Power Struggle

KitchenAid

There’s a power struggle going on in kitchen ventilation. Manufacturers of range hoods have turned up their maximum blower speeds to the point where a few residential models now have enough power (1,800 cubic feet of air per minute [cfm]) to clear the fumes and vapors from any high-powered electric or gas range that operates at full blast.

But ventilation experts have become increasingly concerned in the past 2 years that range hoods’ high-powered blowers are sucking too much air from homes. So range hood manufacturers are refining their products, and some are developing make-up air systems to make up for, or replace, the air that a range hood removes from your home.

It’s a confusing tug-of-war for consumers, who have been told for years that more power equals better when it comes to range hoods. What’s worse is that if your home is new or has been remodeled, shopping for a range hood also might mean shopping for an adequate make-up air system. In most cases, this requires consulting with a contractor and paying for the installation of pipe and ductwork.

VENT AND MAKE UP. Three years ago in suburban Minneapolis, Shady Oak Distributing, like dozens of distributors elsewhere, recommended that customers buy a range hood that had a maximum blower speed of at least 600 cfm to vent the air that’s produced by high-Btu gas cooktops or ranges. Shady Oak still makes that recommendation. But now the company must remind customers that Minnesota law requires customers to buy a make-up air system (a rooftop-mounted vent that brings in air from the outside) when they buy a range hood that has a speed of 300 cfm or higher.

The concern is that because houses are becoming “tighter” (meaning better insulated and less drafty to improve energy efficiency), exhausting too much air from a house through a powerful range hood could create negative pressure inside the house, says Paul Raymer, who is an expert on residential ventilation issues.

A house that has negative pressure, or is depressurized, can suck combustible and deadly gases down the chimney, particularly during the winter when windows and doors are shut and sealed, Raymer says. In cold northern climates, such as Minnesota’s, depressurization has resulted in fires, explosions and carbon monoxide inhalation, says Jim Fitzgerald, who is the director of building services for Conservation Services Group, which advocates energy efficiency in homes.

Bringing air back into your house through a make-up air system can be as simple as having an installer add a $200 pipe. But depending on the climate and the temperature, the air that’s pulled back into your house must be heated and cleaned, says Brent Matson of Shady Oak. Installing such a system could cost as much as $5,000.

Welcome to the reality of buying a range hood in Minnesota in the past 3 years. Canada and a handful of cities in California, Colorado, Maine and Wisconsin have adopted similar building codes. Building Performance Institute (BPI), which develops technical standards for home performance in North America, and Home Ventilating Institute (HVI), which is a trade association for ventilation manufacturers, agree that similar building codes will be required in other states and cities in the next 5 years.

“I would think that in any of the northern states that are in the colder environments, you’re going to see that law,” says Matt Avery of Faber, which is a range hood manufacturer. You even might see it appear in a few southern states, he says.