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
call heat recovery ventilators or energy recover
ventilators), which can give you all the benefits
of having open windows, but without losing all of the
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
- 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.
- pet dander.
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.
This is where 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: indoor
As you will see, the prices for the units can range from
about $350 to $1,400, depending on the style, capacity,
features, etc. And then you will need to add the
costs for the installation. Further, in addition
to the initial cost of installing the unit there are also
the operating costs for electricity and routine maintenance.
Electricity costs will vary according to the size of the
unit you get and your local electric rates. 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 ductwork to which the units can be
Your choice of air exchanger will depend on factors such
- 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
- how tight the construction is of your home.
As shown in the diagram here, the way an indoor air exchanger
works is that the air ducts for the intake air is 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 ducted and expelled
Exchanger: 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.
Filter: A material made of foam, metal, etc.
which removes dust and dirt particles from the outside
Damper: A flat blade inside the air exchanger,
which controls the amount of air flow.
Ductwork: Channels in your house where the
air flows through.
Drain pan: A reservoir here water condensation
Condensate pump: If the air exchanger is
located in a basement below grade, then it will need a
pump to eject the water condensate.
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.
unit is under-sized for the volume of air in your home.
Other typical problems are poor unit efficiency and motor
failure, which can be a result of not doing the proper
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, ensuring that the vents are clear
and operating properly.
Indoor air exchangers are a great innovation for improving
the quality of air in your home for you and your family,
on an energy efficient basis. However, you will want to
carefully choose which model is appropriate for your particular
home situation, and if you already gave one, you will
want to do the proper routine maintenance for it.