After floodwaters submerge

a building’s HVAC system, the

process to determine whether to

repair or replace it requires a plan

that is partially governed by

standards, partially by experience.

B y R . G . ( B o B ) B a k e R

[Editor’s Note: Baker’s onsite account was left in first-person to maintain the integrity of the post-flood inspections he per-formed to the HVAC systems discussed in this article.]

In mid-May 2010, a devastating flood—coined a 1,000-year flood—hit the city of Nashville, TN, and surrounding ar-eas of middle Tennessee. It was a significant disaster that

claimed more than 30 lives; caused more than $1 billion—and still counting—in damages; closed several entertainment and shopping complexes, including the Opryland Hotel, throwing thousands out of work; and created financial ruin for countless families who were living in areas not eligible for flood insurance.

This was a vivid event, because friends of mine in the Nashville music industry were affected and asked me to help in the recovery. In addition to bringing a donated pallet of cleaning, antimicrobial and odor-control products from BBJ Environmental Solutions, much of my time was spent working

at the Soundcheck complex—a group of warehouses where artists prepare for their tours and store props, supplies, and equipment—that endured the loss of high-end electronics and musical instruments running into the hundreds of thou-sands of dollars.

In addition to helping figure out how to decontaminate and restore irreplaceable instruments—sorting out what could be salvaged and readied to take on the road—I also worked with several facilities’ flooded HVAC systems. The experience reminded me of important considerations and the impact floods have on these systems, and the proper restora-tion practices that need to be made to both the equipment and air-distribution system.

Where to beginThe Institute of Inspection Cleaning and Restoration Certification—a Vancouver, WA-based non-profit certifica-tion organization that monitors educational programs and

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Floods and

HVAC systems

once the waters receded after the May 2010 flood in Tennessee, cleanup efforts began in several locations, in-cluding the Soundcheck complex shown here. Water con-tamination and mold growth in HVaC systems following a flood requires diligent cleaning and testing procedures.

standards for the inspection, cleaning and restoration ser-vice industries—has published two standards that provide guidance for restoring facilities after a flood or mold con-tamination (the latter of which almost always follows the former): IICRC S500 Standard and Reference Guide for Professional Water Damage Restoration; and the ANSI/IICRC S520 Standard and Reference Guide for Professional Mold Remediation. Both standards have sections dealing with resto-ration of HVAC systems.

The introduction to the HVAC chapter in the S520 Ref-erence Guide points out many of the issues clearly: “HVAC Systems have a major impact on controlling the conditions that lead to condensation films. The design, installation, operation and maintenance of HVAC systems are impor-tant factors in mold control. In addition, mold growth from other causes can be carried to the interior of HVAC system components where it accumulates and degrades the opera-tion of the system. When operation is affected this may re-sult in poor environmental control that allows more wide-spread condensation films to form. This condition can lead to the spread of contamination by the system and increase the scope of the mold problem by dispersing contaminants throughout a building.”

Many experts in the field consider HVAC systems to be a major factor when managing the outcome of floods, espe-cially the resulting mold growth. It is important that HVAC techs understand the impacts a flood can have on the sys-tem and its components, and the most appropriate way to approach the task of supporting those who are attempting to restore an entire facility.

From the ground, upThe IICRC standards offer valuable guidance in such a where-to-start mess that a flood creates. There are a num-ber of things that should be addressed—and in a certain or-der—in the event of a flood. In addition to immediate dam-age control, techs should keep the following in mind.

Damage to the electrical supply—As is often the case in a flood, the basements of most facilities fill with water, which is often the location for the electrical switch panels,

transformers and grid for the entire establishment. In the re-cent Nashville flood, this was the case for a large night club called Cadillac Ranch. Despite the fact that there was no wa-ter intrusion into the main floor of the club, safety consider-ations required that all of these components be replaced be-fore the club could reopen. The first step should always be to evaluate and repair the electrical supply before attempting to restart the HVAC system.

In both the Cadillac Ranch and Soundcheck cases, the

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HVAC systems Photo courtesy of the author.

an unexpected post-flood problem sprang up at the Soundcheck complex—snakes. Both venomous and non-venomous snakes seeking refuge from the water were patiently waiting for cleaning crews in filing cabinets, drawers and other seemingly innocuous storage areas.

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risk was so high that all electric service to the buildings was discontinued by local authorities until inspection and repairs could be made. Emergency generators were needed to supply power and lighting. This is normal in most jurisdictions and is one of the realities remediation contractors and/or owners must deal with.

Bacterial and viral contamination—It should be as-sumed that flood water contains sewage and other contami-nants. Therefore, steps must be taken to kill or remove any disease-causing (pathogenic) organisms before attempting to restore the system to operation. Generally, HVAC system cleanliness is evaluated visually using experience and judg-ment. The National Air Duct Cleaner’s Association Standard ACR 2006 includes a description of a vacuum test that is of-ten used during the inspection process. One of the Nashville locations I visited was a public relations firm where the base-ment was flooded with sewage backup. The air handler and sections of supply and return ducts were under water. We had to use a broad spectrum disinfectant to destroy any bacteria that might have been left in the flooded components before we could do any other work.

In this case, be sure that the disinfectant that you choose has been registered by the U.S. EPA for safe use in HVAC systems. Disinfectants are normally applied in air ducts using manual or automated (robotic) spraying equipment; the appli-cation always must be consistent with manufacturer’s direc-tions. Contact times for disinfection vary and product litera-ture should be consulted for the product used.

Overall system function—IICRC standards require a complete engineering evaluation of the HVAC system to assure that flooding has not damaged the system in a man-ner that prevents it from operating properly. In the case of one Nashville facility that I inspected, the air-handler fan motor contained moisture that could have caused overheat-ing if it had been started up before being completely dried or replaced. Unfortunately, it can be difficult to determine if electrical components are sufficiently dry. Judgment and ex-perience with drying techniques is important here. The best results are obtained when experienced drying contractors and HVAC technicians work as a team.

Residual wetting impact—Insulation, lined ducts and flex ducts may not perform well after being soaked with wa-

ter; even if thoroughly dried. Moisture can compromise in-sulation efficiency so that it will not achieve satisfactory performance. Even more serious, porous materials such as insulation may retain bacterial, fungal or viral contamination even following careful drying (in accordance with existing industry best practices). It is always advisable to consider replacement of any porous materials such as insulation or duct lining that has been dampened by flood water. IICRC Standards S500 and S520 both address the issue of porous materials in HVAC systems and provide specific guidance for replacement versus cleaning. Normally these require that po-rous materials be discarded and replaced.

HVAC system hygiene—Any time there has been a flood, there is a high likelihood that the system has be-come contaminated even if flood waters did not actually wet system components. Contamination from involved areas can easily be carried to the system through the air and contami-nate interior surfaces within the system. A complete cleaning of the system including air handlers, ducts and other com-ponents on the air side should always be considered. This is especially important if the system has operated before other parts of the facility were remediated and cleared as safe. Of-ten, it is advisable to treat the system following cleaning with an antimicrobial designed to inhibit the possibility of future growth in case spores or live organisms were missed during the cleaning.

As long as a system has at least a partial refrigerant charge, it can be assumed that internal pressure has been sufficient to keep water out of the refrigeration loop. In any case where total refrigerant charge has been lost, it should be assumed

Photo courtesy of the author.

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that the system is contaminated with moisture and the same procedure should be followed that is used with a compressor burnout failure. It is possible that system components may have become totally submerged before electrical supply was shut off (espe-cially if the system does not include ground fault protection).

HVAC system restart—There is no “magic” sequence in restarting a system. It is really dependent on the system’s design and beyond the scope of this article. What is more important is the thoroughness of the system in-spection, cleaning and repair/replace-ment of components where indicated. Following a flood, the best guidance, especially with electrical compo-nents, is: when in doubt, replace.

Roles in remediationA flood brings many important con-siderations for HVAC technicians. When a remediation strategy is planned, HVAC system professionals are vital members of the team that is assembled to assure that a facility is restored to operation in a manner that protects occupants, reduces the likeli-hood of future problems and assures that HVAC systems will continue to operate in a manner that reduces the probability of future problems.

R.G. (Bob) Baker is the Owner of BBJ Environmental Solutions (a supplier of cleaning, antimicrobial and odor control products for HVAC-system mainte-nance and water/mold remediation) in Riverview, FL. In addition to manag-ing BBJ, he provides HVAC design, operations and maintenance advisory services to facility managers and oth-ers. He is a Fellow Member as well as a Distinguished Lecturer of ASHRAE.

Photo courtesy of the author.