Electronic Furnace Filters

This should be an easy one.. I already have an opinion on this but would like to hear more as I could be wrong (not being a air flow expert and stuff).
When deciding between going with an electronic filter vs filter media (assuming cost isn't an issue) which would be better. I've seen how electronic filters are built and I would think that they provide less restriction. However, I've been told the opposite - that filter media provides less restriction than electronic filters... Is that true?
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I have a a HVAC Company, I would not suggest installing a Electronic Air cleaner, besides the cost of the cleaner and installing then they seem to break down alot, and a contractor can not fix them they have to take them to a speclist to have them fix, but they do have lest air restriction, I perfer for my customers to use 3m pleated filters they are high destisy but they are good filters and they do have to be change once a month, Or Use a good eletrostatic filters Newtron have been around a while, Or if you really want a hosptital grade Abatement tech. have some but cost can run 600-1200 depending on who installs it. STravis wrote:

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you would have to be crazy to buy an electronic filter. I pulled mine and use a pleated filter instead. Not only are they difficult to clean and expensive, but expensive to fix.
Of course it is also a matter of your house. My old house had two HVAC systems because of an addition. The electronic filter on the first floor had to be cleaned every few weeks. The one on the second floor could go months.
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Toller wrote:

Not sure which type you had, but most are extremely easy to clean. You pull the collector grids and either hose them down outside, or just run them through the dishwasher. Super easy, just have to make sure they are dried completely before putting them back.
As for fixing, there is little to fix on one. It's just a HV power supply and a collection grid. Considering the power supply is little different than a neon sign transformer and those last decades without failures there is little reason that a quality EP unit should ever need service in any reasonable lifetime.

Total system run time and the cleanliness of the environment will affect the cleaning frequency. Newer addition likely means better insulation and shorter HVAC run times. Sizing of the system and efficiency also would affect run time.
Pete C.
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wrote:

In the middle of a new england winter, hosing them down outside is not realistic. Putting them thorugh the dishwasher works, but only one wil fit in ours at a time, and there are two of them, so you have to run two cycles through the dishwasher. After two cycles you have to wait for the second one to dry. Not difficult, I agree, but annoying, and while you're doing this you are running the furnace without an air cleaner.

I had a Honeywell electronic air cleaner, dates from about 1987. It has a little sensor that detects air flow in the furnace output. That way the air cleaner turns itself on and off without tieing into the furnace fan circuit. When that detector board failed, all you could do was replace it -- for a cost of $500.
I can get good pleated filters that fit in the Honeywell air cleaner "slot", and that's what I use now. Changing them once a year takes about 1 minute.
Another disadvantage of electronic air cleaners is the "snapping" noise that they make when they run. If you have a bedroom right over the furnace, you can hear this and it's pretty annoying.
Terry
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I find that awfully hard to believe.

Let them drip a few minutes, then re-install them and turn on the furnace fan for a few minutes.

I've replaced the supply in a few.

All installations I've seen, the filter is wired to the fan supply. No switch needed.
Bob
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Terry wrote:

Perhaps an earlier design unit, the newer ones seem to be designed to fit the dishwasher ok. A rinse in the bathtub or laundry sink is also an option.
When the grids are out for cleaning you should never be operating without a filter, there should always be a basic media type pre filter in the system. An EP is not a replacement for that pre filter.

A poor design. An airflow paddle switch, a differential pressure switch or a sense line to the fan circuit would all be better. There is also minimal reason not to just leave the unit powered full time as they consume little power.

Filters should be changed more than once a year unless you're in a climate with minimal heating and cooling requirements and you indicated new england which has substantial HVAC requirements.

That snapping should be almost non existent if you have a proper pre filter before the EP. An EP does not "snap" in normal operation, it only snaps when a large piece of debris bridges the collection grids and debris that large would never make it past a proper pre filter. It sounds like your system was not properly configured.
Pete C.

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wrote:

Sure, but you have to clean the pre-filter too. At least you do on our system, they are an aluminum mesh that you rinse out.

the electronic filters, and their prefilters.

I'm not an expert, but this is my experience. And yes, the system does have pre-filters. The snapping would be the worst just after cleaning, then it would get less as the filters got dirtier.
Terry
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Terry wrote:

Odd, I'm not an expert either, but I have some experience with a couple air handlers with EPs at a place I used to work. They were moderate sized Carrier units, not really larger than you would have serving a home since they were serving a couple thousand sq. ft. of office area. I don't recall hearing much snapping ever, and they were doing their job as the grids would buildup a good load of crud.
Pete C.
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STravis wrote:

Electrostatic precipitators aka electronic filters will almost certainly have lower airflow resistance than a media type filter, however you should to have a conventional media type pre filter anyway though it doesn't need to be a fancy high efficiency one. The pre filter will remove larger things like a hair perhaps that could short out the precipitator grid.
Pete C.
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