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Finally! A subject I can contribute to!
A high quality 2″ thick pleated filter will work better then most low-end electro static filter systems, they are cheap as dirt, and their efficiency can go as high as HEPA (99.97% or so)
I have a 2″ pleated filter and a cheapo 1″ pleated pre-filter impregnated with carbon for odor control. The pre-filter traps larger particles and costs even less than my 2″ I’ll change filters 2 or 3 times over the winter, less during summer. Air quality at my house is much, much better then with my systems stock filter.
Motor failures happen if you don’t replace your filters, better filters trap more particles and need to be changed more often. Also, the pleated filters provide more surface area, they perform better and last longer than non pleated filters.
To get around the problem of air by-passing the filter, have your HVAC or sheetmetal contractor fabricate a filter rack for the return duct with a screw on cover. The inside of the rack is lined with foam and compresses when I slide in a filter and close the door.
Good Luck,
Mike Farrell
farrelltech@netscape.net
Replies
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Just a few words about electrostatic air cleaners, A high voltage transformer is used to send an electrical charge through some very fine bare wires. This creates a situation in which the wires actually glow (corona effect). And that is the rub, This causes oxygen to form OZONE. This happens in office copiers (electrostatic copiers) as well. Ozone is not a friendly gas at ground level. I personally would not use this type in my home. If you do insist on getting one make SURE that it has a charcoal filter canister to absorb the pollutants that are caused by the process itself, And be sure to service it regularlly. Ozone is a bluish irritating gas with a pungent odor. It is a pollutant. GB
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Yeah, I wanted to add earlier that the "zapping" of the elctrostaic filter sounds more like a failure than correct operation. The unit as I understand it acts like a capcitor to set up a field, charging particles that pass through it so they can be pulled out of the airstream. A zap means enough crud has gathered to allow arcing, bad for the unit and a definite source of ozone, a highly irritating pollutant (the stuff that makes your eyes and lungs burn on a polluted day).
I guess I'm very much an open-window person. I know that's not possible for people with severe allergies -- at least when the pollen counts are high -- but in general I feel it is the single best step towards clearing the air. We don't live in the country, but we're not near any copper smelters either.
*I think that some of us are talking apples and oranges. Electro"static" filters have no electrical current involved, the filter fabric's inherent electrostatic charge draws particlates onto fiber surfaces, just like a magnet draws iron fillings. The electrostatic system that I'm speaking of is a three stage deal. The first,is an allergy prefilter, much like an ordinary furnace filter, only it's a bit thicker. The second is the accumulator chamber, followed by an after filter. I don't see any room for mechanical failure with this, that's why I'm leaning this way. The electronic cleaner was in the house when we bought it, it was the home inspector who politely "suggested" to the previous owners that they should maybe have cleaned the cells periodically! The damage to them was done by this point. Yes,...houses should come with manuals, but then, the majority of people wouldn't read them anyway!Beatrix
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Beatrix, If you are going to use an electrostatic air cleaner in your home after knowing that it actually creates an air pollutant called ozone, then be VERY careful to find out how to service that innermost filter. The one with the charcoal imbedded within it (the after filter). Ozone is an irritant and it gets real stinky. Also Beatrix, could you give the rest of us the benefit of your information on exactly how the so called "inherent electrostatic charge" of the filter fabric works. You say that "I don't see any chance for mechanical failure with this" ... Within the unit there needs to be a charging unit, a HIGH VOLTAGE transformer and many thin wires that carry the charge and like to break. Remember Murphy's law. The accumulator gets dirty and needs to be put in the dishwasher or cleaned in some way. For this to work well requires a great deal of servicing. It is NOT a good way to go. Avoid it if you can. I cannot see the wisdom of creating a pollutant and circulating it throughout the house. All in the name of removing pollutants from the air.
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Actually what she wants is passive -- no electricity -- I think these are called "media filters"? and are expensive.
*Billy Bear,I don't think that you and I are speaking of the same system. There is no charcoal filter involved here, nor a transformer and wires. Am I wrong in saying that you are talking about an electronic cleaner? That's what we are looking to replace, and for the reasons that you mention. Adding pollutants to my home is the last thing I want to do! I posted my question in order to make the best, informed decision. Many people swear by the electronic systems, but I've questioned it for a while now.If I understand correctly, the filters in the electrostatic system work by simply attracting and holding the particles, in the same way that clothes stick when you have static cling or when you can stick balloons on the wall after rubbing them on your hair. There is no electrical current involved.Beatrix
*BSounds to me like you want the pleated filter system detailed by MFarrell above, which I also mentioned in my 2nd post, it's certainly the way I'm gonna go.-pm
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I had our electronic air cleaner serviced today; the technician suggested that I buy a permanent high efficiency electrostatic air filter rather than replace the electronic cells. The cost would be about the same either way. I had always been under the impression that the electronic cleaners were the most efficient. Any advice??
Thanks,
Beatrix
*BeaWhen I switched from burning wood about 3 years ago, because, among other things, my 5 year old son was developing asthma, I had an electrostatic installed with my new forced air furnace. I had heard good things about them, but my furnace guy thought I was wasting my money. . . I've come to think he was right. We have no smokers here, and I clean the thing regularly during heating season, and while it is always dirty, it just doesn't seem to do much of a job. . . our house seems to be just as dusty as it was when we had fly ash all over the place, and it seldom snaps to indicate that it's doing anything. . . my conclusion: an expensive ($450.00 Cdn) mistake. If I had to do it over I would buy one of those new portable muli-stage filters that clean down to 3 microns, that the tool suppliers sell. . . about the same price for a large capacity one.-pm
*I mentioned in a separate thread that I've heard nothing flattering about the expensive electrostatic filters -- high failure rate, lean results. "Media filters" are the expensive inert alternative you may be thinking of. Stand-alone HEPA may be most efficient choice.Re Fred's comments, the furnace people do want the filter to protect the fan and heat exchanger from accumulating stuff. But his point sounds good. when we moved in the filter had an inch of fur on it and the motor was NOT happy.
*Bea: If I understand correctly an electronic air filter causes foreign matter in an air stream to become charged (either pos. or neg. I'm not sure which) as it enters the filter area. As the air moves downstream in the filter it passes a collector plate that is charged opposite of the particles. This causes the charged particles to adhere to the collector plate where they stay until the filter is cleaned & re-installed. The electrostatic filter is a filter medium that is very dense (closely packed) and filters the air. As stated in some of the other posts they are not near as good as some would have us think. They can & often do cause more harm in a system than good. Not enough air is able to pass thru them.This lack of air flow causes excess heat to build up in the furnace in heat mode & can cause the AC coil to freeze when attempting to air condition the building. We have had an electronic air filter for over 20 yrs. I clean it 3 or 4 times a year. ( 15 to 20 min.max) I would not be in a house without one. We recently installed a new furnace & the electronic was re-installed in the new system. I had proposals from 3 heating subs that I work with and all three said use old the electronic filter. The only thing a new one will do is raise the cost of the new system. WE spent our money on a second filter. We added an air purifier. This is the same type of filter used in many medical buildings. This filter actually kills germs, ect. We are using only the two filters and have the best air quality I have ever lived in.Hopes this helps a little. Ron.sorry about the length of this.
*I understand Fred's point about "high performance" filters putting too much of a load of furnace blowers, and he is correct that a 1" thick filter that is so efficient so as to filter out bacteria is potentially bad for you're your HVAC system. On the other hand, 4" - 6" thick furnace filters are manufactured that are supposedly designed to not restrict air flow enough so as to place excessive loads on the furnace blower. These filters are neither thin or cheap! An example of one such filter can be seen at http://www.resprod.com/sg.html. They may be worth consideration for new system installs. Does anyone know anything good, bad or indifferent about these filters?
*Well. . . I stand/sit corrected. What I have is exactly what Ron describes above as an Electronic Air Filter (always thought thei "charging of particles" process was called electrostatic) . . . but I'm still not happy with it's performance. All it seems to have done is take the place of the 'passsive' fibre filters at several hundred times the cost, and maintenace!!!-pm
*Well, I'm leaning towards the electrostatic cleaner, but haven't fully decided yet. Less maintenance, no noise. I found the electronic cells a pain to clean. Having allergies in the house,I feel that we need "something". I've only heard of allergy specialists recommending electronic air cleaners though.The unit that I was shown is about 2" thick, it supposedly does not restrict air flow (if kept clean!),the particulates drop down into a accumulation chamber. I was quoted $200, sounds like you guys are speaking of more expensive units??Patrick, this electronic cleaner would zap constantly at times, either I have a much dustier house than you or it was killing rodents in the ducts!! Fred, pardon my ignorance, but what do you mean by "balancing ducts"?Beatrix
*Finally! A subject I can contribute to!A high quality 2" thick pleated filter will work better then most low-end electro static filter systems, they are cheap as dirt, and their efficiency can go as high as HEPA (99.97% or so)I have a 2" pleated filter and a cheapo 1" pleated pre-filter impregnated with carbon for odor control. The pre-filter traps larger particles and costs even less than my 2" I'll change filters 2 or 3 times over the winter, less during summer. Air quality at my house is much, much better then with my systems stock filter.Motor failures happen if you don't replace your filters, better filters trap more particles and need to be changed more often. Also, the pleated filters provide more surface area, they perform better and last longer than non pleated filters.To get around the problem of air by-passing the filter, have your HVAC or sheetmetal contractor fabricate a filter rack for the return duct with a screw on cover. The inside of the rack is lined with foam and compresses when I slide in a filter and close the door.Good Luck,Mike Farrellfarrelltech@netscape.net