May 10, 2020 Keep Your HVAC System In As-Built Condition With UV-C
Keep HVAC Operating at Peak Performance
Many factors can impact a building’s environmental performance and the consumption of energy, water and materials. Manufacturers of building systems design performance around a specific, optimal condition. Over time, these performance standards will deteriorate if nothing is done to preserve the original “as-built” condition.
This is especially true for HVAC systems, which become increasingly less efficient as mold, biofilm and other organic compounds accumulate on cooling coils, drain pans and other surfaces, causing:
– Airflow restrictions (lost heat transfer), which deteriorates energy performance.
– Odors and the spread of respiratory irritants, pathogens and allergens.
– Shortened equipment and material life and increased maintenance.
One technology that helps to reverse this loss in HVAC efficiency is Ultraviolet-C (UV-C) lighting.
In a recent article published by HPAC Engineering Magazine, the late Forrest Fencl, co-founder of UV Resources and ASHRAE Fellow, examines how UV-C energy keeps HVAC equipment operating at peak performance.
For new installations, the UV-C wavelength maintains a clean coil’s condition; and for existing applications, UV-C energy degrades organic materials that have deposited on coil fin and tube surfaces. As a result of this cleaning action, a coil’s “open area” remains at ‘as-built’ parameters or returns to the original, designed performance standards. The pressure drop and velocity of the air between coil fins is optimized, while fin and tube surfaces are kept clean to maximize system heat-exchange efficiency and rate.
Many original-equipment manufacturers believe that regularly-maintained UV-C technology could contribute to maintaining as-built capacity for the life of a system.
Persistent HVAC performance translates to:
- Improved Indoor-Air Quality (IAQ)
UV-C helps to maintain or, in a retrofit, significantly improve IAQ. The application of UV-C prevents the formation and reduces the spread of several categories of organisms that can affect modern air-handling systems. These include pathogens (viruses, bacteria and fungi, which can cause a range of diseases), allergens (bacteria and mold, which can cause allergic rhinitis, asthma, humidifier fever and hypersensitivity pneumonitis) and toxins (endotoxins and mycotoxins, which can cause a variety of toxic effects, irritation and odors).
- Greater Occupant Comfort
With coils kept clean, heat-exchange efficiency and rate are maintained at as-designed values. Furthermore, with microbial growth and transfer prevented, the air serving occupied spaces is not contaminated by foul-smelling bio matter.
UV-C is the Superior “Persistence-Restoring” Option
Although there are other methods of keeping HVAC systems persistently performing, they carry some serious downsides. Vapors from cleaning agents can contribute to poor air quality, chemical run off contributes to ground water contamination and mechanical cleaning can reduce component life. Furthermore, the system’s performance can begin to degrade shortly after a cleaning application, as microbial deposits reappear or reactivate.
The results and concerns here are not always obvious. Coil cleaning does not get the coil perfectly clean, regardless of the amount of water or chemical agent used. Following each cleaning, contaminants return and additional organic material is deposited. Additionally, coil-cleaning chemicals contaminate drain waterways and air streams, which are not consistent with the green-building theme, or acceptable IAQ practices.
UV-C Reduces Maintenance Costs
The use of UV-C in HVACR equipment has been shown to reduce maintenance and associated costs. According to Chapter 60.8 of 2011 ASHRAE Handbook—HVAC Applications, “Potential advantages of UV-C surface treatment includes keeping surfaces clean ‘continuously,’ rather than periodically, restoring fouled surfaces, with no use of chemicals, and lower maintenance cost and, potentially, better HVAC system performance.”
UV-C is thus the best option to keep a building’s HVAC system persistently operating at the intended as-built condition.
Owners and operators of buildings have many worries on their plates; keeping coils and drain pans clean does not have to be one of them.