HONEYWELL 900C51-0021 Plc Modules

( Brand: Honeywell ), ( Manufacturer Part Number: 900C51-0021 ), ( Part Type: Module )

Review HONEYWELL 900c510021 Used

The **Honeywell 900C51-0021 (or 900C510021)** is a high-performance, multi-stage, variable-speed air conditioning and heating system designed to deliver exceptional comfort, energy efficiency, and reliability for residential and light commercial spaces. Part of Honeywell s advanced **Total Comfort Series**, this model features a **900 Series** inverter-driven compressor, which ensures smooth, precise temperature control by adjusting motor speed in real time rather than cycling on and off. This innovation not only enhances comfort by eliminating temperature fluctuations but also significantly reduces energy consumption, making it an eco-friendly choice for modern homes. The system is engineered with a **copper tube heat exchanger** and **high-efficiency scroll compressor**, which work together to provide superior heat transfer and durability, even in demanding climates. Its **variable-capacity operation** allows the unit to scale its output based on actual demand, further optimizing performance and lowering utility costs over time.

This air conditioning and heating system is built with **R-410A refrigerant**, a standard in modern HVAC technology that offers excellent thermodynamic properties for efficient cooling and heating cycles. The **900C51-0021** is equipped with Honeywell s **Smart Comfort Technology**, which integrates seamlessly with programmable thermostats and smart home systems, enabling remote control via compatible devices for enhanced convenience. The unit s **quiet operation** is another standout feature, thanks to advanced sound-dampening technology that minimizes noise output, making it ideal for bedrooms, living rooms, or any space where tranquility is a priority. Additionally, its **durable construction** includes a **galvanized steel cabinet** and corrosion-resistant components, ensuring longevity and resistance to environmental wear.

For homeowners seeking both performance and sustainability, the **900C51-0021** delivers with its **high SEER (Seasonal Energy Efficiency Ratio) rating**, which maximizes cooling efficiency while minimizing operational costs. The system s **multi-stage operation** allows for fine-tuned climate control, adapting to varying indoor and outdoor conditions with precision. Whether used in a single-zone application or as part of a larger HVAC setup, this model is engineered to provide consistent, reliable performance year-round. With Honeywell s reputation for innovation and quality, the **900C51-0021** stands as a robust, efficient, and user-friendly solution for those looking to upgrade their indoor comfort with cutting-edge technology.

### **Honeywell 900C51-0021 (900C510021) Thermostat: Pros and Cons**

1. **Compatibility with Smart Home Ecosystems** Works seamlessly with **Honeywell Total Connect Comfort (TCC)**, allowing remote control via smartphone, tablet, or computer. It integrates with **Amazon Alexa, Google Assistant, and Apple HomeKit**, making it ideal for users who want voice control and automation.

2. **Energy Efficiency Features** Includes **auto-changeover** for dual-stage heating/cooling systems, **adaptive recovery** to adjust for temperature changes, and **scheduling** to optimize energy use. This can lead to lower utility bills over time.

3. **User-Friendly Interface** Features a **large, backlit display** with intuitive navigation, making it easy to set temperatures, adjust schedules, and monitor system status. The touchscreen is responsive and straightforward for most users.

4. **Compatibility with Multiple HVAC Systems** Supports **heat pumps, furnaces, and air conditioners**, making it versatile for a wide range of residential heating and cooling setups.

5. **Local and Remote Control** Allows manual override from the thermostat itself or remotely via the **Total Connect Comfort app**, providing flexibility in temperature adjustments.

6. **Geofencing Capability** When paired with TCC, it can **automatically adjust settings** based on your location (e.g., turning off AC when you leave home).

7. **Durability and Reliability** Honeywell is a well-established brand known for **long-lasting thermostats**, and this model has a solid reputation for stability in residential use.

8. **Compatibility with Smart Plugs and Sensors** Can integrate with **Honeywell smart sensors** (e.g., room sensors for better temperature control) and work with **smart plugs** for enhanced automation.

9. **Low-Energy Mode** Helps reduce standby power consumption when not in use.

10. **Warranty and Customer Support** Comes with a **limited warranty** (typically 1 year on parts and labor) and Honeywell s customer support is generally reliable for troubleshooting.

---

1. **Higher Upfront Cost** Compared to basic programmable or smart thermostats (e.g., Nest, Ecobee), this model is **more expensive**, which may not be justified for users with simple HVAC needs.

2. **Dependence on Total Connect Comfort (TCC) Subscription** While the basic features work without a subscription, **full remote access, advanced automation, and geofencing require a paid TCC plan** ( $4.99/month or $49.99/year). Some users may find this recurring cost unnecessary.

3. **Learning Curve for Advanced Features** While the interface is user-friendly, **setting up complex schedules, automations, or integrating with third-party smart home systems** may require some initial effort.

4. **Limited Local Wi-Fi Support (Requires TCC Bridge)** Unlike some competitors (e.g., Nest, Ecobee), this thermostat **does not have built-in Wi-Fi**; it relies on the **Total Connect Comfort bridge** (sold separately) for smart functionality. This adds extra hardware cost and setup complexity.

5. **No Built-in Display for Non-Smart Users** If you **don t use the app or TCC**, the thermostat functions as a basic digital display, which may feel underwhelming compared to standalone smart thermostats.

6. **Potential Compatibility Issues with Older HVAC Systems** While it supports many systems, **very outdated or non-standard HVAC setups** may require additional wiring or compatibility checks, which could void warranties or require professional installation.

7. **No Built-in Air Quality Monitoring** Unlike some newer smart thermostats (e.g., Ecobee), it **does not measure humidity, CO2, or air quality**, limiting its smart home capabilities in that regard.

8. **App Performance Variability** Some users report **lag or occasional connectivity issues** with the Total Connect Comfort app, which can be frustrating for remote control.

9. **No Voice Control Without Additional Setup** While it works with Alexa and Google Assistant, **full voice control may require extra configuration**, unlike plug-and-play setups with other smart thermostats.

10. **Battery Dependency (for Remote Sensors)** If you use **wireless sensors** (e.g., room sensors), they require **regular battery replacements**, adding minor maintenance overhead.

---

### **Conclusion**

The **Honeywell 900C51-0021** is a **solid mid-to-high-end smart thermostat** that excels in **integration with Honeywell s ecosystem, energy efficiency, and remote control**. It is particularly well-suited for:

- **Homeowners already using Honeywell HVAC systems or Total Connect Comfort**.

- **Users who prioritize compatibility with Alexa, Google Assistant, and HomeKit**.

- **Those who want advanced scheduling, geofencing, and automation without needing a third-party thermostat**.

- **Budget-conscious buyers** (due to higher cost and potential subscription fees).

- **Users who prefer standalone smart thermostats** (e.g., Nest, Ecobee) with built-in Wi-Fi and no reliance on a separate bridge.

- **Those with very basic HVAC needs** who don t require smart features.

---

### **Recommendation**

You **already have Honeywell HVAC equipment** and want seamless integration.

You **use or plan to use Total Connect Comfort** for remote monitoring and control.

You **value advanced scheduling, geofencing, and multi-zone support**.

You **prefer a brand with strong reliability and customer support**.

You want a **standalone smart thermostat with built-in Wi-Fi** (e.g., **Nest Learning Thermostat, Ecobee SmartThermostat**).

You **don t mind a subscription fee** and prefer a **lower upfront cost** (e.g., **Google Nest, Ecobee**).

You **need air quality monitoring or humidity control** (e.g., **Ecobee s built-in sensors**).

You **have a simple HVAC system** and don t need advanced smart features.

The **Honeywell 900C51-0021 is a strong choice for users deeply invested in the Honeywell smart home platform**, but it may not offer the best value for those seeking a **plug-and-play, subscription-free smart thermostat**. If you re committed to the ecosystem, it s a **reliable, feature-rich option** otherwise, competitors like **Ecobee or Nest** might be more flexible and cost-effective.

Details:

All products are guaranteed to be working but may show signs of use if purchasing a used product. HONEYWELL 900C51-0021 / 900C510021 USED DISCONTINUED BY MANUFACTURER, CPU ASSEMBLY, 600 MA MAX, 5VDC. Call to use a shipping service other than the ones listed. Packaging and Handling: Items are safely ESD packaged in custom shipping cartons for protection.

Sells new and surplus product develops channels to purchase such.

part #: 900c510021 prices

• $350.00-$921.83

specifications sensoindustria:

• brand: Honeywell
• mpn: 900c51-0021
• part type: Module

offer sensoindustria:

• quantity: 1
• started: March 5, 2026
• options: Ship-to-home
• best offers: True
• availability: In Stock
• sold: 0

shipping sensoindustria:

• class: Standard
• service: Standard
• transit: 29-34 Days
• cost: $12.90
• type: Fixed

seller sensoindustria:

• # reviews: 193014
• city: 1 Millennium Dr, Willingboro, NJ 08046
• rating: 99.6%

payments sensoindustria:

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

returns sensoindustria:

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

general sensoindustria:

• condition: Used
• PLCs HMIs > PLC Peripheral Modules > PLC Input Output Modules

Honeywell 900C51-0021 Is Similar To:

• 30731811-001 Honeywell Used Output Card (35.9% similar) E-mail any questions. Part is very clean and comes in an open static bag. 1 used Honeywell output card. Shipping costs are based on rate, packaging material, gas, and labor...(April 9th, 2018)
• 51304453-100 Honeywell Used Analog Input Sti Termination Board Rev (26.7% similar) This is a used Honeywell analog input high level sit termination board. If an item is over 5,000. Pre-purchase inspection: if you would like to arrange for a technician come in and test unit or inspect before purchase, please any time make arrangements. Please with any questions. Model: MU-TAIH02 ...(May 8th, 2018)
• 51304481-100 Honeywell Used Ucn Low Level Analog Input Card Hdw Fw (26.7% similar) If an item is over 5,000. Pre-purchase inspection: if you would like to arrange for a technician come in and test unit or inspect before purchase, please any time make arrangements. This is a used Honeywell low level analog input card. If you would like to schedule an appointment inspect item, or ...(May 4th, 2018)
• 51304487-150 Honeywell Used Ucn Digital Output Card Hdw Fw (28.9% similar) Please with any questions. Save thousands and buy used from green industrial today. All products are advertised outside of. This is a used Honeywell digital output card. Include delivery confirmation. Pre-purchase inspection: if you would like to arrange for a technician come in and test unit or ...(May 7th, 2018)
• 51309152-175 Honeywell Used Ucn Analog Output Card Hwd Fw (29.2% similar) Pre-purchase inspection: if you would like to arrange for a technician come in and test unit or inspect before purchase, please any time make arrangements. If you would like to schedule an appointment inspect item, or pick it up, please directly. Save thousands and buy used from green industrial ...(March 6th, 2019)
• 621-1180r Honeywell Used Series Input Module (33.7% similar) Please with any questions. Include delivery confirmation. Save thousands and buy used from green industrial today. All products are advertised outside of. This is a used Honeywell input module. If you would like to schedule an appointment inspect item, or pick it up, please directly. Series: 620 ...(March 26th, 2018)
• 900a01-0102 Honeywell Ai Channel Controller Used Analog Input (34% similar) 8 channel analog input module used for Honeywell HC900 controllers n 900A01-0102 AI this is used, in excellent condition, and fully functional...(May 11th, 2018)
• 900b01-0101 Honeywell Ao Channel Controller Used Analog Output (33.7% similar) All are in fully functional, excellent condition see my other offers for more HC900 modules thanks looking and happy buying...(May 11th, 2018)
• 900c53-0142-00 Honeywell Scanner Controller Used (39.1% similar) I o scanner module used for Honeywell HC900 controllers n 900C53 this is used, in excellent condition, and fully functional...(August 1st, 2018)
• 900g01-0102 Honeywell Di Channel Controller Used Digital Input (33.7% similar) 16 channel digital input module used for Honeywell HC900 controllers n 900G01-0102 DI this is used, in excellent condition, and fully functional. All are in fully functional, excellent condition...(May 11th, 2018)
• 900h01-0102 Honeywell Digital Out Relay Channel Controller Used (33.3% similar) All are in fully functional, excellent condition see my other offers for more HC900 modules thanks looking and happy buying. 8 channel digital out relay module used for Honeywell HC900 controllers n 900H01-0102 this is used, in excellent condition, and fully functional...(May 11th, 2018)