hard to find size filter
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  1. #1
    Join Date
    Jun 2004
    Posts
    12
    I'm having a hard time finding a 1X30X24 filter with a merv of 8 or 10.I've been using the blue cheapos and I know thats not good.
    I've searched the web and ace Hdw.is the only place I found my size thats not electrostatic but they don't list merv rating on their site.
    any ideas
    thanks

  2. #2
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Originally posted by grg
    I'm having a hard time finding a 1X30X24 filter with a merv of 8 or 10.I've been using the blue cheapos and I know thats not good.
    I've searched the web and ace Hdw.is the only place I found my size thats not electrostatic but they don't list merv rating on their site.
    any ideas
    thanks
    1" that is merv 8 or 10 is likely too restrictive to allow for minimum air flow,to prevent capacity loss an d possible equipment damage.

    Use the search function above,to read more on filters.

  3. #3
    Join Date
    Aug 2003
    Posts
    906
    http://www.filtersnow.com/compare.x?...4X30&submit=Go

    has the size you want. I have bought their filters several times before, good service and reasonable prices. As you can see from the link, you have a choice of MERV 6-12.
    I have no relationship with them, just a satisfied customer. I like their accumulair series because they can capture a lot of dust before becoming restrictive. Filtrete doesn't last half as long in my experience.

  4. #4
    Join Date
    Jun 2004
    Posts
    12
    pmunier, thank s now another question. should I go with a merv 6 or 8 filter.
    thanks again and I'll add this site to my favorites.

  5. #5
    Join Date
    Aug 2003
    Posts
    906
    Originally posted by grg
    pmunier, thank s now another question. should I go with a merv 6 or 8 filter.
    thanks again and I'll add this site to my favorites.
    That's a hard question to answer, and slightly controversial. It depends on how much airflow the furnace needs, and the current resistance to airflow of the ductwork. Look for a sticker on your furnace, it probably says somewhere "maximum ESP 0.5". That's External Static Pressure, and the ductwork, air filter, and A/C coil all contribute to it. Basically, you can get an air filter with the highest MERV rating that doesn't make the ESP go over 0.5" when the filter is dirty (which is when you decide to change it). It could be 6, 8, 11 or even 12 depending on your particular installation and how often you decide to change the filters -- the higher the MERV the more often you may want to change them. It also depends on the brand of filter and its quality -- I've seen MERV 6 filters that have as much resistance to airflow as MERV 12 filters from another brand.

    I'd suggest you find the air speed at the filter (cfm/area). If the airspeed is not more than about 300 fpm you'll most likely be fine with the Accumulair MERV 8. Just remember to change the filter regularly...

    Example: 1600 cfm (4 Ton system) / (24x30/144 in/ft) = 320 fpm

    Whenever you get a checkup done on the furnace, ask to have the ESP measured. Some people decide that they would rather pay any needed repairs to the furnace (and accept that the furnace won't perform well) and install a high MERV filter than be uncomfortable and suffer from allergies or be on antihistamines all the time.

  6. #6
    Join Date
    Aug 2003
    Posts
    906
    There's a cheap filter gage that can help you decide when to change filters:

    http://www.atlantasupply.com/

    Stock #: FILG99
    G-99 Air Filter Gage

  7. #7
    Join Date
    Aug 2004
    Location
    Howell MI
    Posts
    420

    ?

    can you get 2 15x24x1 with the right merv rating ?
    Hire Me....

    Benny

  8. #8
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    18,836
    The static of your system could be too high with the original filter,have it tested Before you buy a more restrictive filter.Or risk damage to the system from low airflow.

  9. #9
    Join Date
    Oct 2004
    Posts
    110
    Greets!

    Be careful with the high MERV rating filters. Static pressure and temperature rise are very important. Here's a quick, simple test to check if your filter is too restrictive.

    Run furnace for minimum 5 minutes (may require setting stat to 85 degrees or so).

    Check temperature of return air.

    Check temperature of supply air.

    Subtract return temp from supply temp. This is temperature rise.

    Check nomenclature tag (where model/serial is located) and look for temp rise. It is typically a range (ie 30-65 degrees).

    If you're within your heat rise range, you're ok. If you've exceeded it, change to less restrictive filter and check again. If it's still too high-have a tech check the heat exchanger for cracks and amp out the blower. A cracked exchanger is commonly the result of running clogged or restrictive filters as metal is overheated. Amp draw on the motor can also give you cfm, and can indicate a need for higher/lower fan speed. Rely on the tech!

    And check your filter MONTHLY (not 3 months like some marketing geniuses recommend).

    Good Luck!

    cdp3

  10. #10
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Originally posted by cdp3
    Greets!

    Be careful with the high MERV rating filters. Static pressure and temperature rise are very important. Here's a quick, simple test to check if your filter is too restrictive.

    Run furnace for minimum 5 minutes (may require setting stat to 85 degrees or so).

    Check temperature of return air.

    Check temperature of supply air.

    Subtract return temp from supply temp. This is temperature rise.

    Check nomenclature tag (where model/serial is located) and look for temp rise. It is typically a range (ie 30-65 degrees).

    If you're within your heat rise range, you're ok. If you've exceeded it, change to less restrictive filter and check again. If it's still too high-have a tech check the heat exchanger for cracks and amp out the blower. A cracked exchanger is commonly the result of running clogged or restrictive filters as metal is overheated. Amp draw on the motor can also give you cfm, and can indicate a need for higher/lower fan speed. Rely on the tech!

    And check your filter MONTHLY (not 3 months like some marketing geniuses recommend).

    Good Luck!

    cdp3

    With 3M filtrete,run the test again after a week,as the "load up" fast,and can damage the system.

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