Field Control CAS-34U Fan-In-A-Can 120V Makeup Air Unit

Original price was: $467.89.Current price is: $437.65.

9 in stock

SKU: 1732457 Category:


The Field Control CAS-34U Fan-In-A-Can 120V Makeup Air Unit is a versatile device used in combustion appliance systems to ensure proper ventilation and safety. Here’s a breakdown of its key features and functions:


  • Provides combustion air for appliances: Delivers fresh air from outside to burners in furnaces, boilers, water heaters, and other combustion appliances.
  • Prevents negative pressure: Combats the pressure imbalance caused by exhaust fans, ensuring proper venting and preventing backdrafting of flue gases.
  • Improves appliance efficiency: Optimizes combustion with fresh air supply, leading to more efficient fuel burning and potentially lower energy costs.
  • Enhances safety: Reduces the risk of carbon monoxide poisoning by preventing flue gases from entering the living space.

Key Features:

  • Dual voltage compatibility: Operates on both 120VAC and 24VAC control systems, offering installation flexibility.
  • Compact design: Fits easily in confined spaces near the appliance.
  • Fan and pressure switch combination: Integrates both functions into one unit, simplifying installation and maintenance.
  • Variable air volume control: Allows for adjusting airflow to match specific appliance requirements.
  • Proven safety features: Includes a proving switch that ensures the appliance burner doesn’t operate until sufficient airflow is established.
  • Durable construction: Features corrosion-resistant materials for long-lasting performance.
  • Easy installation: Typically installed on an exterior wall near the appliance and connected to the combustion air intake.


  • Residential and commercial heating systems (furnaces, boilers)
  • Water heaters
  • Other gas-fired appliances like fireplaces and ranges

Things to Consider:

  • Appliance compatibility: Verify the CAS-34U’s air output and pressure meet the specific requirements of your appliance.
  • Local building codes: Consult local regulations regarding makeup air unit requirements for combustion appliances.
  • Professional installation recommended: While DIY installation is possible for experienced individuals, consulting a qualified HVAC technician is recommended for optimal performance and safety when dealing with gas lines and ventilation systems.

Overall, the Field Control CAS-34U Fan-In-A-Can 120V Makeup Air Unit is a reliable and versatile solution for providing combustion air and ensuring proper ventilation in various gas-fired appliance systems. Its dual voltage compatibility, compact design, safety features, and ease of installation make it a popular choice for both homeowners and professionals.


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