OT: Which is better? Electrostatic or pleated air filters?

[Colin]

Which is better? Electrostatic or pleated air filters?

I have loved electrostatic air filters for my AC system for
years. The Wouse (was-spouse) and I had our house ducts cleaned. Then we
switched to an electrostatic filter. It costs more, but lasts forever, yet cleans
dust and allergens down to 10 microns. The ducts, air, furniture and carpets
seem so much cleaner. Been recommending such filters to friends ever since.

Yet, my AC stopped recently. The repairman, electrical
engineer with 18 years experience, said the culprit was the electrostatic
filter. Sure enough, the air handler and coils were finely coated with a thin layer
of moon dust. It had to be sanitized, which took three hours and cost as much
as a whole house duct cleaning ($250).

He said the cheap, pleated filters were better. Yet they
allow much larger particles through, so the ducts eventually need cleaning.

So which is better?

• Pay a
  larger up one-time front cost for electrostatic filters for cleaner home
  and air, and risk clogging your air handler and coils?
• Or, keep
  buying and replacing cheap pleated filters that don’t filters as well but
  won’t harm the air handler?

[wuzzzer]

We had a dead sparrow stuck in our furnace's air intake and when the furnace company came to take care of it I asked him the same question. The previous owners of our house also had an electrostatic filter but I took it out and replaced it with regular filter. He said, go to Home Depot, Menards, etc and buy the cheapest pleated filters you can find. They're usually blue and you can get a case of them for less than $10. He said the main thing is change them once a month and you'll be fine.

[oldtimer]

I had my whole system replaced about 4 years ago, ducts and all. I had been using the up to 3 month 3M rigid pleated filters, and the installer told me to keep it up. It was actually amazing how clean my 20 year old ducts were. I never had them cleaned out all that time either. The new ducts are a higher r factor. I change the filter at the end of each quarter. I guess based on my experience that I recommend the middle way of expensive but less frequently changed pleated, rigid filters.

[LarryC]

I had an electrostatic filter installed at least 15 years ago, and have never had a problem that I know of with moon dust piling up in the system. I remember the air smelling fresher for the first time in my 60-year-old house. I do wash the filters once every other month in the dishwasher as recommended.

The downsides for the first few months were an occasional sharp odor that suggested ozone but went away after a few weeks, and a white chalky residue on the furniture that also went away after a few weeks or months.

A friend of mine didn't have room for an electrostatic, so she had a high-MERV pleated filter installed on the recommendation of her dealer, I think MERV-11. She feels it works well. Dunno if cheap or more expensive, but that may be the way for you to go.

I don't think I'd go back to fiberglass filters.

[MrMcGoo]

Colin,

The place to ask this question is hvac-talk.com. The pros tend to recommend 5 inch deep pleated filter boxes. These boxes get it all above mthe micron level that you install, but they need to be changed mothly to quaterly, depending. The advantage is lower initial cost, less to go wrong and easire maintenance, but spare elements must be kept on hand.

I went with a low ozone eletronic filter. It has a pre-filter that I vacuum every three weeks along with the collectors. My first annual service showed no buildup on the blower wheel. We did not look at the evaporator coil, but the system was barely a year old. My system is a 3 ton heat pump which is to say that the air must move up to 1400 CFM to run right. The variable spped air handlers add rpm to get the needed cfm.

Bill

Bill

[oldtimer]

I get the highest rated, costs about 20 bucks a quarter. Not cheap but cuts out allergens and dust pretty good, plus peace of mind of starting fresh every 3 months.

[Invidiosulus]

What is this AC you speak of?

We just put box fans in our windows all summer.

[Groomlakearea51]

The "Minion" (david.reed21) is an A/C man with commercial and industrial A/C experience by trade. He advised pleated with monthly changes for home use because the ES filters don't catch negatively charged particles, and once they get dirty, they don't catch anything. He also said they can also burn out transformers, etc. Primary use is medical, homes with folks who have respiratory issues, but have regularly scheduled maintenance & cleaning. Pleated, according to him, generally will do the best, particularly if they are changed every month. They also catch most everything. The only "down side" with pleated is that if they are not changed every month, they will restrict airflow and electric bill goes up. For those folks with pets, they need to be checked every couple weeks and with long haired pets, may need replacing every 2-3 weeks.

[Colin]

Interesting

[Groomlakearea51]

Funny, I asked the same question not too long ago. I guess for the average homeowner, pleated will do very well if changed often. My ducts, handler coils, etc were inspected about 6 months ago when I had two additional 8" flexi-ducts run to the man cave. Minion remarked that the ducts and coil were very, very clean and the conversation got around to the "how often do you change filters". Apparently that is the key, and an annual coil "vacuuming" by a service tech. Here's what he told me to do (and save about ~$100 or more for a tech service visit).

• SAFETY FIRST: Turn the handler off... Usually a big breaker box somewhere within about 2 feet of the handler, or can be built on the front (Rheeem, Ruud, and Trane units).
• Remove the handler cover (usually 4-6 screws along panel edges)
• Use a spray bottle with a solution of dishwashing liquid and distilled water, and spray the coil
• Let it sit for about 4-5 minutes
• Use a vaccum cleaner with a brush attachment and carefully vaccum off the dirt. Be very careful not to bend the fins on the coil.
• Spray distilled water on the coil again to rinse any excess residue, etc. off.
• Clean out the drain pan (located underneath the coil) with mild detergent and vaccum out.
• There should be a PVC "t-fitting" on the drain line with a cap on the top of the T. Remove the cap.
• First, vacuum out the drain hole; recommended that it be done from outside the house.
• Pour about one capful of household bleach down the tube.... Then about a quart of water to flush it out.
• Replace the cap on the T. If you don't replace the cap, the unit will "suck" air through the open cap and flood the drain pan....
• Replace handler panel back on the handler.
• Set thermostat to "fan only". (IMPORTANT!!). DO NOT leave thermostat in "cool" position.... or residual water will turn into giant ice ball and can damage coil, compressor, fan, etc.
• Turn power on. Fan will run and dry the coil off completely. Let it run for about 30 minutes.
• After about 30 minutes, return thermostat to normal position.
• Replace filter

This can be done every six months, or at least once a year. A/C tech recommends in late spring to get ready for the summer. This service can cost anywhere from $75 (Okeechobee price) to well over $200 in urban (expensive....) areas.

Techs will often use a bleach solution to clean the coils, but Minion recommends not to do that inasmuch as if you don't get it off properly you will gas your family, pets, and guests....

[LarryC]

Is the filter's MERV rating important? I'd understood it was.

What about HEPA units? http://yourhome.honeywell.com/Consumer/Cultures/en-US/Products/Air+Cleaners/HEPA/Default.htm.

I've also heard of multiple-filter units.

http://www.lennox.com/products/indoor-air-quality-systems/MERV8/; http://www.furnacefiltercare.com/merv-ratings.php; http://www.furnacefiltercare.com/index.html; and http://www.furnacefiltercare.com/compare-furnace-filters.php. The last looks especially interesting.

[Groomlakearea51]

My financial guru, weapons chief, demolitions consultant, head A/C tech advisor, and workshop veneering asssistant (The Minion) is standing by....

Minion says: MERV.... Higher MERV, smaller the object has to be to pass. Good side - higher MERV = fewer allergens passing through. Bad side: Higher MERV's have to be changed more often; tend to restrict air flow; and are more expensive. Experiment with which MERV rating does the job, but does not bankrupt your filter fund..."

Minion says: HEPA.... Filters have a static "charge" and will attract either positive or negatively charged particles (dependent upon the brand, but they do not say which charge). Good side: They grab smaller pollutants which would otherwise pass. Down side: They can pass neutral particles, and when the filter gets dirty, they lose their effect. They can also be pricey.

Minion says: Multiple filter systems on any one unit is probably not cost effective because they will restrict air flow. The primary use of multiple filters was/is to attempt to ensure the coils stayed clean if the homeowner failed to change the filters on a regular basis. The problem arose that in the case of the lazy homeowner, both primary and eventually the second filter would get so dirty that airflow was so badly restricted that the AC unit ceased to work. Dirty filters = restricted airflow = damage to components. A/C companies love the multiple filter units!!!! More filters to sell during the annual service call; more damaged components to replace because a lazy homeowner never changed the filters, etc. A/C companies also charge about twice as much for filters as opposed to what one pays for the same filter at Walmart or Home depot.

Minion says: You can use a multiple filter effectively, if they are not "in-line", say with an air handler filter "box" that has two exposed sides. A second filter holder on the other wall will allow greatly increased return air flow, but at no increased restrictions.

Minion now says that I owe him for these words of wisdom......

[LarryC]

I guess I'm glad I have the Honeywell electrostatic (now that the ozone odor and white chalky stuff are long gone). I only have to do a couple of diswasher cycles, for the two core-gross filter pairs, every other month. I don't think there's a lot of airflow restriction.

[Colin]

Colin. It’s a mixed bag.

The limiting factor is the static pressure
capability of the blower. In most residential units this is very limited and it
means the higher efficiency filters plug up and kill the air movement. The electrostatic
eventually plug up but often give slightly higher efficiency for several months
before they start to restrict the air flow. New high efficiency pleated filters
can filter down to 3 micons at 60% plus eff. But they should be changed monthly
to keep the unit operating at peak eff.

Hope this helped

Yours,

Walter Golding

President,

Process Air System Sales, Inc.

[JL Sargent]

We use the cheapest filters but change them regularly. We have never had our ducts cleaned. Nobody had their ducts cleaned until somebody dreamed that service up a few years ago. Go figure. Central heating and air has been around for 40+ years yet only in the last 10 or so do we need duct cleaning.[^o)]

[Colin]

One other thing that I was late in
noticing.

It appears the service tech had to clean
the cooling coil.

The material that causes the dust to stick
to a cooling coil is a thin film exuded by mold growing on the coil fins. It
also acts as a thermal barrier and reduces the coil efficiency.

The higher efficient filters will limit
the dust that passes across the coil but an Ultra Violet light C band width
will actually kill the mold, any virus’ and bacteria. It also helps
prevent the drain pan from growing these unwanted critters.

We sell the units to contractors, but since
we are not a licensed contractor, we don’t install.

The lights have been proven to keep coils
clean and performing like new.

Yours,

Walter Golding

[Colin]

you should see what is collecting in those ducts, air feels much cleaner afterwards!

[Groomlakearea51]

The material that causes the dust to stick to a cooling coil is a thin film exuded by mold growing on the coil fins. It also acts as a thermal barrier and reduces the coil efficiency

Tech Minion advised that if you use an anti-bacterial hand soap when doing the coils, it will pretty much inhibit any growth until the next vacuum session. Most techs apparently use a special acid solution which consumers cannot purchase. These chemicals, however, are not recommended for the average homeowner for safety and health reasons. The stuff is called "Coil-Clean", or "Brite-Coil", or something like that. It comes in a concentrate. If not mixed right... or not rinsed off properly, it will eat your coils before your very eyes.....

[david.reed21]

And the eating right before your eyes is if you are lucky. The next worse thing is the acid paricials get into the air steam, and cause all kinds of breathing issues. All joking aside, it has been noted by several techs, including my self, the the improper use of coil cleaning concentrate, especially when it has not been properly cleaned off will cause the vapors to rise and settle into the blower motor. Once this happens, it will eat away a the stater coil in side the blower fan motor and cause it to burn out. Some home owners have been known to get hold of coil cleaning products, but if you have not been properly trained, I highly recomend having someone either comb to you home and perform a cleaning, or clean the coil using a mild soap, and througly rinsing the coil, taking care not to bend the fins. If you bend the fins, use a come to open them back up. Bent fins cause resistance to the air stream, and prevent the evaporator coil from exchanging heat from the air to the refrigerant inside the coil.