Fouling of evaporator coils occurs for several reasons. Facilities managers, concerned about providing a safe and productive work environment, prevent this through routine HVAC maintenance. For example, air filter replacements and coil cleanings help the system circulate clean air. Before we address the solutions, let’s explore some of the reasons for fouled HVAC coils.
Filter Bypass and Fouled HVAC Coils
The main cause of fouled HVAC coils occurs as a result of filter bypass. In this case, tiny particles travel through gaps in the filter. This allows them to enter into the ductwork and then into the place of business. Debris that skips the filtering process can build up and foul the HVAC coils. Therefore, one of the most important considerations in HVAC preventive maintenance is selecting the right filter. Filter bypass also occurs when the AHU cabinet is not sealed properly or has been breached. In addition to providing a healthier work area, reducing filter bypass reduces energy costs as well.
Choosing the Right Filter
A higher-rated filter upgrade results in cleaner air. For instance, a MERV-rated filter would increase the system’s efficiency in stopping particulates from moving throughout a building. Pathogens including bacteria, mold, and viruses are included in this. Using a filter with a higher rating affects how well the HVAC system performs.
What Do HVAC Coils Get Fouled With?
Any airborne particle contributes to the fouling of the HVAC coil. This is true in school buildings, government buildings, medical facilities, and commercial businesses. Airborne particles include dirt, pollen, soot, carbon, and mold. Dust is another contributor, the majority of which consists of shed human skin cells.
Different industries produce different contaminants. For example, a manufacturing facility may produce metal flakes and manmade fiber. Mixing ingredients, such as flour, are common in food production. The main categories of these contaminants are bioaerosols, soils, dirt, and debris. Water intrusion from both inside and outside a building also contributes to contamination.
How Does Coil Fouling Affect Performance?
When contaminants mix with the condensation collected on the coil, mold results and leads to fouled HVAC coils. Fouling and mold growth impedes the appropriate flow of air across and through the fins. This also insulates the fins and restricts heat transfer. A thin layer of debris may also cover the coil thus obstructing airflow. This might prevent the system from drying out the air, which would intensify any contaminants already present and make them a food source for microbial development. Dust and debris also affect the drain pans and insulation resulting in foul odors. Allergic reactions and more serious respiratory issues may also result from poor ventilation indoors.
The PURE-Steam Coil Cleaning Method
The Pure-Steam method offered by WTI Pure Air Control Services is effective in restoring fouled HVAC coils. HVAC coil cleaning is an innovative method to restore, not only the evaporator coils but the entire interior of an air handling unit (AHU). In fact, this method restores the system to near-factory specifications of performance and cleanliness. It is a comprehensive indoor air quality and energy-efficient solution that is the only Green Clean Institute-certified process in North America.
PURE-Steam cleans the coils and AHU at temperatures as high as 350° F, thus eradicating bacteria and fungi (mold), and removing allergy triggers and musty odors. Additionally, PURE-Steam cleans at pressures of up to 350 psi, forcing dust and other material through the coil to enhance airflow and Delta P (pressure) for significant operating savings. The recommendation for this method of preventive maintenance is annually or twice a year.
Cleaning fouled HVAC coils takes four steps. The first is the preparation of the system which includes analyzing system specifications as well as shutting down the unit. Next, trained service technicians perform a proprietary Coil Cleanliness Verification Test (CCVT). The cleaning of the system follows with a Measurement & Verification (M&V) Report as the last step in the process.
Learn More About HVAC Coil Cleaning
For more information on how WTI Pure Air Control Services helps building managers keep HVAC coils from fouling, contact us today at 1-800-422-7873 or email us here.