Why Your Under-Sized HVAC System Cools but Doesn’t Comfort

Cold Air, But Still Uncomfortable? Here’s Why

You’ve set your AC to a comfortable 22°C. The room feels cold, but something’s off. The air is stuffy, sticky, or overly dry. That’s because your HVAC system might be undersized or improperly designed, cooling the air without effectively managing humidity levels.

What Really Happens with an Undersized HVAC System

1. The System Runs Continuously

An under-capacity HVAC system struggles to meet the desired temperature. So, it runs longer, consuming more energy and causing uneven airflow.

2. Overcooling and Dry Air

As it runs non-stop, the system begins to strip too much moisture from the air, leading to dry eyes, sore throat, and an uncomfortable indoor environment.

3. Humidity Surges Back After Shutdown

Once the system finally stops, moisture from the outside or internal sources rushes back, creating a clammy, damp atmosphere. This results in frequent humidity swings that strain electronics, damage furnishings, and increase mold risk.

Why Humidity Control is as Important as Cooling

Proper HVAC Design = Comfort + Air Quality

✔️ A right-sized HVAC unit cools the room efficiently and cycles off naturally.
✔️ It removes excess moisture while maintaining indoor humidity at optimal levels (40–60%).

Poorly Sized HVAC = Unstable Indoor Conditions

❌ It runs constantly without adequate dehumidification.
❌ Air becomes either too dry or too humid, affecting comfort, health, and equipment longevity.

Result:

• Respiratory discomfort
  
• Higher risk of mold and mildew
  
• Increased energy bills due to inefficient cycling
  

How to Fix HVAC Sizing and Humidity Issues

1. Get a Professional Load Calculation

Start with a Manual J load calculation. This measures the exact heating and cooling load your space needs, based on orientation, insulation, windows, and occupancy, not just square footage.

How do I know if my HVAC system is the wrong size?

A system that runs constantly, cools unevenly, or leads to dry or damp indoor air is often a sign of improper sizing.

2. Consider Adding a Dehumidifier

In humid environments, even a well-sized HVAC may struggle during peak seasons. A dedicated dehumidifier can ease the load on your system and keep humidity in check.

3. Adjust Thermostat and Fan Settings

• Use “Dry Mode” if your system supports it—it focuses on removing moisture.
  
• Set fan to “Auto” instead of “On” to ensure condensate drains properly, preventing moisture recirculation.
  

Final Thought: Comfort Is About Balance

A properly designed HVAC system should cool efficiently without compromising air quality. If your space feels cold but uncomfortable, the issue likely lies in HVAC sizing or humidity management.

Get a professional to inspect your setup. Fixing this now prevents higher energy bills, health issues, and unnecessary wear on your equipment.