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  1. #92
    Join Date
    Mar 2013
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    Billington Heights, NY
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    Quote Originally Posted by Cdhw8791 View Post
    Thank you so much for responding!

    So, just to be clear...

    When the carbon filter in the Austin Air is full it will retain any collected VOCs and will not redistribute them back into the room? But any new/additional VOCs will simply pass through/not be trapped and retained in the filter (since it’s full)? that's correct

    OR

    When the carbon in the Austin Air is full the carbon will begin to break down and any collected/trapped VOCs will be released back into the room? carbon will only break down under high heat of combustion. not room heat. once saturated it just sits there, pretty much inert.

    I’m sorry I’m not terribly knowledgeable on the subject and am deeply concerned as I’ve had the HealthMate Plus in our bedroom for 4 years. I never noticed a smell until I read online that a smell was an indicator that the filter needed replaced. I immediately turned on the unit and let it run for a while and went back to check on it only to find that indeed a sweet smell was coming from it. I’ve been concerned that any trapped VOCs have been released (if that’s possible) making it pointless to have ever used the unit at all. It’s supposed to cover 1500 square feet for 5 years under normal circumstances. The unit is in a 400 square foot room with the doors closed in a room that is smoke free and hasn’t had new carpet or new paint in more than 15 years. A call to Austin Air didn’t leave me feeling confident that they had any idea one way or the other.
    a sweet smell is usually an indication of mold or mildew odors.


    Experience - knowing when to get the hell out of the way and plug your ears. "Don't be a sissy. Turn it on!"

    Poodle Head Mikey - "the world is well populated with the unknowing and the uncaring and the stupid."

    Jtrammel - "Im going to sell hvac systems derp derp derp"
    BBeerme - "every time he opens his mouth, he reminds me of a cow without the fart bag."

  2. #93
    Join Date
    Jan 2018
    Posts
    3
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    Thank you so much! This is very helpful. Id love to know more about what another poster (randyf) on here meant when he said:

    Caveats of the Austin unit:
    3. Carbon is known to re-spew the adsorbed VOCs during some conditions. Not sure of details and how important that is.

  3. #94
    Join Date
    Mar 2013
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    Billington Heights, NY
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    Quote Originally Posted by Cdhw8791 View Post
    Thank you so much! This is very helpful. I’d love to know more about what another poster (randyf) on here meant when he said:

    Caveats of the Austin unit:
    3. Carbon is known to re-spew the adsorbed VOCs during some conditions. Not sure of details and how important that is.
    Carbon will release its adsorbed VOCs when it's heated excessively (not high room temps - hundreds of degrees), reactivated by high power UV lighting, when it's wet (like pouring water on it), or when a chemical that reacts with carbon comes into contact with it.
    Experience - knowing when to get the hell out of the way and plug your ears. "Don't be a sissy. Turn it on!"

    Poodle Head Mikey - "the world is well populated with the unknowing and the uncaring and the stupid."

    Jtrammel - "Im going to sell hvac systems derp derp derp"
    BBeerme - "every time he opens his mouth, he reminds me of a cow without the fart bag."

  4. #95
    Join Date
    Dec 2015
    Location
    Austin
    Posts
    123
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    Thread Starter
    Quote Originally Posted by Cdhw8791 View Post
    Thank you so much! This is very helpful. I’d love to know more about what another poster (randyf) on here meant when he said:

    Caveats of the Austin unit:
    3. Carbon is known to re-spew the adsorbed VOCs during some conditions. Not sure of details and how important that is.
    Sorry I just saw your question.

    Carbon filters can release previously trapped VOCs under a number of conditions:
    1. If the filter is saturated and out of room for any more storage.
    2. Carbon is not an equal opportunity players. It likes some VOC better than others. A more favored VOC can replace a previously trapped VOC.
    3. Heat - And the heat does not have to be to high I recently reported that heated up the room I was testing from 72 to 82 caused a rapid release of previously trapped VOCs. This was quite a shock and I bought a new filter.

    Big commercial operations will test for filter saturation by weighing the filters. They actually accumulate enough VOCs to show the difference on a scale.

    There are some non-carbon adsorbent materials that claim not to release previously stored gases. That's a whole other ball game

  5. #96
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    8,661
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    My recollection of carbon filtering is as follows.
    Carbon material is activated by loading with steam with which displaces any of vocs that carbon is able to adsorded.
    Heating and driving the moisture from the carbon activates the carbon.
    Forcing air through the carbon allows the carbon to adsorb the volitle organic compound until loaded.
    When at capacity, the carbon stops removing vocs and levels the concentration of vocs passing through the material.
    If relatively pure air is flowing through the material, a small amount of vocs are released to the air. If this continued, all of the vocs would leave the carbon and pass to the air flowing through the filter. Also the amount of moisture in the air effects the amount of vocs released. More moisture, more vocs released. Saturation of moisture and heated dry purges all of the vocs. I am sure this info is on the net.
    So when carbon is loaded, it levels the vocs flowing through the carbon. Change it or re-activate it with steam and heat.
    If some one finds tech article, post it.
    It really works.
    Number one, get fresh air change to renew oxygen and purge indoor pollutants. Using active charcoal works but requires large amounts of charcoal and changing/reacitivating routinely.
    Keep the charcoal dry by circulating <50%RH air through the filter to avoid release vocs into the air.
    It does not replace the oxygen we need. In nature, green plants do that. An air change in 4-5 hours will do that.
    REgards Teddy Bear.
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  6. #97
    Join Date
    Dec 2015
    Location
    Austin
    Posts
    123
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    Thread Starter
    Quote Originally Posted by Cdhw8791 View Post
    If, when the carbon filter is full, it redistributes the absorbed VOCs back into the air- isnt this a big concern? I have an Austin Air HealthMate Plus and assumed I would not need to change the filter for 5 years. After 4 years of use I read on other sites about consumers worried that the Austin Air was actually emitting VOCs if the filter was full and therefore doing more harm than good. The problem is - how do you know when the filter is full? Id love to hear if you have any information on how one can detect when the filter needs to be changed (rather than going by an estimated 5 year average). It seems like these things could be really bad if used with a full filter. And what if your filter is full after on three years but you just dont know it because you estimate five years? Thanks so much for your help!
    I'm on my 3rd Austin Filter (healthmate+). First one I changed after 3-4 years after I moved to an environment with High VOCs and wanted a fresh start. That was about 3 years ago. Recently replaced this filter when I was measuring VOC levels with an industrial PID meter. The filter was effective a ~72^F. Less VOCs coming out than going in. Increased heat to ~82 and More VOCs were coming out than going in. The Austin Unit was releasing previously trapped VOCs into my living space. It was making matters worse. I ordered a new filter directly from Austin and they applied a discount because I was replacing before 5 years.

    I was aware of issues of carbon releasing VOCs, but I was stunned when I actually measured it. Keep in mind that the filter was effective when temps were in the low 70s Curiously, as you reported, the older filter has a slight "sweet smell". i found it very curious that the Austin unit was effective until the heat was increased. Then it wasn't just ineffective, it spewed more VOCs in my living space than I started with..

    Keep in mind that all decent high end carbon filters also include non-carbon *additives*. This is usually potassium peregrinate, but Austin uses potassium iodide. Curiously enough these additives are oxidizers that break down VOCs in a similar manner, but different implementation, than PCO devices (MoleKule, RGF, Air Oasis ect,ect). Carbon's effectiveness varies depending on the specific VOC. These additive are intended to fill the gap. These additives, like carbon, degrade with usage.

  7. #98
    Join Date
    Mar 2013
    Location
    Billington Heights, NY
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    Quote Originally Posted by teddy bear View Post
    So when carbon is loaded, it levels the vocs flowing through the carbon. Change it or re-activate it with steam and heat.
    If some one finds tech article, post it.
    https://activatedcarbon.com/services/reactivation/

    https://www.watertechonline.com/exte...ivated-carbon/

    The temperature of the process is described in this page near the bottom:

    http://www.evoqua.com/en/brands/IPS/...recycling.aspx
    Experience - knowing when to get the hell out of the way and plug your ears. "Don't be a sissy. Turn it on!"

    Poodle Head Mikey - "the world is well populated with the unknowing and the uncaring and the stupid."

    Jtrammel - "Im going to sell hvac systems derp derp derp"
    BBeerme - "every time he opens his mouth, he reminds me of a cow without the fart bag."

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