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  1. #1
    Join Date
    Jun 2012
    Location
    Rockledge, Florida
    Posts
    16

    I can't find 4" filter return grills

    I have a 4 ton Carrier central A/C heat pump with two (2) 20x20 return grilles. Each one holds a typical 20"x20"x1" filter. Yes, I use the high-end 3M filters that get virtually everything. Even when the filters are clean, they slap in pretty hard when I pull them out and release.

    I've seen 4" deep filters of the same size and I'd like to replace my existing set up with two of them. Would it be a good idea or would the extra air volume reduce the evaporator's ability to remove moisture?

    Would it be a good idea for the tech to reduce the speed of the fan motor if I get the 4" filters? Perhaps I can get the same air volume with less power to the fan motor and save on my electric bill.

    Suggestions???

  2. #2
    Join Date
    Feb 2010
    Location
    Cal
    Posts
    1,596
    Jim, there are filters manufactured 4" deep with a 1" x1" lip around the 4 sides. They fit in a conventional filter grill and protrude inwards 4". Check the web. I'll post something on Monday if you have no answers from others by then.

  3. #3
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,626
    Quote Originally Posted by Jim In Florida View Post
    I have a 4 ton Carrier central A/C heat pump with two (2) 20x20 return grilles. Each one holds a typical 20"x20"x1" filter. Yes, I use the high-end 3M filters that get virtually everything. Even when the filters are clean, they slap in pretty hard when I pull them out and release.

    I've seen 4" deep filters of the same size and I'd like to replace my existing set up with two of them. Would it be a good idea or would the extra air volume reduce the evaporator's ability to remove moisture?

    Would it be a good idea for the tech to reduce the speed of the fan motor if I get the 4" filters? Perhaps I can get the same air volume with less power to the fan motor and save on my electric bill.

    Suggestions???
    What size is the duct that goes to the 2- 20" x 20" filter grilles?

  4. #4
    Join Date
    Jun 2012
    Location
    Rockledge, Florida
    Posts
    16
    Quote Originally Posted by George2 View Post
    What size is the duct that goes to the 2- 20" x 20" filter grilles?
    Both filters goes to a big framed-in box that's under the air handler. It's in the garage. I guess somebody had the foresight to realize that 20x20 filters are much easier to find than a single 20x40.

    Somebody here mentioned a 4" deep filter that has a ridge to let it fit in the existing filter box??? I did a quick keyword search and all I saw was regular filters and didn't see this ridge. Brand and/or keyword, please.

  5. #5
    Join Date
    May 2006
    Location
    Philadelphia, PA
    Posts
    1,378
    Honeywell FC40R1003. Should have your contractor verify airflow.
    Climate Control Solutions for your Home or Office

    Serving Northeast Philadelphia and Surrounding Areas

  6. #6
    Join Date
    Jun 2012
    Location
    Rockledge, Florida
    Posts
    16
    Quote Originally Posted by comfortdoc View Post
    Honeywell FC40R1003. Should have your contractor verify airflow.
    I got two of the Honeywell 20x20x4 filters yesterday and put them in. They fit right in the existing filter returns with no fuss. I was able to reduce my fan speed to Medium and it STILL feels like there's more air coming out of the registers than with the old 1" filters and High fan speed.

    Even when the 1" filters were new, they slapped in a little too hard for my liking. Now, there's just enough of a pull to set them in place. I'm sure the SEER of my old Carrier system just got bumped up a full point. In short, upgrading to the 4" deep Honeywell filters are worth the price.

  7. #7
    Join Date
    Mar 2009
    Location
    Mount Holly, NC
    Posts
    3,081
    yup.
    now if i could only convince all my customers of this fact.

    it's amazing how restrictive the 1" filtrete filters are.
    The TRUE highest cost system is the system not installed properly...
    The three big summer hearththrobs...
    Mel Gibson
    Dwane Johnson
    The A/C repairman

  8. #8
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,961
    Quote Originally Posted by btuhack View Post
    Jim, there are filters manufactured 4" deep with a 1" x1" lip around the 4 sides. They fit in a conventional filter grill and protrude inwards 4". Check the web. I'll post something on Monday if you have no answers from others by then.
    Additionally, make sure there is plenty of depth-room in the filter box so it doesn't end-up having an airflow restriction problem...

  9. #9
    Join Date
    Jun 2012
    Location
    Rockledge, Florida
    Posts
    16
    Quote Originally Posted by udarrell View Post
    Additionally, make sure there is plenty of depth-room in the filter box so it doesn't end-up having an airflow restriction problem...
    Fortunately, the original A/C installer built an oversized framed-in box to set the air handler on top of. Large enough to hold two 20x20 intake grills with room to spare.

  10. #10
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,186
    Did the same thing on my ceiling returns. Rebuilt the filter grilles to accommodate the 20x20x4 filters. Excellent results, I left my fan on high speed. Unless you have humidity issues or have verified airflow, high fan speed typically is the best setting. Most ductwork is undersized and needs all the help it can get. Energy savings from reducing fan speed is minimal according to my kill-a-watt meter. 500W on high, 380W on low for my 1/3HP blower.

  11. #11
    Join Date
    Jun 2012
    Location
    Rockledge, Florida
    Posts
    16
    Fortunately, my air handler has a three speed fan. I'm sure Medium speed is somewhere between 500W and 380W.

    Yep, the humidity is suffocating where I am, on the east coast in Florida. I'd run the air handler fan on Low speed if I thought it could keep the house cool AND remove even more of this awful humidity!

  12. #12
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,186
    My furnace has a 4 speed fan, I just wanted to illustrate how little difference there is in power consumption between the lowest and highest speeds. Airflow changes considerably, power consumption not so much. You will loose more in condenser efficiency that you gain in blower savings.

    PSC motors take a big hit on efficiency when operated at part load. Variable speed blowers really save energy on lower speeds, some use less than 100W on low.

  13. #13
    Join Date
    Jun 2012
    Location
    Rockledge, Florida
    Posts
    16
    Quote Originally Posted by 54regcab View Post
    My furnace has a 4 speed fan, I just wanted to illustrate how little difference there is in power consumption between the lowest and highest speeds. Airflow changes considerably, power consumption not so much. You will loose more in condenser efficiency that you gain in blower savings.

    PSC motors take a big hit on efficiency when operated at part load. Variable speed blowers really save energy on lower speeds, some use less than 100W on low.
    O.K., I'm getting a new education here. Even my old Carrier heat pump will be more efficient if the air handler fan is on high speed? The humidity in my house dropped only 3% since making the changes yesterday i.e. the new 4" filters and slower fan speed. Of course, I haven't received my electric bill yet to see if there's any difference.

    So, all else being equal, the air handler speed should be on High to get the best cooling for the money? Seems counterintuitive but, I'll take your word on it.

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