According to the EPA, indoor air quality inside a home is typically 5 times worse than outdoor air quality. New technologies have been developed for indoor air exchangers (sometimes called heat recovery ventilators or energy recovery ventilators), which can give you all the benefits of having open windows, but without losing all of the energy.
We’ve all heard about the problems of air pollution in the environment, but most people are shocked to find out that the air quality in their own homes is actually a much greater problem. There are a number of reasons why the air quality in your home is so much worse than outside air:
VOC (volatile organic chemicals) being released from carpets and furniture
Fumes from household cleaners and paints
Mold from damp bathrooms and basements
Naturally occurring radon gas which seeps up through the foundation floors
Fumes from cooking and smoking
To improve the quality of air in your home, you can open your windows. But of course, in the wintertime you will not want to do this. And in the summertime, you will not want to open your windows when you are running your air conditioner. In these cases, an indoor air exchanger can be so helpful. By bringing in fresh outdoor air while capturing up to 80% of the potential heat loss, these units can significantly improve your indoor air quality in an energy efficient manner. And models which are energy recovery ventilators can actually transfer the humidity between the air streams, keeping the humidity in your house when you need it in the winter, and keeping humidity out in the summertime when you don’t want it.
You can see examples of various models of indoor air exchangers online on Amazon.com.
The prices for the units can range from about $350 to $1,400, depending on the style, capacity, features, etc. The costs of the installation are additional. Electricity costs will vary according to the size of the unit you get. For some models, the energy use can be as low as about 60 watts (about the same as an average light bulb), but of course, you can be saving 900 watts of heat that would have been lost through an open window.
Some models of air exchangers can be mounted in a window or wall opening, much like a room air conditioner is installed. These are designed to handle the ventilation for an individual room, such as a kitchen, living room, work studio, etc. Larger units are designed for the whole house, and provide fresh air to all the rooms of your home. These larger units are easier to install if you have central heating or air conditioning duct work to which the units can be connected.
Your choice of air exchanger will depend on factors such as:
The volume of air exchange you need for your home
The configuration of your home’s ductwork
The humidity of the region of the country where you live
The tightness of your home's construction
HOW THEY WORK
The air ducts for an indoor air exchanger are intertwined with the air duct for the outflow air in the mixing chamber. As a result, the air flows do not mix, but the heat (or cooling in the summer) from the two air flows are exchanged. As a result, fresh air from the outside can come in without losing all of the heat (or cooling) from the inside air, thereby saving up to 80% of the energy.
The key elements of a typical air exchanger include:
From one port, fresh air is drawn from the outside, and from the other port, indoor air is cpnducted and expelled out.
The exchanger is a chamber where the separate air channels mix while separated from each other by highly conductive metal, which allows efficient heat transfer between the two air streams.
A material made of foam, metal, etc. which removes dust and dirt particles from the outside air intake.
A flat blade inside the air exchanger, which controls the amount of airflow.
Channels in your house that the air flows through.
A reservoir where water condensation is collected.
If the air exchanger is located in a basement below grade, then it will need a pump to eject the water condensate.
WHAT CAN TYPICALLY GO WRONG
Most of the problems with an air exchanger can be related to humidity. If you do not have the right size or type of unit for your particular home and weather environment, you can find problems such as:
The air exchanger will not turn on often enough, because it is limited by the humidity of the outside air
The unit is undersized for the volume of air in your home
Poor unit efficiency and motor failure, which can be a result of not performing the proper routine maintenance
Routine maintenance for an air exchanger will, of course, depend on the specific model that you have. But typical maintenance tasks for an air exchanger will include washing or replacing the filters on a regular basis, cleaning the exchanger chamber, and ensuring that the vents are clear and operating properly.