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This article describes a field observation of a fire-damaged heat recovery ventilator unit found by Minnesota home inspector Roger Hankey.
The inspection suggests that the root cause of the fire at this HRV was the collapse of an air filter that was drawn into the fan assembly. Remarkably the home owner's report that the heat recovery ventilator was in working order suggests that the hazard and equipment failure had remained un-discovered for a long time.
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Field report of Heat Recovery Ventilator HRV Fire / Overheat Damage
Mr. Hankey notes: The home seller's disclosure indicated the HRV was in working condition. Our field observation found that this was not the case. [Click to enlarge any image]
This was a VanEE heat recovery ventilation unit built & installed circa 1987. That dates this device as having been manufactured before the units made in 1991-2001 and cited in
There you will read that Venmar made heat recovery ventilator systems that were sold under multiple brand names besides VanEE, including Venmar, Broan - Guardian, Conformax, Nutone, Bryant Carrier - Standard, Carrier, Bryant - Payne Day & Night, Heil, Sears, York, Rudd Protech - Weatherking, and Rheem. Note that since not every HRV sold by those companies is subject to the recall, you'll want to check the article cited above.
Notice clogged collapsed intake filter (photo above right). I attribute the motor burn out to the clogged filter.
Watch out also: for a collapsing or collapsed or improperly-sized or supported air filter in any heat recovery ventilator or other air handling equipment. An improperly-installed or designed air filter that collapses and becomes drawn into the blower assembly can cause the motor to overheat and may cause a building fire. These hazards are present in any HVAC system that incorporates a blower fan and air filter in a position where a failed or damaged filter or other object could be drawn into moving parts such as the fan assembly.
Roger Hankey is principal of Hankey and Brown Inspections, Winter Park, CO. Mr. Hankey is a past chairman of the ASHI Standards Committee and served in other ASHI chapter and national leadership roles. Mr. Hankey is a National Radon Proficiency Program certified measurement professional and a Level II infrared thermographer. Contact Roger Hankey at: 970-393-6604 - rogerhankey47@gmail.com . Website: www.HankeyandBrown.com
Mr. Hankey is a frequent contributor to InspectAPedia.com.
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In addition to any citations in the article above, a full list is available on request.
Roger Hankey is principal of Hankey and Brown Inspections, Winter Park, CO. Mr. Hankey is a past chairman of the ASHI Standards Committee and served in other ASHI chapter and national leadership roles. Mr. Hankey is a National Radon Proficiency Program certified measurement professional and a Level II infrared thermographer. Contact Roger Hankey at: 970-393-6604 - rogerhankey47@gmail.com . Website: www.HankeyandBrown.com
Mr. Hankey is a frequent contributor to InspectAPedia.com.
ASHRAE, Handbook, A. S. H. R. A. E. "Fundamentals." American Society of Heating, Refrigerating and Air Conditioning Engineers, Atlanta 111 (2001).
ASHRAE, Handbook, A. S. H. R. A. E. "HVAC systems and equipment." American Society of Heating, Refrigerating, and Air Conditioning Engineers, Atlanta, GA (1996).
DeGregoria, Anthony J., and Thomas J. Kaminski. "Integrated heat recovery ventilator HEPA filter using a HEPA filter material regenerative heat exchanger." U.S. Patent 6,289,974, issued September 18, 2001.
Kovesi, T., C. Zaloum, C. Stocco, D. Fugler, R. E. Dales, A. Ni, N. Barrowman, N. L. Gilbert, and J. D. Miller. "Heat recovery ventilators prevent respiratory disorders in Inuit children." Indoor Air 19, no. 6 (2009): 489-499.
Linden, Paul F. "The fluid mechanics of natural ventilation." Annual review of fluid mechanics 31, no. 1 (1999): 201-238.
Markowski, Walter J., and Albert J. Marron. "Total heat energy exchangers." U.S. Patent 4,093,435, issued June 6, 1978.
Mentuch, Stephen. "Heat recovery ventilator." U.S. Patent 4,742,957, issued May 10, 1988.
Olmstead, Richard W., and Douglas B. Wicks. "Heat recovery system." U.S. Patent 5,002,118, issued March 26, 1991.
Warner, Jill A., Jeanette M. Frederick, Trevor N. Bryant, Christine Weich, Gary J. Raw, Colin Hunter, Frank R. Stephend, Donald A. McIntyre, and John O. Warner. "Mechanical ventilation and high-efficiency vacuum cleaning: A combined strategy of mite and mite allergen reduction in the control of mite-sensitive asthma." Journal of allergy and clinical immunology 105, no. 1 (2000): 75-82.
Air-to-Air Heat Exchangers for Healthier Energy-Efficient Homes, Kenenth Hellevang, PH.D., P.E., Extension Engineer, and Carl Pederson, Energy Educator, North Dakota State University, AE-1393, NDSU Extension Service, North Dakota State University, Fargo ND 58108, March 2009. Web search 02/04/2011, original source: http://www.ag.ndsu.edu/pubs/ageng/structu/ae1393.pdf, reproduced for non-commercial use, with permission.
DUST, HVAC CONTAMINATION STUDY An Investigation of Indoor Dust Debris Blamed on a Heating/Cooling System Reveals Carpet Dust
National Fuel Gas Code (Z223.1) $16.00 and National Fuel Gas Code Handbook (Z223.2) $47.00 American Gas Association (A.G.A.), 1515 Wilson Boulevard, Arlington, VA 22209 also available from National Fire Protection Association, Batterymarch Park, Quincy, MA 02269. Fundamentals of Gas Appliance Venting and Ventilation, 1985, American Gas Association Laboratories, Engineering Services Department. American Gas Association, 1515 Wilson Boulevard, Arlington, VA 22209. Catalog #XHO585. Reprinted 1989.
Building Pathology, Deterioration, Diagnostics, and Intervention, Samuel Y. Harris, P.E., AIA, Esq., ISBN 0-471-33172-4, John Wiley & Sons, 2001 [General building science-DF] ISBN-10: 0471331724
ISBN-13: 978-0471331728
Building Pathology: Principles and Practice, David Watt, Wiley-Blackwell; 2 edition (March 7, 2008) ISBN-10: 1405161035 ISBN-13: 978-1405161039
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Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: info@carsondunlop.com. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Carson Dunlop Associates provides extensive home inspection education and report writing material. In gratitude we provide links to tsome Carson Dunlop Associates products and services.