Alan C. Veeck, CAFS – IEQ & Filtration plus What is the Wells-Riley Equation?

Air Date: 3-6-2015 | Episode: 359

This week on IAQ Radio we welcome a respected industry veteran Mr. Alan Veeck, CAFS, NCTII…

Full Description: 

This week on IAQ Radio we welcome a respected industry veteran Mr. Alan Veeck, CAFS, NCTII. Al is Executive Director of the National Air Filtration Association (NAFA) which is headquartered in Virginia Beach, Virginia. He is a 1969 graduate of Butler University in Indianapolis, IN, with a degree in Business Adm. He began his 3rd career in the air filtration business in 1985 with Butler UniversityTidewater Air Filter as Vice President of Sales. While with Tidewater, Al was elected President of the National Air Filtration Association (NAFA) in 1999. He also served and worked on the committee that wrote the first book on air filtration, NAFA Guide to Air Filtration, and was part of the first group of NAFA members to pass the national accreditation exam to become a NAFA Certified Air Filter Specialist (CAFS). Mr. Veeck also worked on the committee to write the second text for NAFA entitled, Installation, Operation and Maintenance of Air Filtration Systems. When he retired from the filter industry in 2002, NAFA was searching for someone to manage the national trade association and asked Al to take the position. With prior experience in association work, Al accepted and has been NAFA’s Executive Director ever since. He is a member of the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) since 1985 and headed ASHRAE TC2.4 of which he is still a voting member, and a member of International Facility Management Association (IFMA) since 1998. He is the recipient of both the NAFA Distinguished Service Award and the ASHRAE Distinguished Lecturer and Distinguished Service Award. LEARN MORE about IEQ and filtration including a review of the recent NAFA document titled “HVAC filtration and the Wells-Riley approach to assessing risks of infectious airborne diseases” this week on IAQ Radio!

ZMan’s Blog:

Clean air is good health

Alan C. Veeck, Executive Director of the National Air Filtration Association. NAFA has done some great work on demonstrating the value and importance of improving filtration. Alan has a knack for simplifying complex concepts.

Gold NuggetsNuggets mined from this week’s episode:

  • Members of the National Air Filtration Association are filter manufacturers and distributors. The NAFA website is:
  • What’s new in filtration? Popularity of improved electrically enhanced filter media made nonwoven textile that attracts particles with opposing charges like a magnet.
  • “Paper like” micro-glass fibers used in MERV 14-15 filters is similar to the media used in HEPA filters. Mini-pleated type MERV-14-15 filters now more dominate in the commercial market. The acronym MERV is short for: Minimum Efficiency Reporting Value.
  • Highly efficient MERV 11-MERV 14 filters are different than HEPA filters. Pressure drop across clean MERV 13-15 filters .30” inches H2O. Pressure drop across a clean HEPA filter is .8-1” inches H2O.
  • Different test procedures are used ton HEPA filters and MERV filters. HEPA filters remove 99.97% of all. Particles of 0.3 micron size act like gases. MERV filters remove 99%+ of different sized particles. A 99% filter tested to the ASHRAE Standard might achieve 95% using the Mil. Std. 282 (HEPA test).
  • Air filtration is a challenge in larger new homes with open floorplans where particles can settle before being captured. Strategies for use in these homes include: capturing contaminate at the source (kitchens) with exhaust and filtration, using high efficiency HEPA filtered vacuum cleaners, running the HVAC fan continuously and purchasing small air filtration units for problem areas and bedrooms. Running HVAC on fan continuously also helps reduce air temperature stratification.
  • Reasons for air filters not performing well include: wrong filter selection for application, incorrect installation or installation of damaged filters, air bypassing filters due to gaps in filter frames, etc.
  • In commercial buildings HVAC rooms often get cluttered with cleaning compounds and chemicals. Vapors from stored materials may be drawn into the HVAC system and circulated throughout the building. Dirty coils may become unintended air filters. Dirty coils have been shown to equal about a MERV 8 filters.
  • Condensate pans often don’t drain due to design and construction defects and location on negative side of the system. UV radiation directed onto coils and condensate pans have proven to be effective in controlling biofilm accumulation.
  • The answer to the questions: when do you empty a wastebasket and when do you change an HVAC filter is the same? When it’s full. It’s recommended that residential air filters be changed every 45-60 days. Fiberglass air filters are no longer recommended for residential use, minimum MERV 6 filters are now recommended.
  • The MERV listing on filters indicates that the filter has been tested. Filters without MERV listings haven’t been tested and should not be purchased.
  • Gaps in residential HVAC systems smaller than the thickness of a playing card are not a problem while larger gaps waste energy. Proper filter fit and seal is important in all applications. 1” thick filters are most common in residential applications with a shift to 2” thick in larger higher velocity HVAC system. Commercial air filters incorporate gaskets. So should residential.
  • Air duct design and component selection is critical to particle removal effectiveness.
  • Air doesn’t flow like water, air can flow in any direction. Soiling on the backside of fan blades is caused by air turbulence. Turning vanes are used in commercial HVAC systems to assist air movement around corners and reduce turbulence.

Healthcare facilities are hard to keep clean: 

  • Wells Riley equation is a graph which shows that the more outside air brought into a facility the less chance of spreading contagious disease. See Dr. Brent Stephens’ work:

  • ASHRAE promotes increasing ventilation to lower infection risk. Outside air isn’t fresh, it contains particulate and gases. Increasing ventilation is expensive because the added outside air must be filtered and tempered. The NAFA approach of improving filtration saves energy. Dr. Jenifer Wagner’s approach is to Merge Cleanroom Techniques and Filtration into the Operating Room, see:
  • Advocates the addition of overhead HEPA filter modules in operating suites and isolation/protective rooms
  • Do no harm when cleaning and maintain HVAC systems. Isolate HVAC units, don’t re-entrain particles within unit or facility. Workers should wear full face respirators with HEPA filters.

Alan Veeck’s last words: 1) nanofibers are promising, 2) people want to breathe clean air and 3) clean air is good health.

Today’s music: Dust Pneumonia Blues by Woody Guthrie, YouTube

ASHRAE’s solutions for improving IAQ always seems to be adding more ventilation, I really like NAFA’s approach of improving filtration.

Z-Man signing off


Question: What does the acronym MERV stand for?

Answer: Minimum Efficiency Reporting Value