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  1. #14
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    Quote Originally Posted by dash View Post
    No comments on robo's opinion??

    You guys are way above me when argueing airflow, so I stay out...
    If everything was always done "by the book"....the book would never change.

  2. #15
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Care to guess who is correct??

  3. #16
    Join Date
    Jul 2005
    Posts
    717
    Quote Originally Posted by smokin68 View Post
    Easier to change out in a filter grill and keeps the ductwork cleaner, so my preference.
    ************************************************** *****

    On most typical forced air duct systems there could be numerous return grilles placed thru out the home. Having filters in each of these grilles would be a waste of time and money to replace them,whereas having a properly sized filter right at the furnace would make it so much easier and less costly to replace.

  4. #17
    Join Date
    Dec 2007
    Location
    Cedar Grove, Wi-Sheboygan
    Posts
    1,582
    I just finished installing a electronic air filter on my furnace yesterday, and after installing the air cleaner I taped all the joints around the return air ducting, ever joint and screw hole that I could see and after doing so I could feel the difference in air circulation immediately, not to mention I also noticed a difference in the running of my furnace as well. If you have ever taken apart a return air duct you would simply be amazed by the amount of dust in the ducting, I was !!!! I vacuumed the return duct as far back as I could before putting everything back togeather when cleaning the ducting I had approximately a good 1/4" of caked dust on the bottom side of the duct work, But in saying that I have to tell you that my duct work is about 25yrs old most everything is only 2 maybe 3 piece sections of heavy gauge sheet metal. I will let you know how the Electronic air cleaner fairs in about a month or so.

  5. #18
    Join Date
    Oct 2007
    Location
    Southern Ontario
    Posts
    44

    hopefully a pro will chime in...

    Sorry I'm not pro enough for you.....

    Give me a call when you find a perfectly sealed duct. Maybe a pro can come and do a test for the proper seal, maybe get them to install the filter rack for you while they're there.

  6. #19
    Join Date
    Feb 2001
    Posts
    447

    Smile

    I meant no disrespect. Thanks for your input, and Happy Holidays.

  7. #20
    Join Date
    Nov 2007
    Location
    Washington State (on the Peninsula)
    Posts
    80

    sealed ducts

    Properly sealed ductwork is very important no matter where the filter is located. The duct leakage test is an important step in commisioning any new system. Most of my systems include an air purifier, so it will be at the furnace location.
    Yes, I am always amazed at the amount of dust I find in some old system's ductwork.

  8. #21
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    238
    I have a 28x30x2" MERV 11 filter at my air handler and the cheapest blue filters I can get for the grills. The grill filters are there to catch the big stuff and help keep the ducts clean and to make that expensive behemoth of a air filter last longer.

  9. #22
    Join Date
    Nov 2007
    Location
    Chesapeake,Va.
    Posts
    40
    If it's a new install with new duct work, I would use filter return grills.( keeps the new duct from getting dirty in the future). If using existing duct that has already built up dust,I would just change it at the furnace.

  10. #23
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Quote Originally Posted by drsmith012 View Post
    I have a 28x30x2" MERV 11 filter at my air handler and the cheapest blue filters I can get for the grills. The grill filters are there to catch the big stuff and help keep the ducts clean and to make that expensive behemoth of a air filter last longer.
    Doubling up on filters is fine,IF the Resistance of the filters was taken into account in the duct design(Man. D).

    Addings additional filters ,or better filters,isn't a good idea ,without testing first.

  11. #24
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    238
    I would like to have a bigger grill upstairs but with the cheapest least restrictive filter I can buy there is not much additional restriction when compared to an empty grill (tested with a manometer). My returns are very short and dump into approx 28x30" return plenum. The face velocity for the merv 11 at 1300 CFM is 222Ft/min, Which is off the charts, low side, of every filter manufactuer who publishes their initial resistance, but the system normally runs at 900 CFM. I have a manometer on the merve 11 but it also gets the heatexchager too. 8 months on the filter and the coil is still 60-70% of the pressure drop of .22" on low. Haven't been on high yet this year.

  12. #25
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Quote Originally Posted by drsmith012 View Post
    I would like to have a bigger grill upstairs but with the cheapest least restrictive filter I can buy there is not much additional restriction when compared to an empty grill (tested with a manometer). My returns are very short and dump into approx 28x30" return plenum. The face velocity for the merv 11 at 1300 CFM is 222Ft/min, Which is off the charts, low side, of every filter manufactuer who publishes their initial resistance, but the system normally runs at 900 CFM. I have a manometer on the merve 11 but it also gets the heatexchager too. 8 months on the filter and the coil is still 60-70% of the pressure drop of .22" on low. Haven't been on high yet this year.

    Heat Exchanger is already fiqured in the specs.

    Where are you testing the static,ever test the total supply and return??

  13. #26
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Quote Originally Posted by Dave-B View Post
    Properly sealed ductwork is very important no matter where the filter is located. The duct leakage test is an important step in commisioning any new system. Most of my systems include an air purifier, so it will be at the furnace location.
    Yes, I am always amazed at the amount of dust I find in some old system's ductwork.

    As Robo indicated,filter grilles cause more static in the return duct ,so it is more important as return duct leakage,if any will be increased with the higher static due to filter grilles versus one in the furnace.

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