Bypass Factor and Coil Effectiveness: ADP, Contact Factor, and Dehumidification

1. Introduction

This guide provides a comprehensive deep dive into the critical psychrometric concepts of Bypass Factor, Coil Effectiveness, Apparatus Dew Point (ADP), Contact Factor, and their role in HVAC dehumidification. It is intended for HVAC engineers, technicians, designers, and students seeking to deepen their understanding of coil performance and optimize HVAC system design for effective humidity control.

2. Technical Background

Bypass Factor (BPF)

The Bypass Factor (BPF) represents the fraction of air that passes through a cooling or heating coil without coming into contact with the coil surface. This portion of air remains unaltered in its state. A lower bypass factor indicates better coil performance and more effective heat and moisture transfer.

Equation:

BPF = (xB - xC) / (xA - xC) = (hB - hC) / (hA - hC) = (TB - TC) / (TA - TC) [1]

Where: * BPF = Bypass Factor * xA, xB, xC = Humidity ratios at conditions A (inlet air), B (outlet air), and C (coil surface/ADP) respectively. * hA, hB, hC = Enthalpies of humid air at conditions A, B, and C respectively (J/kg_dry_air or kJ/kg_dry_air). * TA, TB, TC = Temperatures of humid air at conditions A, B, and C respectively (K or °C).

Contact Factor (CF) / Coil Effectiveness

The Contact Factor (CF), also known as Coil Effectiveness, is the complement of the Bypass Factor. It represents the fraction of air that does come into contact with the coil surface and undergoes heat and moisture transfer. A higher contact factor signifies a more effective coil.

Equation:

CF = 1 - BPF = (xA - xB) / (xA - xC) = (hA - hB) / (hA - hC) = (TA - TB) / (TA - TC) [1]

Where: * CF = Contact Factor / Coil Effectiveness * BPF = Bypass Factor * xA, xB, xC = Humidity ratios at conditions A (inlet air), B (outlet air), and C (coil surface/ADP) respectively. * hA, hB, hC = Enthalpies of humid air at conditions A, B, and C respectively (J/kg_dry_air or kJ/kg_dry_air). * TA, TB, TC = Temperatures of humid air at condition A, B, and C respectively (K or °C).

Apparatus Dew Point (ADP)

The Apparatus Dew Point (ADP) is the effective surface temperature of a cooling coil when dehumidification occurs. It is the theoretical temperature to which all the supply air would be cooled if 100% of the air contacted the coil surface and reached saturation. On a psychrometric chart, the ADP is the intersection point of the Grand Sensible Heat Factor (GSHF) line with the saturation curve [2].

Significance: The ADP is a crucial parameter for designing and analyzing cooling and dehumidification processes. It represents the lowest achievable temperature and highest dehumidification potential for a given coil and operating conditions.

Dehumidification

Dehumidification in HVAC systems primarily occurs when moist air passes over a cooling coil whose surface temperature is below the dew point of the entering air. As the air cools, its relative humidity increases, and when it reaches saturation, water vapor condenses on the coil surface, removing moisture from the air stream.

Cooling Requirements (Heat Flow Rate):

Qcooling = m_air * (hA - hB) = m_air * Cp_air * (TA - TB) + m_air * h_vap * (xA - xB) [1]

Where: * Qcooling = Heat flow rate or power required to cool air from condition A to B (kW). * m_air = Mass flow rate of air (kg/s). * hA, hB = Enthalpies of humid air at condition A (inlet) and B (outlet) respectively (kJ/kg_dry_air). * Cp_air = Specific heat capacity of air (approx. 1.01 kJ/kg.°C). * h_vap = Enthalpy of vaporization of water (approx. 2502 kJ/kg). * TA, TB = Temperatures of humid air at condition A and B respectively (°C). * xA, xB = Humidity ratios at condition A and B respectively.

3. Step-by-Step Procedures or Design Guide

Determining Coil Performance using a Psychrometric Chart

1. Plot Inlet Air Condition (Point A): Locate the dry-bulb temperature and wet-bulb temperature (or relative humidity) of the air entering the coil on the psychrometric chart.
2. Plot Outlet Air Condition (Point B): Locate the desired or measured dry-bulb temperature and wet-bulb temperature (or relative humidity) of the air leaving the coil.
3. Determine Apparatus Dew Point (Point C): Draw a straight line connecting Point A and Point B. Extend this line until it intersects the saturation curve. This intersection point is the ADP (Point C). The temperature at this point is the ADP temperature.
4. Calculate Contact Factor (CF): Using the humidity ratios (x) or enthalpies (h) from points A, B, and C, calculate the Contact Factor: CF = (xA - xB) / (xA - xC) or CF = (hA - hB) / (hA - hC).
5. Calculate Bypass Factor (BPF): BPF = 1 - CF.

4. Selection and Sizing

Effective selection and sizing of HVAC coils are crucial for achieving desired indoor conditions, particularly for dehumidification. Psychrometric analysis is fundamental in this process, allowing engineers to translate heating or cooling loads into specific airflow rates and determine the appropriate coil characteristics [3].

Key Considerations for Coil Sizing:

• Cooling Load Estimation: The total cooling load, comprising sensible and latent heat gains, must be accurately determined. This involves analyzing building characteristics, occupancy, internal heat gains, and outdoor air loads [3].
• Design Supply Airflow Rate: Psychrometrics are used to calculate the required volume flow rate of air (CFM) to meet the estimated loads. This directly impacts the sizing of fans, ducts, and air-handling units [3].
  • Room Sensible Heat (RSH) Calculation: CFM = RSH / [1.08 x (T_Room – T_Supply Air)] [3] Where:
    • CFM = Cubic Feet per Minute (airflow rate)
    • RSH = Room Sensible Heat (Btu/hr)
    • T_Room = Room dry-bulb temperature (°F)
    • T_Supply Air = Supply air dry-bulb temperature (°F)
  • Grand Sensible Heat (GSH) Calculation (for apparatus): CFM = GSH / [1.08 x (T_Mixed Air – T_Coil Leaving)] [3] Where:
    • GSH = Grand Sensible Heat (Btu/hr)
    • T_Mixed Air = Mixed air dry-bulb temperature entering the coil (°F)
    • T_Coil Leaving = Coil leaving dry-bulb temperature (°F)
• Apparatus Dew Point (ADP): For dehumidification, the cooling coil’s surface temperature must be below the dew point of the entering air. The ADP is a critical design parameter, representing the effective coil surface temperature required to achieve the desired leaving air conditions [2, 3].
• Latent Cooling Capacity: Coils must be selected with sufficient latent cooling capacity to remove the required amount of moisture from the air. This is particularly important in humid climates or applications with high internal latent loads [3].
• Coil Configuration (Draw-through vs. Blow-through): The arrangement of the fan relative to the coil impacts performance. Draw-through units typically require more supply air due to fan heat addition after the coil, while blow-through units add fan heat before the coil, potentially leading to higher saturation of leaving air [3].
• Coil Load Calculation: The total cooling coil load (Q_coil) can be calculated using the mass flow rate of air and the enthalpy difference across the coil: Q_coil = m_air * (h_mixed air - h_coil leaving) or Q_coil = 4.5 x CFM x (h_mixed air - h_coil leaving) [3] Where:
  • m_air = Mass flow rate of air (lb/hr)
  • h_mixed air = Enthalpy of mixed air entering the coil (Btu/lb_dry_air)
  • h_coil leaving = Enthalpy of air leaving the coil (Btu/lb_dry_air)

Using the Psychrometric Chart for Sizing:

The psychrometric chart is an indispensable tool for coil selection. By plotting the entering and leaving air conditions, and extending the process line to the saturation curve to find the ADP, engineers can visualize the coil’s performance and ensure it meets both sensible and latent load requirements [3].

5. Best Practices

Optimizing bypass factor, coil effectiveness, and ADP is essential for efficient HVAC system operation and effective dehumidification. Adhering to industry best practices and standards ensures reliable performance, energy efficiency, and occupant comfort.

Coil Maintenance and Cleaning:

• Regular Filter Replacement: Regularly changing air filters prevents dust and debris accumulation on coils, which can significantly impede heat transfer and increase bypass factor [4].
• Scheduled Coil Cleaning: Cooling coils should be cleaned at least once a year, or more frequently depending on the operating environment, to maintain efficiency and prevent costly repairs. Dirty coils force the system to work harder, leading to higher energy consumption [5, 6].
• Ensure Unrestricted Airflow: Poor airflow due to blockages or improper duct design can accelerate coil fouling and reduce effectiveness [7].

Coil Design and Selection:

• Enhanced Coil Design: Utilizing coils with optimized designs maximizes heat exchange and reduces energy consumption. Factors like fin spacing, tube diameter, and coil depth influence contact factor and overall efficiency [8].
• Proper Sizing: As discussed in Section 4, accurate sizing based on psychrometric analysis ensures the coil can meet both sensible and latent load requirements effectively.
• Material Selection: Corrosion-resistant materials and coatings can extend coil lifespan and maintain performance over time.

Operational Best Practices:

• Maintain Optimal Refrigerant Charge: Incorrect refrigerant levels can severely impact coil performance and dehumidification capabilities.
• Control Airflow Velocity: Maintaining appropriate airflow velocity across the coil is crucial. Too high a velocity can increase bypass factor, while too low can reduce overall capacity.
• Utilize Advanced Controls: Implementing advanced control strategies, such as those outlined in ASHRAE guidelines, can optimize coil operation for varying load conditions and improve dehumidification control [9].

ASHRAE Standards and Guidelines:

ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) provides numerous standards and guidelines relevant to HVAC system design and operation, including psychrometrics and coil performance. While specific standards directly detailing bypass factor optimization are integrated into broader design principles, adherence to standards like ASHRAE 90.1 (Energy Standard for Buildings Except Low-Rise Residential Buildings) and ASHRAE Guideline 36 (High-Performance Sequences of Operation for HVAC Systems) indirectly promotes efficient coil operation and effective dehumidification [10, 11]. These standards emphasize energy efficiency, proper system design, and control strategies that contribute to optimal psychrometric performance.

6. Troubleshooting

Effective troubleshooting of HVAC coil performance and dehumidification issues requires a systematic approach, often leveraging psychrometric principles to diagnose problems accurately. Common issues can stem from design flaws, improper installation, or inadequate maintenance.

Common Problems and Solutions:

• Insufficient Cooling or Dehumidification:
  • Problem: The system is running, but the space remains warm and/or humid.
  • Diagnosis: This could be due to an oversized unit (short cycling), low refrigerant charge, dirty coils, or restricted airflow. Psychrometric analysis might reveal that the coil is not reaching the required ADP or that the bypass factor is too high [20].
  • Solution: Verify refrigerant charge, clean coils and filters, check for proper airflow, and ensure the system is correctly sized for the load. For oversized units, consider strategies like hot gas bypass or reheat to improve dehumidification without overcooling.
• Coil Freezing:
  • Problem: Ice formation on the evaporator coil.
  • Diagnosis: Often caused by low airflow (dirty filter, blocked coil, fan malfunction), low refrigerant charge, or a faulty expansion valve.
  • Solution: Check and replace air filters, clean coils, inspect fan operation, and verify refrigerant levels.
• Excessive Energy Consumption:
  • Problem: High electricity bills without a corresponding improvement in comfort.
  • Diagnosis: Dirty coils, incorrect airflow, oversized equipment, or poor insulation can all contribute to inefficiency. A high bypass factor means the system is working harder to achieve desired conditions [4, 5, 6].
  • Solution: Implement regular maintenance, optimize airflow, and ensure proper system sizing and insulation.
• Poor Indoor Air Quality (IAQ):
  • Problem: Musty odors, mold growth, or occupant complaints about stuffiness.
  • Diagnosis: Inadequate dehumidification leading to high indoor humidity. This can be exacerbated by an oversized system that doesn’t run long enough to remove latent heat [13].
  • Solution: Improve dehumidification strategies, ensure proper ventilation, and address any sources of moisture intrusion.

7. Safety and Compliance

Adherence to safety protocols and compliance with relevant codes and regulations are paramount in HVAC system design, installation, and maintenance, especially concerning psychrometric performance and dehumidification. These measures ensure not only operational efficiency but also occupant health and safety.

Indoor Air Quality (IAQ) and Health:

• Moisture Control: Effective dehumidification is critical for maintaining healthy indoor air quality. High humidity levels can lead to mold growth, dust mite proliferation, and bacterial growth, contributing to respiratory issues and allergies. HVAC systems must be designed to control humidity within acceptable ranges, typically below 60% relative humidity [13].
• ASHRAE Standard 62.1: This standard, "Ventilation for Acceptable Indoor Air Quality," provides minimum ventilation rates and other measures intended to provide IAQ that is acceptable to human occupants and minimizes adverse health effects. Proper psychrometric design, including effective dehumidification, is essential to meet these IAQ requirements [13].

Energy Efficiency and Environmental Regulations:

• ASHRAE Standard 90.1: "Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings" sets minimum energy efficiency requirements for the design and construction of new buildings and their systems, including HVAC. Efficient coil performance, optimized bypass factors, and precise ADP control contribute directly to meeting these energy efficiency goals [10].
• Refrigerant Management: Compliance with environmental regulations regarding refrigerant handling, leak detection, and disposal (e.g., EPA regulations in the United States) is crucial. Improper refrigerant management can lead to environmental damage and system inefficiency.

System Maintenance and Operational Safety:

• Regular Maintenance: Consistent maintenance, including coil cleaning and filter replacement, is not only an operational best practice but also a safety measure. Dirty coils can lead to reduced airflow, increased energy consumption, and potential system malfunctions, including frozen coils, which can pose safety risks [4, 5, 6].
• Electrical Safety: All electrical components of HVAC systems must be installed and maintained according to local electrical codes (e.g., National Electrical Code - NEC). Proper wiring, grounding, and overcurrent protection are essential to prevent electrical hazards.
• Drainage and Condensate Management: Proper design and maintenance of condensate drainage systems are vital to prevent water leaks, which can cause structural damage, promote mold growth, and create slip hazards. Drain pans should be kept clean to prevent microbial growth [14].

8. Cost and ROI

Investing in proper psychrometric analysis, optimizing coil effectiveness, managing bypass factor, and ensuring effective dehumidification yields significant financial benefits and a strong return on investment (ROI) for HVAC systems. These benefits extend beyond immediate energy savings to include prolonged equipment life, reduced maintenance costs, and improved occupant productivity.

Energy Efficiency and Cost Savings:

• Reduced Energy Consumption: High-performance HVAC systems, achieved through optimized coil design and psychrometric control, can reduce energy costs by 30-40% [15]. By minimizing the bypass factor and maximizing coil effectiveness, less energy is wasted on conditioning air that doesn't fully interact with the coil.
• Optimized Dehumidification: Effective dehumidification reduces the latent load on the cooling coil, allowing the system to operate more efficiently. In many cases, dedicated dehumidification strategies or optimized cooling coils can lead to substantial energy savings by reducing overall HVAC runtime [16, 17].
• Lower Operating Costs: Precise control over temperature and humidity reduces the strain on HVAC components, leading to lower electricity bills and operational expenses.

Extended Equipment Lifespan and Reduced Maintenance:

• Preventative Maintenance: Regular coil cleaning and maintenance, driven by an understanding of psychrometric performance, prevents premature equipment failure and extends the lifespan of HVAC systems [4, 5, 6]. This reduces the frequency and cost of major repairs or replacements.
• Reduced Wear and Tear: Efficiently operating coils and systems experience less stress, leading to fewer breakdowns and lower maintenance requirements. This translates to significant savings over the life of the equipment.

Improved Indoor Air Quality and Productivity:

• Health and Comfort: Maintaining optimal humidity levels through effective dehumidification prevents mold growth and improves indoor air quality, leading to a healthier and more comfortable environment for occupants [13].
• Increased Productivity: Comfortable and healthy indoor environments contribute to increased productivity and reduced absenteeism in commercial and institutional settings. While difficult to quantify directly, the impact on human performance represents a substantial indirect ROI.

Quick Return on Investment:

Many improvements related to coil effectiveness and dehumidification, such as enhanced coil coatings or optimized control strategies, can offer a quick ROI, sometimes within 12 months, through significant energy savings and reduced operational costs [18]. The initial investment in psychrometric analysis and system optimization is often recouped rapidly through these tangible benefits.

9. Common Mistakes

Even experienced HVAC professionals can make mistakes when dealing with psychrometrics, coil effectiveness, bypass factor, ADP, and dehumidification. Avoiding these common pitfalls is crucial for optimal system performance, energy efficiency, and occupant comfort.

• Ignoring Bypass Factor: A common error is to assume 100% contact between air and the coil, effectively ignoring the bypass factor. This leads to underestimating the actual leaving air temperature and humidity, resulting in undersized coils or inadequate dehumidification [19].
• Improper Coil Sizing (Oversizing or Undersizing):
  • Oversizing: An oversized cooling coil can lead to short cycling, where the system turns on and off too frequently. This reduces run time, preventing adequate dehumidification and leading to high indoor humidity despite comfortable temperatures [20].
  • Undersizing: An undersized coil will struggle to meet the sensible and latent loads, resulting in insufficient cooling and dehumidification.
• Incorrect Airflow Velocity: Operating the system with airflow velocities that are too high across the coil can significantly increase the bypass factor, reducing coil effectiveness and dehumidification capacity [12]. Conversely, excessively low airflow can lead to freezing coils.
• Neglecting Coil Maintenance: Failing to regularly clean coils and replace air filters is a frequent mistake. Dirty coils drastically reduce heat transfer efficiency, increase pressure drop, and lead to higher energy consumption and reduced dehumidification [4, 5, 6].
• Misinterpreting Psychrometric Chart Data: Errors can occur when plotting points or reading values from the psychrometric chart, especially when dealing with complex processes or interpolating between lines. This can lead to incorrect calculations for coil performance and system design [21].
• Confusing Dew Point and Dry Bulb Temperature: While related, these are distinct properties. Misunderstanding their relationship, particularly in the context of ADP, can lead to design flaws where the coil surface temperature is not low enough to achieve the desired dehumidification.
• Inadequate Condensate Management: Poorly designed or maintained condensate drainage systems can lead to water accumulation, which can cause mold growth, water damage, and reduce system efficiency [14].
• Ignoring Latent Load in Design: Focusing solely on sensible cooling and neglecting the latent heat load can result in systems that cool effectively but fail to control humidity, leading to uncomfortable and unhealthy indoor environments.
• Improper Thermostat Settings: Using thermostat settings like "fan only" mode can circulate humid air without passing it over the cooling coil, disrupting dehumidification and increasing indoor humidity [22].

10. FAQ Section

Q1: What is the primary difference between Bypass Factor and Contact Factor?

A1: The Bypass Factor (BPF) represents the fraction of air that passes through a cooling or heating coil without coming into contact with the coil surface, thus remaining unconditioned. Conversely, the Contact Factor (CF), also known as Coil Effectiveness, is the fraction of air that does make contact with the coil surface and undergoes heat and moisture transfer. Essentially, CF = 1 - BPF. A lower BPF and higher CF indicate a more efficient coil performance [1].

Q2: How does Apparatus Dew Point (ADP) influence dehumidification in an HVAC system?

A2: The Apparatus Dew Point (ADP) is the effective surface temperature of a cooling coil when dehumidification occurs. It is the theoretical temperature to which all the supply air would be cooled if 100% of the air contacted the coil surface and reached saturation. On a psychrometric chart, the ADP is the intersection point of the Grand Sensible Heat Factor (GSHF) line with the saturation curve [2].

Q3: Why is proper coil sizing crucial for effective dehumidification, and what are the risks of oversizing or undersizing?

A3: Proper coil sizing is crucial because it directly impacts the system’s ability to meet both sensible (temperature) and latent (humidity) loads. An oversized coil can lead to short cycling, where the system turns off before it can adequately remove moisture, resulting in high indoor humidity despite comfortable temperatures [20]. An undersized coil, on the other hand, will struggle to meet the required cooling and dehumidification loads, leading to uncomfortable conditions and increased energy consumption. Accurate psychrometric analysis is essential for correct sizing [3].

Q4: What are some common operational mistakes that can negatively impact coil effectiveness and dehumidification?

A4: Several operational mistakes can reduce coil effectiveness and hinder dehumidification. These include neglecting regular coil cleaning and filter replacement, which leads to dirty coils and increased bypass factor [4, 5, 6]. Operating with incorrect airflow velocity can also be detrimental; too high a velocity increases bypass, while too low can cause coil freezing. Additionally, improper thermostat settings, such as using "fan only" mode, can circulate humid air without conditioning, undermining dehumidification efforts [12, 22].

Q5: How do ASHRAE standards contribute to optimizing bypass factor and dehumidification in HVAC systems?

A5: ASHRAE standards provide essential guidelines for HVAC system design and operation, indirectly contributing to optimized bypass factor and dehumidification. For instance, ASHRAE Standard 62.1 sets minimum ventilation rates and indoor air quality requirements, which necessitate effective humidity control [13]. ASHRAE Standard 90.1 focuses on energy efficiency, promoting designs that minimize energy waste, including those that optimize coil performance and reduce bypass factor [10]. Adherence to these standards ensures systems are designed for both energy efficiency and healthy indoor environments.

References

[1] myengineeringtools.com. “Contact factor and Bypass factor of air cooling coils.” https://myengineeringtools.com/Air/AHU_Bypass_Factor.html
[2] hvactechguide.com. “Apparatus Dew point (ADP).” https://hvactechguide.com/apparatus-dew-point-adp/
[3] CED Engineering. “Air Conditioning Psychrometrics.” https://www.cedengineering.com/userfiles/M05-005%20-%20Air%20Conditioning%20Psychrometrics%20-%20US.pdf
[4] AC Direct. “HVAC Coil Cleaning: How To Improve Efficiency.” https://www.acdirect.com/blog/hvac-coil
[5] NADCA. “All About Coil Cleaning.” https://nadca.com/blog/all-about-coil-cleaning
[6] Total Comfort Cooling. “How Often Clean AC Coils: Expert Tips for Optimal Performance.” https://totalcomfortcooling.com/how-often-clean-ac-coils-expert-tips-for-optimal-performance/
[7] Illumipure. “Best Practices for Coil Maintenance and Bioremediation.” https://illumipure.com/best-practices/coil-maintenance-and-bioremediation/
[8] Rahn Industries. “Custom Coil Solutions: How to Improve HVAC Efficiency.” https://rahnindustries.com/2025/03/31/custom-coil-solutions-how-to-improve-hvac-efficiency/
[9] ASHRAE. “High Performance Sequences of Operation for HVAC.” https://www.ashrae.org/file%20library/technical%20resources/standards%20and%20guidelines/standards%20addenda/g36_2018_y_20210709.pdf
[10] EnergyCodes.gov. “ANSI/ASHRAE/IES Standard 90.1-2019 Performance.” https://www.energycodes.gov/sites/default/files/2023-12/90_1_2019_Appendix_G_PRM_2023.11.pdf
[11] LinkedIn. “How to Optimize Cooling Coils with Bypass Factor.” https://www.linkedin.com/posts/shahbaz-ashraf-235278198_hvac-coolingcoils-bypassfactor-activity-7377823887570608131-DjUl
[12] LinkedIn. “Understanding Coil By-Pass Factor in HVAC.” https://www.linkedin.com/pulse/understanding-coil-by-pass-factor-hvac-jules-williams-be6nc
[13] ASHRAE. “Ventilation for Acceptable Indoor Air Quality.” https://www.ashrae.org/file%20library/technical%20resources/standards%20and%20guidelines/standards%20addenda/62.1-2016/62_1_2016_ae_20190826.pdf
[14] Ketchum & Walton. “HVAC Coil Protection 101.” https://ketchumandwalton.com/hvac-coil-protection-101/
[15] Project HVAC. “HVAC System ROI: Maximizing Value for Your Property.” https://projecthvac.com/2025/08/17/hvac-system-roi-maximizing-value-for-your-property/
[16] Phil's Heating and Air. “How a Dehumidifier Can Extend the Life of Your HVAC System.” https://www.philsheatingandair.com/how-a-dehumidifier-can-extend-the-life-of-your-hvac-system
[17] Innovative Dehumidifiers. “Humidity Hack: Save Energy at Home With a Dehumidifier.” https://www.innovativedehumidifiers.com/humidity-hack-save-energy-at-home-with-a-dehumidifier/
[18] BP Coils. “Innovative HVAC Coil Coatings: A Key to Energy Efficiency, ...” https://bpcoils.com/hvac/hvac-coil-coatings/
[19] LinkedIn. “How to avoid mistakes in psychrometric analysis.” https://www.linkedin.com/posts/ir-yokelee-tan-pepc-mi-fire-441724111_when-doing-psychrometric-analysis-the-shf-activity-7322823971903520772-8qnx
[20] Lennox. “Why Your AC is Cooling but Not Removing Humidity.” https://www.lennox.com/residential/lennox-life/consumer/ac-is-cooling-but-not-removing-humidity
[21] Dương HVAC. “Understanding the Psychrometric Chart.” https://duonghvavc.wordpress.com/2025/11/10/understanding-the-psychrometric-chart-the-backbone-of-hvac-design/
[22] Proprice AC. “Understanding Dehumidification in a Modern HVAC System.” https://www.propriceac.com/blog/2024/october/understanding-dehumidification-in-a-modern-hvac-/

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