Air handlers in the garage: Leak potential too risky?

June 1, 2000
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It’s no secret that residential air handlers tend to leak. At times, potentially toxic air contaminants in their vicinity may be sucked into the system and spread throughout the living spaces they serve.

In a nutshell, that’s the issue and dilemma facing hvac contractors and installers as they attempt to balance ease and economy of installation with efficiency and safety for their customers.

Eighteen deaths have occurred in Florida alone since 1994, The St. Petersburg Times reported in mid-October. Air handlers sucking in CO from attached garages are suspected culprits in many cases. Not long ago, five people died in a Lantana home “while a car sat running in the garage,” the online version of a Daytona Beach newspaper reported.

Ban protested

Early this year, the committee that writes residential ventilation standards for the American Society of Heating, Refrigerating and Air- Conditioning Engineers (ASHRAE) proposed that air handler installations in attached garages be banned, and that carbon monoxide detectors be mandatory in new residential construction.

That proposal didn’t advance to the public review stage, however, because the National Association of Home Builders (NAHB) and the American Gas Association (AGA) protested the restriction on air handler location, according to Max Sherman, chairman of the ASHRAE committee and a ventilation expert working for the Lawrence Berkeley National Laboratories, Berkeley, CA.

“ASHRAE told us to work with them,” Sherman told The News.

The committee met again in September and removed the prohibition on air handler installation in attached garages. However, the mandatory installation of carbon monoxide detectors remains in the proposed standard. That draft has been approved and will be released this winter for public review, Sherman said.

The argument advanced by those opposed to the restriction on air handler installation in attached garages was that if carbon monoxide detectors were mandated, the issue was covered, he said.

“But carbon monoxide isn’t the only thing the air handler might suck in from your garage,” Sherman countered. “There are lots of things people have that might add unwanted fumes to the air supply.”

“The garage is a poor location for the air handler,” stated an article in Energy Source Builder, crediting training conducted by the Bonneville Power Administration, “because return-side leaks can pull auto exhaust and fumes from stored chemicals into the house. Typically, more air leakage occurs near the air handler than in the ducts.”

For several years, Miami-Dade County, FL, has mandated that air handlers in garages be contained in sealed closets to reduce the risk of such infiltration. Jim Herritage of Energy Auditors, Mount Pleasant, SC, and education coordinator for the South Carolina Electric Heat Pump Association, concurred that “many air handlers . . . are very leaky. With the blower mounted in the supply side of the cabinet, most of the air handler would still be under a negative pressure, sucking in unconditioned air through the liquid, suction, and condensate lines’ access ports.”

Take a look at sealing ducts

“Installing air handlers in garages is common practice in many parts of the country,” commented Peter G. Engle, P.E., Almost Home, Rumson, NJ. The company provides home and building inspection and engineering consulting services for the owners or buyers of new and old commercial and residential buildings.

“Like many questionable practices, it does not always result in death of the occupants of the home,” Engle said. “The practice does cause negative health effects often enough to be a concern, but I’m not sure that banning the practice is the right approach.

“The fact is, air handlers move air,” he continued. “Because they do this, they have the potential to cause pressure imbalances within the house. Pressure imbalances drive pollutants from one location to the other.”

His answer: Install balanced air handlers and ductwork systems and seal the ductwork. “Then it doesn’t matter where the air handler is located,” he said.

Engle stated that “One of the dirty little secrets that the hvac industry would like to forget about is that sealing the ductwork is already required by code in most of the country.”

Common sense dictates that CO from attached garages can seep into homes and kill people, whether or not the air handler is located in the garage, Engle said.

“All you need is a slight depressurization of the inside of the house with respect to the garage, and a pathway from the garage to the house, and you’ve got a CO poisoning problem,” he said.

The answer, again, is to seal the ductwork and balance airflow. His suggestion? Obey the codes that are probably already in place.

“It’s kind of like what the gun people say,” Engle summarized: “Don’t pass new laws; enforce the current ones.”

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