⚠️ Clogged HEPA Filters: 5 Hidden Risks That Damage Your Cleanroom & Drain Your Energy

How clogged HEPA filters affect HVAC AHU performance- Major cleanroom HVAC issues

✅ Enhanced Air Purity

HEPA filters remove 99.97% of particles ≥0.3 microns, including dust, bacteria, and allergens. When installed in an AHU, this ensures that the air distributed across rooms or clean zones is ultra-clean and safe.

✅ Protection of Downstream Equipment

By capturing fine particles early, HEPA filters protect:

• Cooling and heating coils

•  Ductwork

•  Terminal diffusers

This reduces wear and tear and lowers maintenance costs.

✅Improved Indoor Air Quality (IAQ)

High-efficiency filtration significantly improves indoor air quality in:

• Hospitals

•  Labs

•  Pharma and food industries

This supports better health and productivity.

🔹 How HEPA Filters Elevate HVAC Systems

✓ Regulatory Compliance

In cleanroom validation (HVAC), HEPA filters are mandatory to meet ISO 14644-1 and GMP guidelines. Their integrity is essential to maintain the required cleanroom classifications.

For official ISO 14644-1 guidelines, refer to the ISO website.

✓ Consistent Particle Control

HEPA filters in a cleanroom maintain a controlled particle environment across validated zones. This is critical for preventing contamination during:

• Drug manufacturing

•  Medical device production

•  Semiconductor processes

✓ Pressure drop due to clogged HEPA filters

Another cleanroom HVAC issue can be resolved using Clean filters to maintain pressure differentials by balancing airflow resistance—essential for keeping clean zones isolated from less clean areas.

✓ Data-Driven Validation

HEPA filter in AHU testing (via PAO testing, pressure drop monitoring) provides quantifiable data for cleanroom certification and audits, which is key in HVAC services.

If a clogged or blocked HEPA filter is installed or left unchanged in a cleanroom, it can have severe impacts on both the performance and energy efficiency of the HVAC/AHU system. Here's a breakdown of the consequences:

🔴  Reduced Airflow to the Cleanroom

• HEPA filters offer high resistance by nature, and a clogged one will restrict air even more.

• This leads to reduced air changes per hour (ACH) — crucial for maintaining cleanroom classification.

Result: Contaminant levels increase, compromising the cleanliness class (e.g., ISO Class 7/8).

🔴 Increased Pressure Drop

• A clogged HEPA creates a higher pressure drop across the filter.

• The fan/blower in the AHU has to work harder to overcome this resistance.

• If the system wasn't designed with enough margin, airflow can drop drastically.

🔴  Fan and Blower Impact

• Increased power consumption: The AHU fan motor draws more current to maintain airflow.

• Overheating or motor burnout: Prolonged overloading can damage the motor or blower.

• Noise levels may also increase due to the strain.

🔴  Energy Inefficiency

• HVAC systems already consume a large portion of cleanroom energy (up to 50–60%).

• A blocked filter can increase energy use significantly — sometimes by 20–30% or more, depending on system type and control strategy.

🔴  Unstable Room Pressure

• If the supply airflow is reduced due to the blockage, room pressurization will fluctuate.

• Positive pressure rooms may fail to prevent contamination from adjacent lower-class areas.

 🛠 Recommended Action:

• Monitor pressure drop across HEPA filters using Magnehelic gauges or sensors.

• Replace filters when the pressure drop exceeds recommended limits (often ~250–500 Pa).

• Consider pre-filters to prolong HEPA life.

### 🛠️ Final Thought: Don’t Let a Filter Fail Your Facility

A clogged HEPA filter isn’t just a maintenance issue—it’s a threat to cleanroom integrity, HVAC performance, and compliance.

➡️ Need help with HEPA filter monitoring or replacement? [Contact our HVAC experts today sales@tescroom.com](#)!