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  1. #1
    Join Date
    Apr 2010
    Posts
    62

    Return air setup on new install.

    I've been reading this forum for several weeks before I finally registered. I have gained a lot of knowledge that I did not previously have.

    There are some things however that I'm not too certain about and hoping that I can be pointed in the right direction.

    First, a bit of history about my setup:

    I live in a 1956 ranch style block home in the deep south. No insulation in the walls (plaster), oak wood floors, double pane windows, black roof, southern exposure. Return ducts: 1 in the living room that was 14x23 and in the hallway about 10 feet away was 14x14. I always had to get custom-cut filter media for the filters as they were not a normal size. The media I used had an orange tacky-like coating on the front to help control the excessive dust problem we had (More on that later)

    The old system was a 2.5 ton Lennox B25 outdoor unit matched with a Lennox 3-ton air handler (in the attic). The unit was 16 years old and worked ie: it blew cool air. The house would never get below 79 in the summer, and would barely keep it 72 in the winter. That's with it running 15-20hrs a day, everyday. I always had yearly checkup's and cleaning done. The duct work had no leaks in the attic that I knew of for the past 10 years.
    I did however get insulation blown in the attic (about 9" worth) and that reduced the run time on the a/c from a 24/7 to 15-20hrs per day. Humidity inside was 65-70%.
    I did not know any better and figured that's just the way it is.

    Fast forward to about 2-3 weeks ago:

    The blower motor woke us up late one night making a hell of a noise. That morning I was going to simply swap the blower motor out, or so I thought. I opened up the portion of the air handler that housed the blower and discovered it was absolutely slam full of mold. That explains why we have all been sick off and on for months, and kept seeing small black balls of "stuff" coming out of the vents. At this point I decided to start getting estimates on replacing this thing.

    Many estimates later and contractors I settled on a local contractor that has been around for just over 40 years and has great reviews. Everyone seemed to want to do a hack job but this guy. I sign the contract and they were out in two days.

    The new unit is an Amana 3-ton ASZ-14 with a ASPF31376 air handler.

    They removed the old air handler with no problem and began to remove the old air intake that was in the living room. It basically was a 3-sided plywood box with no duct inside. No joke. It had been pulling outside air from a large hole in the floor (old chimney) behind a false wall in the broom closet where the "duct" was ran. That explains the excessive dust (7 HEPA filters running 24/7 to help control it) and the inability to cool the house.

    I wanted the new air handler in the broom closet and not back in the attic to increase efficiency. The contractor sealed the closet, the hole in the floor and put the air handler in the closet. The hallway return duct (14x14) was eliminated and the living room return grill (14x23) was opened up to accommodate a 18x30 filter.

    The filter is in the 18x30 intake in the living room the hole runs directly into the closet that houses the air handler. Under teh closet door I have added a rubber sweep to "seal" the bottom of the door from getting unfiltered air into the unit. The problem however is that the unit seems to struggle with the 18x30 filter. When I close the closet door you can hear the fan motor sound as if it speeds up some when it is pulling through the filter.

    I can't get a 22x22 filter in (filter rack size on the bottom of the unit) because the door opening is only 20". I removed the door and jamb to get the air handler into the closet and have everything back together now. I did however manage to get a pleated filter into the filter rack with a bit of "help". I removed the 18x30 filter and it seems to not struggle as bad.

    I'm guessing that it wouldn't hurt to add another return grill & 18x30 filter in the master bedroom (other side of the broom closet) ....

    Or could I simply put a piece of 22x22 gutter guard material in the filter rack and simply buy 22x22+ filter media for the bottom of the air handler?

    I am very limited on space so not sure what to do. The contractor feels that the single 18x30 intake in the living room should be ok....

    It may be worth mentioning the fan speed is set on Med-High (T-4) tap.



    I will provide pictures as soon as I get back home.

    thanks for any suggestions.

  2. #2
    Join Date
    Nov 2008
    Location
    Chapel Hill, NC
    Posts
    1,070
    Measure the external static pressure. There is a specification for this on your furnace. 18x30 may be OK, depending on the filter (don't use 3M Fitrete) and ductwork but you will probably benefit from a second return.

  3. #3
    Join Date
    Dec 2007
    Location
    houston, texas
    Posts
    3,787
    Put the return in the system. Your on the right track. Manf now a days like to shoot for 200 sq" per ton if possible.
    I'm not tolerating Political Correctness anymore, from now on it's tell it like it is.

    Veto Pro Pak - The best tool bag you'll ever own






  4. #4
    Join Date
    Apr 2010
    Posts
    62
    Picture 1 shows the old intake size:
    http://i44.tinypic.com/c546d.jpg

    Picture 2 shows the closet ceiling after the hole was patched and prior to sealing with caulking.
    http://i43.tinypic.com/2e6hs9w.jpg

    Picture 3 shows the chimney we didn't know was there. (Behind the "wall" of plywood that was removed.
    http://i43.tinypic.com/5p4pxl.jpg

    Picture 4: back of the old intake
    http://i42.tinypic.com/9bgjlt.jpg

    Picture 5 - 7 New return intake grill (18x30)
    http://i43.tinypic.com/2a94axy.jpg
    http://i39.tinypic.com/2n9ffut.jpg
    http://i43.tinypic.com/mn27bo.jpg

    Picture 8-11 Shows the door back on, trim on and air handler installed in the closet. Door width is 20". Last pic shows the air filter (22x22) @ the bottom of the unit.
    http://i42.tinypic.com/xf8fb4.jpg
    http://i39.tinypic.com/2wf349v.jpg
    http://i43.tinypic.com/20fc1fo.jpg
    http://i42.tinypic.com/ykk6o.jpg




    .....Edited for picture size

  5. #5
    Join Date
    Apr 2010
    Posts
    62
    Picture 12 - Looking up
    http://i39.tinypic.com/25tw9jd.jpg

  6. #6
    Join Date
    Sep 2005
    Location
    Atlanta GA area
    Posts
    21,404
    If it were me, I would have mounted the AH unit about a foot higher in the closet, and added the second return in the MB... and place air filters in the filter grills at both locations (then remove the filter at the bottom of the AH). It is hard to 'over return' a system. Think about this: If the system cannot suck enough air, how can it blow enough air???
    GA-HVAC-Tech

    Quality work at a fair price with excellent customer service!

    Romans Ch's 5-6-7-8

    2 Chronicles 7:14

  7. #7
    Join Date
    Apr 2010
    Posts
    62
    With the 22x22 filter I can't get it out of the unit without pulling it down and folding up the filter; the door opening is only 20".


    When I put the 18x30 filter in the return and add the baffle on the bottom of the door the unit seems to "pull" / struggle almost.

    Why would that be with the 18x30 actually having more filter area VS the 22x22?



    If I were to have the contractor open an additional 18x30 in the MBR, would the noise be too much?
    What about adding a filter on the closet door?

    Thanks for the replies.

  8. #8
    Join Date
    Dec 2004
    Location
    Oldsmar,FL
    Posts
    32
    Hi from FSN.

    Looks like there's an air handler behind your filter!

    Rework the door jam and drain line so you can replace the filter and add another grill or 2 to the closet. I can't tell by the picture but maybe just cut an angled slot out of the jam to slide the filter through.

    You need to slow down the air through the 18x30 filter grill.

  9. #9
    Join Date
    Apr 2010
    Posts
    62
    Quote Originally Posted by bsharp View Post
    Hi from FSN.

    Looks like there's an air handler behind your filter!

    Rework the door jam and drain line so you can replace the filter and add another grill or 2 to the closet. I can't tell by the picture but maybe just cut an angled slot out of the jam to slide the filter through.

    You need to slow down the air through the 18x30 filter grill.

    Fellow FSN'er.

    If I reworked the door jamb it would require me to cut a 1" notch out of the jamb and door to allow the filter to exit. The only other alternative is to order another custom-cut door that's nearly $300. Home Depot screwed up the size , the jamb opening is 23 1/4w, they sent a 20" door.

    A 1" notch in the door /trim would look weird.

  10. #10
    Join Date
    Dec 2004
    Location
    Oldsmar,FL
    Posts
    32
    Quote Originally Posted by Mighty Hd View Post
    Fellow FSN'er.

    If I reworked the door jamb it would require me to cut a 1" notch out of the jamb and door to allow the filter to exit. The only other alternative is to order another custom-cut door that's nearly $300. Home Depot screwed up the size , the jamb opening is 23 1/4w, they sent a 20" door.

    A 1" notch in the door /trim would look weird.

    I see that, the pic made it look like an angled cut behind the molding might have worked.

    I am worried about noise in the bedroom but you need more return air so the bedroom and another in the door look like the only options.

    You may have to get that larger door just for filter access unless someone has a better idea.

  11. #11
    Join Date
    Apr 2010
    Posts
    62
    Quote Originally Posted by bsharp View Post
    I see that, the pic made it look like an angled cut behind the molding might have worked.

    I am worried about noise in the bedroom but you need more return air so the bedroom and another in the door look like the only options.

    You may have to get that larger door just for filter access unless someone has a better idea.
    If I were to have another 18X30 return cut in the bedroom, that would allow sound from the living room & AH closet into the MBR.

  12. #12
    Join Date
    Sep 2005
    Location
    Atlanta GA area
    Posts
    21,404
    Quote Originally Posted by Mighty Hd View Post
    If I were to have another 18X30 return cut in the bedroom, that would allow sound from the living room & AH closet into the MBR.
    Or sounds from the bedroom into the living room...

    Might want to do the hall return in the door...
    GA-HVAC-Tech

    Quality work at a fair price with excellent customer service!

    Romans Ch's 5-6-7-8

    2 Chronicles 7:14

  13. #13
    Join Date
    Apr 2010
    Posts
    62
    This was suggested to me ...

    Using replaceable filter media sized 22x22 in a filter frame under the AH. Have a frame made that would fit through the door and telescope to 22x22 +/- and secure that size with machine screws....



    using something like this:


    Last edited by Robb M.; 07-08-2013 at 09:36 AM. Reason: removed hacked link: [img]http://hbairfilters.com/shop/images/uploads/MERV_9_PADS_AND_ONE_IN_FRAME.jpg[/img]

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