Another reader question - this time about air cleaners:
Subject: Air Cleaner
Message: Can an Air Cleaner be installed on an existing furnace or would it require a new furnace also?
Great question, Richard. Air cleaners are one of those things that every home could benefit from, but very few actually have. In fact, Indoor Air Quality (IAQ) in general is one of those things that is a relative unknown to most folks. First, let me answer your question directly and then I'll go into a little more detail.
Yes, an air cleaner can be installed on any furnace if space allows. The only restriction is that air cleaners are larger than just a standard 1 inch filter that the majority of folks have. As such, there needs to be enough space to move the return air duct (the one that comes back to the furnace where the current filter will be located) over between 7 and 12 inches, depending on the air cleaner.
As you can see below, air cleaners are wider because they have much more filtering material than a standard filter which allows them to be both better filters and last much longer than a standard filter without becoming clogged to the point of restricting airflow. That additional filter material allows air cleaners to offer much better performance, up to MERV 16, without quickly becoming the equivalent of a brick wall for air to try to get through.
Clogged up filters are a very common cause of air conditioning problems as the airflow can get so low that the inside coil begins to freeze over to the point it becomes a block of ice. Many people that want to improve their indoor air quality will go and buy the expensive filters from the home center - you know, the ones that offer much higher filtration than a standard 1" filter. The problem with those filters is that while they have great filtering material (similar to what you'll find in an air cleaner) they just don't have that much of it in such a small space. As a result, those filters become clogged up very quickly (after all, good filters catch a lot of stuff) and make your equipment work that much harder. The reality is that if you want good air filtration, you need to get a proper air cleaner.
The good news is that while the installation of an air cleaner certainly costs more than buying filters every month, the annual cost of your filter media isn't going to cost more - that's because you only need to change the media in an air cleaner every 6 months to a year, depending on how much "stuff" your house generates. As an added benefit, you don't need to remember to check and change your air filter every month, you can have it checked and changed when you get preventative maintenance done on your furnace and air conditioner twice a year.
Now to the question of whether or not a new furnace makes sense or is necessary with your new air cleaner. There is a cost benefit to installing an air cleaner with a new furnace (or visa versa), as much of the labor to install an air cleaner overlaps with installing the new equipment. In addition, new furnaces offer features like Variable Speed motors that make a great pairing with an air cleaner, allowing constant air filtration with low noise and low cost. In fact, we think they make such a great pair, we install an Aprilaire 2210 air cleaner with every variable speed furnace (if space allows).
That being said, if your current furnace has a number of years of life left but you would like an air cleaner I would say not to wait to enjoy the benefits of cleaner air. We can also install retrofit variable speed motors that allow for many of the same benefits of a True variable speed furnace without having to replace your equipment.
Good indoor air filtration is one of the most important components of IAQ and the one that everyone can use and benefit from. Other components of great IAQ include Humidification control, ventilation, and IAQ capable Thermostats. We can help control not only the cleanliness of the air, but also the temperature, humidity, and "freshness" (another way to say oxygen and CO2 content).
In order to determine what IAQ additons your family could benefit from, we offer an in-home IAQ test called the Air Advice. This device will sit in your home for a few days and constantly sample the air. It will upload its results and generate a report. You can see an example of one of the graphs from the report below, and if you click on the image, you can see a complete sample report. The report measures particulates, VOCs, Carbon Dioxide, Carbon Monoxide, Temperature, and Relative Humidity - all the important values to know to help you make an informed IAQ purchase decision.
I hope that helps answer your question, Richard, or anyone else that might have been wondering the same thing.