Heat recovery ventilators clean air, save energy

New on the "green" horizon is an exotic machine that freshens your air and makes your home a nicer place to live, while saving you energy.

It's called a heat recovery ventilator (HRV) and it efficiently gets rid of fumes from cooking, bathrooms, cosmetics and carpets while helping heat or cool a home.

As a result, you save enough energy to certify your home as green and qualify you for Energy Star and Earth Advantage programs, so you get rebates from the Oregon Energy Trust, as well as tax credits through the Oregon Department of Energy, says Bernie Gordon, who sells the devices with Spring Air of Jacksonville — and does the paperwork for the credits.

"It's green because it reduces your carbon footprint in two big ways — saving energy and lowering your impact on the energy infrastructure of the U.S.," he says. "It's a sustainable product that makes your home last longer."

In regular homes, people count on kitchen or bathroom fans to bring in fresh air and the effect, Gordon says, is that they rely on leaks, pulling outside air in through cracks around doors, windows and in walls, stressing those gaps and even leading to moisture that can create mold inside walls.

What the heat recovery ventilator does is exhaust the stale indoor air, but before it does, it sends that air through a box where (for heating) it robs the old air of most of its heat, transferring it to incoming fresh air, he says.

Even so, few homeowners or builders know about HRVs — and think they get plenty of fresh air from people walking in and out the front door.

"Generally, the HRV is an air quality issue for high-end homes and people feel they get enough new air through kitchen and bathroom fans," says Rick Milne of S&S Heating and Air Conditioning in White City.

"It's ideal for newer homes, which are real tight. You can use them to get rid of air full of cooking smells, perfumes and odors from carpeting." HRVs are not cheap, they cost about $2,500 installed, including the ducting — but they do add to the resale value of homes, allowing you to market it as a "green" building.

When cooling, the HRV does the same thing in reverse, transferring coldness from outgoing air molecules onto the incoming air. You can also buy devices that transfer desired humidity. These are called ERVs — energy recovery ventilators.

The air of a house should be exchanged at the rate of .35 exchanges an hour and not less than 15 cubic feet per minute per person — and an older home will, because of leaks, exceed that, says the August 2000 issue of Popular Mechanics . It adds that an electrostatic filter working with forced air heating will help exchange air but won't remove excess moisture, stale air or pollutants in the air.

An HRV handles all these problems and saves about 80 percent or more of the heat in outgoing air, says Gordon.

The HRV can easily be added during construction or remodeling, but might be hard to fit in older homes, especially if the heater is in a closet or other small space, Gordon says. The devices are about 2 feet by 2 feet wide by 1 foot high and require, with ducts, a space of 4 by 4 wide by 8 feet high.

John Darling is a freelance writer living in Ashland. E-mail him at jdarling@jeffnet.org.

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