Hello,
I suffer from multiple allergies (and having dogs in the house does not help). I know that there are several electric air cleaners out there that are installed on the air return duct.
Any suggestions on which brands are better than others? And can these be installed by someone who has moderate handyman skills (me)?
Thanks in advance! Steve
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Replies
I'm not a AC or duct man but from what I have seen installing the circuit for these units it would seem that as long as the duct situation is doable it isn't that big, or complicated a job.
The duct is mostly cutting out a section. Installing short transitions and/or flexible sections to match the unit. Screwing everything together and sealing.
The electrical side is a s simple as finding or running a place to get 120v that can handle the 5A or so of load. Either an existing receptacle or a new circuit. I, being an electrician, usually go for a new circuit if there is room in the panel.
Steve,
Ours is installed right at the furnace where the return air duct attaches. Its about 6 inches thick. Ours is a Honeywell. We had it put in when we replaced the furnace about 4 years ago and my Wife swears there is much less dust.
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
She is just saying that so she dose'nt have to vacuum as much.;-)
You might want to do some more research on this.
I believe that the current think that HEPA media filters are much better.
Steve,
If you're talking about electrostatic air cleaners, I'd recommend not going there.
An electrostatic air cleaner (also known as an electrostatic precipitator, or ESP) works by running the air past an array of parallel wires at a few thousand volts to create a static charge on the particles, and then collecting the dust on parallel plates (of the opposite charge) just a couple of inches downstream in the airflow.
This high voltage has an undesirable side effect--it turns a little of the oxygen in the air into ozone. While the ozone output of a well designed and properly operating ESP is very low, any ozone is not good for human lung tissue. It's an oxidant and although it smells good ("fresh", like after a thunder/lightning storm), even very low concentrations irritate and damage lung tissue.
There are health protective standards set by various public health agencies like the US EPA for ozone in outdoor air. Supposedly if the ozone concentration is below the air quality standard value, any damage that occurs is considered reversible--that is, the body will heal itself. The standards are set in consideration the fact that people spend most of their time indoors, where the outdoor levels of ozone are scrubbed out of the air by reacting with walls and stuff inside.
The ozone outside comes from the reaction of hydrocarbons (like from car exhaust and gasoline spliiage), oxides of nitrogen (mostly from internal combustion engines), that is cooked by sunlight. Ozone is the main component of smog.
Now the ozone output of an ESP air cleaner is such that the resulting indoor concentrations will be lower (sometimes much lower) than the ambient (outdoor) standard would indicate is "safe". But you're exposed to that indoor ozone all night. Not good. So I'd recommend not getting or using an ESP air cleaner.
If you want to use an ESP and tolerate the ozone, from a practical standpoint if you have dogs with coats of moderately long hair, the ESP won't work well. Even with a good pre-filter upstream of the ESP, hair will get through and short out the ESP in a minor way, and reduce it's efficiency. I have two Golden Retreivers with long hair, and the ESP wires and plates are pretty fouled with hair when I clean them (quarterly). I don't use the ESP, it's turned off, so it doesn't matter; but if I did want to run it, I'd have to use a maximum efficiency prefilter and even then, probably replace the prefilter monthly and clean the ESP units weekly.
I'd recommend using a HEPA (high efficiency particulate, air) filter in the return just in front of the air mover, and changing it out regularly. Or maybe even putting moderate-efficiency filters at the intake of the return vent(s), and a HEPA at the furnace blower.
On another note, if you haven't already, find a good allergist. A good one can really made a difference in the quality of life.
Cheers,
Cliff
There is a lot of discussion on this topic at http://www.hvac-talk.com - check out the Indoor Air Quality threads. DW and I have allergies and dogs as well. We decided to go with a media filter instead of electronic because of the ozone issue and also because they need to be cleaned religiously. I just know us - after a few years we'll get lazy and the air quality will go down the tubes - the pro's say they see a lot of very dirty ducting in homes with electronic filters.
We just replaced our two furnaces and I agree with the others - avoid the electrostatic cleaners. I was thinking about getting a combo unit, but decided to go with the six inch media filters instead and I'm glad I did. Besides the ozone problem, if you don't keep them clean they will short out and you get popping noises, which creates more ozone.
Steve
Stop drinking milk, see if that makes allergies go away. I know 10 people who have no more hayfever.
I have designed the air conditioning and heating systems for a few medical operating rooms, clean untility rooms and recovery rooms for post operative patients. One thing that I have never seen in a hospital or clinical air system is an electric air cleaner.
What I would recommend is the Honeywell Envirocare Elite media air filter or the April Aire Space Guard media air filter. These consist of a 4 or 5" thick pleated air filter that you replace as necessary, once or twice a year. Some come wth the option of a "clogging indicator" to assist in determining when a change is warranted. The replacement elements are not cheap, but far superior to anything else.
Edited 5/18/2005 7:05 pm ET by Timbo
Depends on your ductwork and the cleaner. Some are designed to slip in in place of a regular filter, but most are thicker than that and require some tin bending.
You need a section of return air duct that is straight for the required distance (filter thickness), and is of the required cross-section. Unfortunately, in most cases the duct does a 90 right at the furnace, with little space adjacent to the furnace to add anything, and often the vertical duct is too small for the filter (even if the filter is allowed to be installed horizontally, which isn't a given).
If there is sufficient space in the ductwork, you still have the problem that doing the job right will generally require special tools and a modicum of skill/experience. (However, some units may be designed for HO installation and may be installable without the special tools.)
Go to the mfgr's web site and see if they have the installation instructions online as a PDF. This will help you determine if you can make things fit and if you have the required tools/experience.
PS: I'd agree with the others that you'll probably be better off with a media filter of some sort. Even the standard pleated filters are tons better than the old-fashioned fiberglass filters, and you can get much more sophisticated than that without having to go electronic.
I have two ESPs, and can give you several reasons not to use them.
1. Unreliable. I've had mine for 12 years, and they've had to be repaired more times than I can count. Door switches, flow switches, circuit boards, wires. I've had them all go bad, the ckt board multiple times, as well as the door and flow switches. The ckt boards are $250 a pop, just for the board. Time for the HVAC guy (who can order the part, but not I, cause I don't have a Trane distributer's license) to replace the board rockets the bill to about $500. Each time. Must have replaced 4 or 5 of them in the last 12 years. One isn't working now, and I told the service tech to leave it be, I am gonna switch to a HEPA filter.
2. Money. See #1. above.
Don't do it. Period.
Edit: My wife and kids have bad allergies. She got the doc to prescribe a change in air environment in the house. I used that come tax time to write off about 20% of the cost of the systems, which total ran about $20K. Check into it.
Edited 5/18/2005 10:14 pm ET by NickNuke'em
Consumer reports just did a review of some of the portable ones. The sharper image electonic type unit that is heavily advertised was rated poorly. It emits too much ozone. There was one electronic type that had acceptably low ozone output. It seemed that they recommended HEPA type instead though. They hinted that you really are better off controlling the source of the allergens than having an air cleaner. The interesting thing that they noted is the certifications that many of the brands advertised sound like scams. I don't remember the names of the certifications, but something like American Asthma and Allergy Institute...ETC. They found that the manufacturers just pay a few thousand dollars to use the symbol. The organizations don't neccessarily do any testing, or provide anything to the public other than a decieving label.
From my read, Consumer Reports seemed to like:Whole House, electronic: (Rated excellent) Aprilaire 5000, Carrier EACA, Trion SE1400Simple Filter (NOT MEDIA/HEPA): (only rated good) 3M Filtrete Ultra 1250and for stand-alone, in-room filters:
Friedrich C-90A (a homely, if effective unit, especially when we leave it on all day at the start of allergy season in a closed room); then Kenmore 83202 83200, Whirlpool AP51030HO and Whirlpool AP45030HOFor whatever it's worth.Interestingly, I distinctly recall that diseases like Legionnaire's disease (a lung infection) get their start in damp air conditioning ducts. Perhaps that's why there are some hospital systems that appear to use high intensity ultraviolet light in the ducting to zap any fungi, viruses or bacteria that seem to be wandering by....in addition to filtration...The other interesting thing is that nuclear subs, which have to be self-contained for their entire patrols (and have industrial lubricants, smoke, odors, dust, etc moving through their air systems)---they use electrostatic air cleaners to scrub particulates rather than replaceable filters (they use a totally different technology for handling CO2). Of course, they have what may be some unique reasons to do so; essentially, a total lack of storage space; difficulty in disposing of used filters without creating quite a noisy fuss; essentially limitless electrical power to power the filters (hey, they are NUCLEAR submarines) and a desire to use a non-clogging technology.Indeed, Trion is apparently the supplier to the Navy...Random, perhaps interesting, stuff...NotaClue