Gas and Oil Home Heating Furnaces - Air Filters

As a new home owner, I have a bit of a "stupid" question. I have heard that the higher priced air filters are really not the "way to go" because they end up blocking air flow. I have heard that they are so thick (in order to provide better cleaning) that they really have a tendency to harm the air unit's motor. Is this true? Should I stay away from the "better" cleaners?
Thanks,
Mark

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Thanks for the info.... Helps a great deal.

Originally posted by mwazz
Thanks for the info.... Helps a great deal. A trick we did years back with filterswhen you had a 2" filter we put in 2 1" then the next time you changed the you sild the one that was it there to the intake side out and put the new one next to the furnace it works good if you have the room. Now all is 1" So now with them if you want there is a filter coat and on a new filter you just put a very light spray on the intake side and slip it in.Also you can go with a good electric filter on your unit. They are very good if if if.The not working calls we get are that people dont clean them as much as you have to to make them work.;) ED

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i went with what we call here in georgia, an "air bear" made by trion, 5 inch pleat available in several sizes. i considered the spaceguard by aprilaire, which is an outstanding filter, but the efficiency difference was minimal, and the air bear is easier to change, once a year. if you go with a 1 inch filter, i do not reccommend the 3M filtrete, the high efficiency one that costs about $15. although this is a great filter, the restriction it puts on the airflow is in my opinion too much. i have seen this many times, and recommend oversizing the filter should it be used.

I agree with hvac4u. The pleated filters are nice, bUT, you have to increase the return air flow to compensate for the additional restriction they impose. My experience has been that the vast majority of homes have inadequate return air grills/ducting to start with.

Im with you there Bigjohn,The size of duct that i see down here is bad bad.On 3 ton units here most of the time you will see a 20" x 24" return grill and filter then the hole at the unit is about 12" x 12" for the RA to get back to the blower.In fact one home i was in had just a 12"x12" duct all the way back to the unit for the return. I was always told to work a job at about 80" to 60" per ton on the duct lay out ;)

There are many types of Air Cleaners/Filters on the market. Electronic Air Cleaners, UV Air Cleaners, whole-house HEPA air cleaners, Media Air Cleaners (1 and 5 inch.) It all can get very confusing so let's talk about each one.

Electronic Air Cleaners: Have been installed for many years but are showing a dramatic decline recently for numerous reasons. They have very impressive efficiency ratings; here is an example of a popular brand:
.35 microns=94%
.50 microns=95%
1.0 microns=98%

But get this, after a 72 hour period of operation, their efficiency will drop by 50%! To keep up on the big numbers, you need to thoroughly clean the plates and wires often. Read the small print on some manufacturers owner's manuals, you'll be amazed about how often they really need to be cleaned to keep a decent efficiency. Plus, have you seen the prices on these cleaners, geesh! With fewer and fewer electronic cleaners being sold each year, we can now see why.

UV light/germicidal air cleaners- This was an area that we (Skuttle) were seriously thinking of manufacturing...until we put all the answers from our research together.
Imagine yourself as a particle of bacteria. Walk outside during the day for 5 minutes, and then walk back inside. Basically you did the same thing that typical household bacteria just did...you survived UV light! When dust particles, bacteria etc, travel down the duct at speeds around 500 ft. per minute, they will not be exposed by the UV light long enough to be sterilized. Even counting on UV reflection within the duct by panels, will not do the job. Common bacteria needs to be exposed to UV light between 12-24 seconds in order to be sterilized.

Have you ever seen what happens to a filter after being exposed to UV light over time? It looks like cotton candy! The intensity of a common UV light will break down the filter and send it on its way through the furnace. Yikes! Some manufacturers make a special UV light filter, that's fine except if you look at the back of that filter you will see a poorly designed non-UV media and non-UV pre-filter too.

Let's say you have the UV light close to the A-coil. That's great if there is a UV stabilizer in the condensate pan. If you don't have one...these things can occur: plastic will degrade and crack which leads to water on the heat exchanger (think rust) which leads to holes in the heat exchanger which makes carbon monoxide leakage a possibility. Duct board is also not up to the challenge vs. UV light. Fiberglass within the construction of some kinds of non-UV stabilized duct board can also be damaged. UV light is great for a few things; getting a tan and for hospitals that need to completely sanitize an operating room. (FYI, they use multiple lights and clear out the room for at least 20 minutes to rid all the foreign bacteria)

Whole-House HEPA Filters- Excellent way to filter all the air in your entire home. Physically, they are rather large and take professional work to install (more than other filters) and unfortunately seem to be around 5 times more expensive than a good media filter.

Media Air Filters- There are numerous media air filters/cleaners on the market. Let's break them down into the 1 inch group and 5 inch group.

The one inch media filters can easily be bought from any retail store and in many sizes. 1 inch filters will give you exactly 1 inch of filtration, not nearly enough to help the entire house. Their dirt holding capacity is greatly limited and needs to be replaced often to insure decent filtration. Some of the newer "allergy" filters have high resistance which is good for blocking out bacteria stuff but not good at all for your furnace blower. One of the few things good about these 1 inch filters are that they are easy to put in and are very cheap..

5 inch filters have the least amount of maintenance, highest efficiency over time and best value. The pleated design makes for truly superior performance and the ease of installation is literally a snap and usually done only once every 6-12 months! There are varying designs with the 5 inch filter. Some filters are a box type that can be easily exchanged and others have an accordion type filter that is a pain to install and extract yet easy to store. You will also see different ratings, HEPA, Merv 8 etc."

Your air filter is more important than think. Can you put a price tag on clean air in your home? Take time and do some research and find the right air cleaner for your home. Call your local HVAC dealer and ask them to recommend for you a good media Air Cleaner. You, your family and body will aprreciate it.