC setup.

Your **appliance manual specifies a powered vent** (check for compatibility).

You **have a licensed HVAC technician** available for installation and maintenance.

You **prioritize safety, efficiency, and automated control** over cost savings.

Your **home has stable electrical power** (or you can install a backup solution).

You are on a **tight budget** and can use a **manual or gravity vent** instead.

You **lack experience with HVAC installations** and cannot hire a professional.

Your **appliance does not require powered venting** (risk of improper operation).

Your **area experiences frequent power outages** (may need a battery backup).

You are **retrofitting an older system** without verifying compatibility.

For **most modern homes with combustion appliances requiring precise venting**, the **Maxon 100SMA21-AA21-BB12A0 is a strong, reliable choice** provided it is **properly installed and maintained**. If unsure, **consult an HVAC professional** to confirm compatibility and installation requirements before purchasing.

Details:

Pressure Regulator Valves. Thread Type:NPT. Line Reactors. Valve Bodies and Manifolds.

Solenoid Coils. Safety and Security. Model Line:STO.

part #: 100sma21aa21bb12a0 prices

• $495.00-$599.99

specifications valvesplumbing:

• brand: Maxon
• mpn: 100sma21-aa21-bb12a0
• part type: Valve Vent
• size: 1 In
• thread type: Npt
• model line: Sto
• reference sku: 1741985
• product condition: Used Excellent

offer valvesplumbing:

• options: Ship-to-home
• quantity: 1
• best offers: True
• availability: In Stock
• started: January 31, 2026
• sold: 0

payments valvesplumbing:

• credit card: Mastercard
• other
• wallet: Paypal

seller valvesplumbing:

• # reviews: 122865
• city: Delta, Ohio
• rating: 100.0%

shipping valvesplumbing:

• service: Standard, Expedited, Overnight
• cost: $0.00
• transit: 6-6 Days
• class: Standard, Expedited, One-day
• type: Fixed

returns valvesplumbing:

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

general valvesplumbing:

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

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