Here are a few options to get fresh air in airtight homes

Q. I have an energy efficient house that is fairly airtight. I installed new windows and doors. Now the indoor air does not seem as fresh as it used to and odors linger. How can I get more fresh air indoors efficiently?

A. Although installing new windows and doors is good for energy efficiency and reducing your utility bills year-round, it can lead to some indoor air quality issues from a lack of fresh air infiltration. There are efficient ways to solve these problems and you are certainly better off with the new windows and doors.

The same problem sometimes happens when a new furnace, which uses sealed combustion, is installed. The old furnace drew its combustion air from inside the house. This caused outdoor air to be drawn in through cracks and gaps in the exterior. This did waste energy, but made the indoor air fresher. Excessive wintertime window condensation is often the first thing noticed when a house is made more airtight.

The most energy efficient method to solve your indoor air quality problems is to install a fresh air heat recovery ventilator system. These systems also provide the best comfort because they can be set to automatically sense when and how much fresh air is needed for good indoor air quality.

The basic design is simple. Incoming fresh air and outgoing stale air pass each other in a heat exchanger. The two air flow paths are kept separate, but they transfer heat and/or moisture between them as they pass each other.

During the winter, the outgoing stale indoor air is warm and the incoming fresh air is cold. When they pass each other, the cold outdoor air is warmed by the outgoing indoor air. This saves the majority of the heat from the stale air. During the summer, the outgoing cool stale air precools the incoming warm fresh air to recover the energy used for air-conditioning.

If you live in an area where high or low humidity is an issue, select a heat recovery ventilation system that also transfers the moisture in the air as well as the heat. These systems are referred to as ERVs. These are particularly effective during summer when you do not want to add humid air to your home.

Most systems are designed with their own ducting system. They often draw indoor air from the kitchen and bathrooms. This is where most moisture and odors are created. The fresh outdoor air vents can be located in other commonly used rooms.

A less expensive, but also less efficient, system uses a damper to allow outdoor air into the furnace duct system. There are automatic controls available to improve efficiency somewhat. Another option is to just open two windows for a couple of minutes twice a day. Heat content of the lost air is not tremendous.

The following companies offer heat recovery ventilators: Aprilaire, (800) 334-6011, aprilaire.com; Broan, (800) 558-1711, broan.com; Fantech, (800) 747-1762, fantech.net; Honeywell, (800) 328-5111, yourhome.honeywell.com; and Renewaire, (800) 627-4499, renewaire.com.

Q. I installed a new range hood two years ago and it works fine. Sometimes when there is a strong wind outdoors, I can feel a draft coming from it. Did I install it wrong and how can I stop the draft?

A. The range hood should have a flapper in the duct stub which attaches to the duct. The flapper may be jammed in the open position. You may have to remove the range hood from the cabinet to check it.

The flappers do not seal perfectly. If it is working properly, check the vent outlet on the roof. There may be some unique situation, perhaps a location near a chimney, which directs the wind into the vent. Try a different vent cap.

• Write to James Dulley at 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit dulley.com.