Filters, what is enough, where do you stop?

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Old 01-09-04, 04:07 PM
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Filters, what is enough, where do you stop?

I am in the process of changing/modifying/listening to what the guys on this web site have to say. I really believe I am getting some great advise, so I plan on "going to the max"!
All of a sudden filters have become very important to my energy search.
But where is the cutoff, where do you start wasting money reaching for something that is not there (Hype)! It appears that the pleated filters are better than the others, but what do I know. I am speaking of "Furnace Filters" in case anyone is confused.
Bottom line, what is an excellent filter for the average homeowner who follows a replacement program without getting caught up in the "Hype"?
Changeling
 
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Old 01-09-04, 11:01 PM
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Forced air systems are closed systems

The amount of air that goes into your forced air system equals the amount of heated air that comes out. What this explicitly implies is that a filter that is dirty will prohibit the amount of air that goes to your furnace, hence it will prohibit the amount of heat that comes out. If it takes twice as long to circulate the air in the house through a dirty filter, it will cost you twice as much to heat the house.

So if I take two filters, both are rated to have 2000 cfm air flow, one cost $.50 and the other $30. What's the difference? Besides price. Well the $30. filter will catch more dirt than the fifty cents filter. Which means the $.50 filter will let some dirt through that the $30. filter would not. Though it is relatively little, over a prolong period of time, the dirt that the $.50 filter allows through will accumulate. This in turn will affect the performance of the furnace, from maintenance to replacement.

On the other hand the $30. filter is going to collect more dirt than the $.50 filter. The way they overcome changing these expensive filter so frequently is by pleating the filter which produces a much larger surface area for the air to flow through. Even though this may be true, you should change these expensive filter a lot more frequently than what the manufacturer states. Regardless of the increased surface area created by pleating, these filters will get dirty fast and that will affect air flow through the filter, more so than a $.50 filter and a lot faster. So the increased energy cost and the expense of the $30. over the same period with the $.50 filter example mentioned above could easily equal the cost of maintenance to replacement.

So hell if you do and hell if you don't. Well that is not exactly true. First we must understand what is the primary purpose of a furnace filter. And that is to protect the furnace from getting dirty. So it is not really there to clean the air in the house. Yet it is the air in the house that makes the filter get dirty. To take this a step further it is actually cooking and washing that are the major contributors to that filter getting dirty so fast, with all other things being equal. So use an exhaust fan when you're cooking and showering and your filter won't get so dirty fast. Use a decent air filter, like a $3. one and check it frequently, like once a month. Change it if you think it is dirty, you'll get your money back on your energy savings.

I got some questions, "Do you think leaky return ducts make your filter get dirty faster?" Will it affect the maintenance to replacement of your furnace? Will it make your energy costs more? Answers, YES! YES! YES!
 
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Old 01-10-04, 12:02 AM
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I don't care for the pleated filters. They REALLY overwork a blower motor in a hurry. If you want better filtering than a standard filter get an electronic air cleaner.
 
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Old 01-10-04, 12:44 PM
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Resercon, your ability to answer questions so that I can understand and comprehend the common sense is AWESOME! It shall be done your way.
Changeling
 
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Old 02-12-04, 10:14 AM
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We started out using the fancy pleated filters on our new heat pump. They're supposed to filter out all of this dust right? That *sounds* like a really good idea. Until I noticed that the blower was staying on for an inordinately long period of time. Went to the little cheapie "blue" filters, change them more often. Problem solved.
 
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Old 02-14-04, 11:36 PM
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Cool

When we replaced our central HVAC system (4-ton Carrier heatpump) in '98, they recommended 1/2" thick layered plastic mesh filters in a rigid plastic frame that I backwash with a waterhose monthly. (First of every month without fail.) They cost $112.
The over-and-under common-duct wall returns are at ceiling level upstairs and at floor level down. Each is about 32" high by 18" wide, I think.
They seem to collect a lot of dust, dog hair, etc. each month, especially the one downstairs at floor level.
I use a water hose with sprayer off of the water heater drain spigot and the downstairs bathtub in inclement and freezing weather, and a regular water hose outside in good weather.
I install temporary inexpensive plastic mesh (no frame) filters in their place during the day they're drying out.
Resercon and webrebel, what do you think of those kind? Ever heard of them?
(I probably got ripped off, as usual. LOL)
Mike
 
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Old 02-15-04, 08:03 AM
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Are you talking about the green jobs? If so $112 does sound a little steep....

But these must be different, got a brand name?
 
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Old 02-16-04, 08:18 AM
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These are black plastic framed, off white plastic mesh 18X36" HVAC return filters - A2000 made by Filtration Manufacturing, Inc. of Andalusia, AL, to be backwashed monthly.
I use the frameless green mesh filters when I have these out to backwash and dry for the day.They seem to trap a lot of dust, etc.
Mike
 
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Old 02-16-04, 08:46 AM
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The expense of the filters in my opinion is high and there is another reason why I do not recommend washable filters. Since most furnace blowers move about 2,000 cubic feet of air a minute (cfm), they are usually capable of moving all the air in the house in less than 6 minutes. This is done several times an hour. The problem I have with the washable filters are the germs in the house are collected in the filter and merely washing them does not get rid of the germs and bacteria. Because of the amount of air movement through air filters on a Forced Air system, when you throw out a disposable filter, nearly 90% of the germs and bacteria in the house goes with it. I do not care what anyone says, there is no product on the market so reasonably priced that can accomplished that. Not even close to it.

Since you already have this washable filter, I do not recommend you dispose of it. Rather I recommend that you use it to try and get some of your money back. When it is no longer useful, do not purchase another. In the mean time, after you washed the filter, I strongly recommend you spray it with any common household disinfectant , like Lysol, before re-installing it.
 
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Old 05-07-04, 10:38 AM
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Personally I think installing a 4" thick pleated filter offers the best bang for the $$$
Just have your HVAC contractor have the filter slot made for a 4" filter instead of a 1", you don't need and expensive "air cleaner" (basically just a metal frame) just to hold the media filter.
Geniric 4" media filters are normally less than $10 each and last 6 months.
Easily the best bank/buck ratio IMHO.
If your house use a "filter grill" or has an "open" return under a furnace installed in a closet, it is normally easily to modify allowing a 4" filter to be installed.
 
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Old 05-08-04, 10:01 AM
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Wink

It just seems to me that ever time we have a AC coil that is full of dirt they have been useing a washable filter or an electric filter in the unit, most of the time. That wet AC coil is one of the best filters and if dirt can get to it ,it will stay on it. That is why I like a pleated low MERV filter. Put a light filter spray coat on it and put a new one in every 30 to 90 days when the units is running.

My .02 cents

ED
 
 

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