ReplyIf its MERV rating is high enough, and you run the fan virtually 24/7, they do make a big difference.
Regular Guest
I am in the process of having an Aprilaire whole-house humidifier installed and the contractor was also telling me about the Aprilaire Model 3410 Air Cleaner (with Even-Based Cleaning) and the Model 5000 Air Cleaner (EAC). I've spent some time in this forum and have read various opinions about air cleaners in general.
Well, do they work in reducing symptoms of asthma and allergies?
One HVAC professional in this forum who didn't believe in air cleaners said that the amount of "dirt" you collect from the Aprilaire filter at the end of the year is minimal when compared to the amount of dirt you collect from your vacuum cleaner (if you total the whole year). He said this to illustrate that air cleaners in general don't filter much dust and allegens.
Another HVAC professional suggested that HVAC systems in general don't generate enough pressure to be good air cleaners.
What do you guys think?
God Speed, Jim. We'll miss you - 2-26-23
If its MERV rating is high enough, and you run the fan virtually 24/7, they do make a big difference.
Regular Guest
I think I found an answer to this question from a nice literature review from the EPA:
It does seem that whole-house air cleaners can reduce concentrations of small particles but may not necessarily reduce symptoms of asthma and allergies. Attached below is the whole document from the EPA. It makes for a nice reading. But this is the most pertinent part:
Will Air Cleaning Reduce Health Effects from Indoor Air Pollutants?
Air-cleaning devices may help reduce levels of smaller airborne allergens, particles, or, in some cases, gaseous pollutants in a home. However, air cleaners may not decrease adverse health effects particularly in sensitive populations such as children, people with asthma and allergies, and the elderly.
Clinicians frequently recommend that patients who have asthma or allergies use HEPA air filters in HVAC systems or in portable air cleaners. Regardless of how efficient and effective air- cleaning devices are in removing pollutants, a question still remains about their ability to reduce adverse health effects.
How effectively air-cleaning devices alleviate allergic and other health symptoms remains uncertain. Strong data linking air-cleaning devices to reduced health symptoms do not exist. Many studies have associated air-cleaning devices with reductions in airborne indoor pollutant concentrations, but more clinical studies are needed to determine whether air cleaners significantly affect health outcomes. A literature review documented only a limited number of studies that attempted to evaluate the clinical outcomes of air cleaner use. These studies focused on more sensitive groups, such as asthmatic and allergic individuals, children, and the elderly. A number of the studies had important limitations, such as small study size, short duration, and lack of blinding (i.e., subjects and scientists were aware of air cleaner operation), which may result in a placebo effect. The results were also more suggestive than conclusive.
Many indoor pollutants related to asthma and allergies are either airborne particles or irritants, such as the gaseous components of secondhand smoke or nitrogen dioxide, chemicals linked with gas cooking appliances, fireplaces, wood stoves, and unvented kerosene and gas space heaters. Most studies involving subjects who have perennial and seasonal allergy or asthma symptoms tested portable air cleaners equipped with HEPA filters.
Few studies tested gas-phase filtration and air cleaners using UV light technology, such as UVGI cleaners and PCO cleaners. The scarcity of data results in little scientific evidence that these devices are associated with a reduction in health symptoms.
The effects of particle air cleaners on allergy and asthma symptoms have been reviewed by the Institute of Medicine (IOM) Committee on the Assessment of Asthma and Indoor Air of the National Academy of Sciences.26 The IOM concluded that:
The use of air cleaners may help reduce levels of smaller airborne allergens or particles, but should not be expected to effectively reduce health symptoms.The results of existing experimental studies are inadequate to draw firm conclusions regarding the benefits of air cleaning for asthmatic and allergic individuals…. Air cleaners are helpful in some situations in reducing allergy or asthma symptoms, particularly seasonal symptoms, but it is clear that air cleaning, as applied in the studies, is not consistently and highly effective in reducing symptoms.
Several factors should be considered in evaluating whether an air cleaner is beneficial in alleviating health effects.
- Many studies on the health benefits of air cleaning involve multiple interventions and thus are not useful in determining the effects of air cleaners alone.
The health benefits of air cleaners are often studied along with other interventions such as mattress and pillow covers, exclusion of pets from the bedroom, weekly baths for pets, or vacuum cleaning. Studies that consider air cleaning concurrently with other interventions have relatively little value in determining the clinical outcome resulting from the use of air cleaners because it is not clear if any improvements demonstrated are due to the air-cleaning devices or to the other interventions.
- An air cleaner’s ability to remove some airborne pollutants, including microorganisms, is not, in itself, an indication of the air cleaner’s ability to reduce health symptoms.
As discussed previously, pollen, dust mite and cockroach allergens, some mold spores, and animal dander carried on large particles settle rapidly before they can be removed by filtration. Because these particles do not remain airborne, air-cleaning devices are relatively ineffective in their removal.9, 26, 60 Therefore, effective allergen control requires routine cleaning and dust control including the weekly washing of bed sheets, frequent vacuuming of carpets and furniture, and regular dusting and cleaning of hard surfaces. (For more on allergen control, visit www.epa.gov/asthma)
A significant fraction of cat and dog allergens and a small portion of dust mite allergens associated with mite feces are carried on small particles. Consequently, they are more easily dispersed throughout a house, remain airborne longer, and are more likely to be removed by air cleaners.23, 61 Although there is evidence that some air cleaners can remove a portion of smaller particles from the air, there is little evidence that these reductions in particle levels alleviate health symptoms. This lack of improvement in symptoms may be due in part to the fact that, once sensitized, allergic and asthmatic individuals respond to much lower levels of pollutants.
There is little clinically confirmed support for the effectiveness of UVGI cleaners in reducing health symptoms in either airstream or surface applications. Despite UVGI’s ability to deactivate some surface-grown microorganisms, data linking the effectiveness of UVGI systems to reduced health symptoms in sensitive populations such as children, asthmatic and allergic individuals, and the elderly are not available for residential settings.
- Some air cleaners may produce new, potentially toxic pollutants or may re-disperse old ones.
A limited number of studies report that irradiation by UVGI lamps reduce vegetative bacteria and molds that are either airborne or growing on moist HVAC surfaces.34, 39, 40, 43, 44 However, the dead mold spores may still cause allergic reactions in some people.
High moisture and elevated temperatures can promote bacteria and mold growth in particulate filter media.35 Air filters may re-emit bacteria and mold spores during HVAC startup and off-and-on operations when air velocity suddenly increases.37
Ozone generators sold as air cleaners for use in occupied indoor spaces produce ozone, a lung irritant.8 Electronic air cleaners, such as ion generators and electrostatic precipitators, have the potential to emit potentially dangerous levels of ozone.5, 22, 29 Contamination of electrode surfaces in electronic air cleaners may cause increased ozone levels.62 There also have been reports of electronic air cleaners producing fine particulate material from the reaction of ozone produced in the corona discharge with other chemicals indoors.9, 10, 63
Liquid tobacco smoke particles trapped by an air filter may give off odorous organic gases.12 Saturated sorbent filters may also release trapped gaseous pollutants back into the airstream.31 If a PCO system’s design parameters do not match the pollutant targeted for decomposition, the PCO cleaner may create, as a result of the oxidation process of certain VOCs in indoor air, by-products that are indoor air pollutants.
Current evidence suggests that air cleaning may have a useful role when used in conjunction with source control and ventilation with clean outdoor air.
Professional Member*
Ozone
Always here
Professional Member*
this is your recommendation?Originally Posted by energy star
from the article OP posted:
Ozone generators sold as air cleaners for use in occupied indoor spaces produce ozone, a lung irritant.8 Electronic air cleaners, such as ion generators and electrostatic precipitators, have the potential to emit potentially dangerous levels of ozone.5, 22, 29 Contamination of electrode surfaces in electronic air cleaners may cause increased ozone levels.62 There also have been reports of electronic air cleaners producing fine particulate material from the reaction of ozone produced in the corona discharge with other chemicals indoors.9, 10, 63
I'd re think that recommendation.
__________________________________________________ ____________________________________
OP, if you seal the air leaks in the house where air enters
and then the ductwork & returns of the central system, you
make great headway into reducing particulate matter into your home.
less VOC's entering, less to 'clean' out of air.
this is a stragegy that works.
if you have recessed lights that are not ICAT, then you have leaks into
the attic where air is filtered through the insulation on the attic floor
and then enters the house.
if your return air isn't sealed, it sucks dust & insulation particles into the house.
if supply boxes, ducts, bath fans ...aren't sealed....
depending upon where the leaks are, different voc's are brought into the house.
things like types of insulation in attics and walls play into what type of voc enters
through the leakage areas.
I've found that by sealing the house & duct/retrun leakage..allergies & asthma issues
are lessened. as more leaks are sealed, most symptoms are also abated.
doesn't make a difference when you go outside..but in the home, you can control
what enters from where.
having a diagnostic testing of house, ducts, returns etc is a good start.
look for someone who does blower door and duct testing diagnostics.
here is one place to start
www.resnet.org
make sure whoever you hire has experience in diagnostics and your
specific issues. rather than spending lots of $$ on air cleaners that have
minimal effect, make a few calls to building envelope specialists that
understand duct & return leakage issues.
sealing leaks into attic would be my first priority. then ducts & returns.
even openings where supply grills attach are badly cut. same with bath
fans. attached is a picture of a supply grill that has been sealed with mastic tape.
before sealing there was a 1/4 to 1/2" gap all around the box hidden behind
supply grill.
best of luck
The cure of the part should not be attempted without the cure of the whole. ~Plato
Professional Member*
Biggest difference is getting a very good vacuum cleaner with a HEPA level exhaust filter on it and vacuuming at least weekly. If possible, remove carpeting and go to hardwood or tile floors.
Sealing return duct is definitely a big plus.
Professional Member*
Sealing or replacing ductwork is usually the most effective way to reduce dust in a home as well as sealing thermal bypasses and leaks in the thermal envelope (can lights, plumbing penetrations, electrical penetrations etc.) of the structure then after that is done you can install a high merv or whole house filtration system as well as mechanically bringing in fresh air to purge indoor pollutants. An energy audit aka blower door test will pin point the trouble areas in your home. www.comfortinstitute.org and www.bpi.org are good resources for further research.
Professional Member*
or Resnet.us
just cause I'm resnet...
best of luck.
The cure of the part should not be attempted without the cure of the whole. ~Plato
Professional Member*
No. MY POINT WAS EAC PRODUCE OZONE!!!!! WATCH WHAT YOU BUY
HELLO!!!
get it right rater!
Always here
Professional Member*
Obviously Good, Keep_It_Simple advice.
I prefer, use and KNOW that portable HEPA 99+% air cleaners Work for me.
http://www.hunterfan.com/Products/Ai...EPAtech-30378/
I certainly would not refer to HEPA air cleaners as _quiet_.
... Buyer Beware. Store test necessary if you're concerned.
Of course, some people prefer the "white noise".
Designer Dan __ It's Not Rocket Science, But It is SCIENCE with Some Art. _ _ KEEP IT SIMPLE & SINCERE ___ __ www.mysimplifiedhvac.com ___ __ Define the Building Envelope & Perform a Detailed Load Calc: It's ALL About Windows & Make-up Air Requirements. Know Your Equipment Capabilities
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