Heat recovery ventilators

Stagnant indoor air can quickly be contaminated with pollutants like dust, mold, pollen and even carbon monoxide. A heat or energy recovery ventilator can remedy this potentially unhealthy situation - and help lower your utility bills.

In this video: An expert in indoor air quality discusses the importance of proper ventilation and ways to circulate the air in your home.

Why it's important

As you tighten up your home with insulation, weatherizing and even duct sealing, fresh air becomes a big concern - sealing up all those air leaks also prevents outside air from entering your home.

Indoor air quality experts say the air inside your home should be "exchanged" with outside air a minimum of eight times in a 24-hour period. But the average home has only five - or fewer - air exchanges in a day. In a poorly-ventilated house, the air inside may be more health-threatening than living in a smog-infested urban area!

How it works

Unlike other mechanical ventilation systems like your bathroom vent fan or kitchen range hood, an energy recovery ventilator not only gets rid of air inside your home, it replaces it with fresh outdoor air.

As the indoor air is sent outside, a heat exchanger inside the ventilator extracts the warmth and uses it to pre-heat the incoming fresh air before it reaches your furnace. During the summer, the heat exchanger works in reverse to expel heat from the incoming air as it heads toward your air conditioner.

An energy recovery ventilator, which also regulates humidity levels, can be connected to most forced-air heating systems. Similar systems called heat recovery ventilators with no humidity control are also available.

The benefits

One of the biggest selling points of a high-efficiency ventilation system is energy savings. Up to 85 percent of the heat from the exhaust air can be recovered and reused, significantly reducing the demand on your furnace. And like a geothermal heat pump, the system works in reverse during the summer, eliminating unwanted heat and humidity.

According to manufacturers, an energy recovery ventilator uses only 100-200 watts of electricity per hour - compared to the 2,000 to 4,000 watts you can save by building an energy-tight home.

Another important advantage - but one that might go unnoticed - is a healthy balance of air exchanges. The system, which can be combined with a high-efficiency air cleaner, is very effective at expelling indoor air pollutants.

And because it draws in fresh air at the same time, it won't create a vacuum effect from uneven air pressure - a situation which can draw in radon gas from the soil, create moisture problems and cause problems with gas appliances.

Other benefits include:

• Quiet operation from a single unit contained in an isolated area
• Humidity control (with an energy recovery system)
• Low maintenance and long lifespan

The cost

The cost for installing an energy recovery ventilation system in a typical Midwest home will range from $2,000 to $4,000, depending on the type of ductwork and heating system in your home.

Keep in mind that the energy savings you'll realize will help offset that investment. Your heating contractor can help you determine how much energy you'll save and how long it will take to pay back the initial cost.

While most ventilation systems are included during construction of new home, they can also be added existing homes. Contractors should perform a blower door test to analyze air flow through the home before making a recommendation.