I need ideas for new filters for a new furnace


Old 01-05-20, 04:10 PM
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I need ideas for new filters for a new furnace

The old days are gone. My old furnace used old, simple, cheap filters.

But now I've got a new Trane S9X2 furnace. It calls for “high velocity” filters without defining that term or offering specific filter suggestions.

From searching around, from what I gather, I should get a pleated filter to increase the amount of filter “space” and increase the volume. What I also want is a permanent, washable filter, and from what I understand, I should get an Electrostatic Filter.

Using these criteria, there are still lots available to choose from with prices and attributes all over the place. So I have two questions:

1. Is my understanding of my filter needs correct?
2. Any particular things to look for or avoid in my selection?

I'd rather not spend $100 for a filter only to find that it's not the best for my furnace, or that I paid way too much.

Any ideas, thoughts suggestions will be appreciated.
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Old 01-05-20, 05:14 PM
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These high priced big 4" and above filters are a scam. Even 1" high end filters are a scam.

Think about how a typical forced hot air furnace operates. Your taking warmed air from the house and re-circulating it past a heat exchanger to increase it's heat temp, then blowing that same air back into the home.

Now what do you think the filter does? If you think it's filtering the air you breath, then think again! The filter is there to protect and keep the mechanical parts of the furnace "relatively" free from large dust particles such as cat and dog hair. The filter is placed just in front of the blower motor and belts and fan.

You can't expect that tiny little box in a basement to filter out all the crap floating around a big old house 1 and 2 stories high that is dragging in air from the outside from all kinds of cracks and openings. And the fact that the air is flowing thru non-air tight duct work, actually draws in contaminates that never see the filter media.

It can't be done, I don't care what the so called experts say. Think about how a real air purifier works, like in a hospital or a non-contaminated environment. Those places are sealed and it usually takes a dedicated machine to filter out a single room.

I will grant you that if you have a heavy dust problem or sever allergies than the better filters will tend to reduce the contaminates to a small degree. But that is all it might do.

Cheap furnace filters changed monthly or once every two months is better than any 4" or high priced piece of media. Remember, the filter is there mainly to protect the furnace workings, as opposed to the air you breath.

Ever notice that at the very first use of the furnace at the beginning of the heating season, there is a funny smell. That's all the sediment the air filter does not catch. You just get use to it after the first run.

Old 01-05-20, 05:29 PM
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I understand and agree completely. The manual for the furnace points out the importance of changing the filter every month to protect the furnace. It doesn't say anything about cleaning the air for the house. The filters I need are 1" thick -- I think it is 20x25".

Since the manual says get a high velocity filter, I assumed I should get a pleated one, but maybe not. You tell me.

I want a permanent, washable one, just to keep down the trash and eventually save money.

I really don't care about pollen, dust, etc. so I guess an electrostatic one is irrelevant -- am I right?
Old 01-05-20, 05:33 PM
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Pros And Cons Of Washable Furnace Filters

  • You don’t have to buy replacement filters.
  • Washable furnace filters are environmentally friendly.
  • You’re in charge of how often and when they are cleaned.
  • These electrostatic furnace filters are reasonably priced if you look at their useful life.
  • Most washable air filters come with a Lifetime Warranty.
  • These are readily available online in custom and standard sizes.
  • Electrostatic air filters are much more effective than standard disposable filters.
  • You will have to pay more at the outset.
  • You’ll order them online and have to wait for them to arrive.
  • They’re not HEPA filters or electronic air cleaners, and don’t work in the same fashion.
  • You’ll have to take the time (up to 15 minutes) to properly wash them in lieu of swapping out disposable air filters.
  • Washable electrostatic air filters can be constructed differently with a variety of filter media, and may not allow for as much free air flow as standard disposable filters do which may cause your furnace to work harder.
For what it's worth, I'll stick with the cheapies that you change every month or so.

edit...This to...
Are washable furnace filters good?

Even bacteria, viruses and smoke are not effectively filtered out. Disposable air filters are more effective in capturing small particles (dust, allergens, pet dander, smoke, bacteria, and viruses) and MERV ratings go as high as 16. Washable air filters require you maintain them monthly.
Old 01-05-20, 05:36 PM
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High velocity equates to maximum square inches which equates to pleated, as you found in your research. Concern yourself with matching resistance to your system. Don't go beyond MERV 8, hopefully less.
Old 01-05-20, 10:39 PM
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In addition, just think how little time the furnace is even running during a 24 hour period, not much air flow even going through the filter.

If you wanted even min performance you would have the blower running 24-7!
Old 01-06-20, 05:59 AM
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Many furnaces which spec "high velocity" filters originally came with what is often refered to as hog hair filters. These can usually be washed 2-3 times before they get flimsy & need to be replaced.
Old 01-06-20, 08:24 AM
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Distilling all of this very helpful information, I will look at pleated, washable, electrostatic filters with a MERV less than 8.

I suspect I'll be back with more questions.

Old 01-06-20, 11:30 AM
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Here's three that look promising. Each is not exactly what I want, but close:

#1 – BFO/BUYFILTERSONLINE AIR Filter Pleated Foam Permanent Washable Beats ELECTROSTATIC Lasts Forever Aluminum NOT Rusting Galvanized +Free Super Microfiber DUSTING Cloth (20X25X1)

***Pleated, Non-electrostatic, high air flow, MERV not rated, $45

#2 – 20x25x1 CARTER MERV 8 Lifetime HVAC & Furnace Air Filter Washable Electrostatic High Dust Holding Capacity Never buy another filter

***Not pleated, air flow unrated, MERV 8, $55

#3 – K&N Home Reusable Air AC Furnace Filter, 20x25x1

*** Pleated, washable, Non-electrostatic, high air flow, MERV 11, $55

I'm leaning toward #1. It seems to have about everything I want. It is not electrostatic and has no MERV rating, but otherwise looks good.

Any opinions?

Last edited by xkaes; 01-06-20 at 11:46 AM.
Old 01-06-20, 12:34 PM
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Id go with a 4 inch media filter. 2nd choice would be a 2 inch merv 8 pleated. No way would I go with a electrostatic filter. Way to hard on the equipment.
Old 01-06-20, 01:38 PM
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I've decided to avoid the electrostatic models, but I can only use 1" filters -- or at least I assume that is all I can use because that is the height of the slot in the furnace. Tell me if I'm wrong.

The three filters I listed above are all 1" filters.

Last edited by xkaes; 01-06-20 at 01:58 PM.
Old 01-06-20, 06:20 PM
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Just my opinion, but I like the 3M Filtrete red pleated 1" filters. You will always get a certain amount of dust in the airstream, but I have found the Filtrete filters keep the dust down to a very fine dust. I used the cheap 3/$1 fibreglas filters for years, but they do seem to allow a lot more coarse dust to settle on flat surfaces. In my mind that means I am breathing more coarse dust. I haven't found the Filtrete filters restricting the airflow required for my furnace. I change them every 3 months so 4 filters per year.

25 years ago I recommended these filters to a friend, he and his wife were both heavy smokers. He tried them and they both loved them, but changed them monthly due to the smoke they created. Again, just my opinion, but I think they are the next best thing to electronic air filters.

And one more time, I like electronic whole house air cleaners the best.
Old 01-07-20, 08:00 AM
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I actually use 3M Filtrete filters in my darkroom, where it's very important to keep dust down. The Filtrete filter is used to filter the air that is forced INTO the darkroom -- the air that goes OUT removes the chemical fumes -- but the air going IN has to be clean.

I can easily see the darkroom filter and can determine when it needs to be changed -- very infrequently.

But my furnace requires a high velocity filter which mean more frequent changing, so I also wanted a washable filter -- to cut down on waste, and eventually cost. So the Filtrete are not an option because they are not washable & permanent.
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