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  1. #1

    Thumbs up Consumer with an air intake question on a 4 ton heat pump

    Good morning,

    I appreciate you guys and the help offered. I want to be a well informed consumer. ..

    I currently have 8 year old Goodman 10 seer 4 ton split unit. I want to swap this out with a newer system because the old one has coil leaks. This is my downstairs system. The upstairs is separate and will not be replaced.

    Three of my potential 4 install companies reps have raised the issue of my intake. The current intake is 16" flex duct about 7 feet long and has a 90 degree bend. The intake of the duct is ovaled to 14"x16" and sits in the floor of a chamber under my stairs that is about 18" deep, 28" wide and about 36" tall. There is a grill with tight levours for the intake on the wall that takes a 24" by 30" filter. I use a Filtrette filter that has cardboard reinforcing so the actual surface area of the filter is less than 24x30 although it is pleated.

    Contractor 1 wants to use the current system, just swap out the levour grill to one that has bigger slats.

    Contractor 2 wants to increase the intake to 18" and expand the chamber under my stairs to accommodate a 30" x 30" filter.

    Contractor 3 says I need more intake. He wants to add a separate second intake somewhere in another area. He states expanding the current intake to 30x30 will do the trick although it isnt to TVA specs and wont qualify for TVA financing.

    Airflow though the home I dont think is an issue as there are at least 1" gaps under all doors with hardwood floors throughout. Partially open doors will slam shut sometimes when the system starts.

    Thanks for your comments. . .

  2. #2
    Join Date
    Mar 2007
    Location
    Myrtle Beach, SC
    Posts
    2,919
    Quote Originally Posted by au_prospector View Post
    Good morning,

    I appreciate you guys and the help offered. I want to be a well informed consumer. ..

    I currently have 8 year old Goodman 10 seer 4 ton split unit. I want to swap this out with a newer system because the old one has coil leaks. This is my downstairs system. The upstairs is separate and will not be replaced. Did anyone do a Manual J load calculation to see if 4-ton is the right size?

    Three of my potential 4 install companies reps have raised the issue of my intake. The current intake is 16" flex duct about 7 feet long and has a 90 degree bend. The intake of the duct is ovaled to 14"x16" and sits in the floor of a chamber under my stairs that is about 18" deep, 28" wide and about 36" tall. There is a grill with tight levours for the intake on the wall that takes a 24" by 30" filter. I use a Filtrette filter that has cardboard reinforcing so the actual surface area of the filter is less than 24x30 although it is pleated. I would not use a Filtrete filter, it is very restrictive.

    Contractor 1 wants to use the current system, just swap out the levour grill to one that has bigger slats.

    Contractor 2 wants to increase the intake to 18" and expand the chamber under my stairs to accommodate a 30" x 30" filter.

    Contractor 3 says I need more intake. He wants to add a separate second intake somewhere in another area. He states expanding the current intake to 30x30 will do the trick although it isnt to TVA specs and wont qualify for TVA financing.

    Airflow though the home I dont think is an issue as there are at least 1" gaps under all doors with hardwood floors throughout. Partially open doors will slam shut sometimes when the system starts. Sounds like your doors need more undercut or transfer grilles. How did you determine your air flow is OK? What did you use to measure it with? Sounds like a lot of guessing

    Thanks for your comments. . .
    I think you need to address your return. Sounds like #3 is closests, but I would want measurements.
    Remember, Air Conditioning begins with AIR.

  3. #3
    Join Date
    Oct 2009
    Location
    Phoenix
    Posts
    155
    The first thing I would do is toss the filtrete filter in the trash. 1" filters are too restrictive because they have insufficient media, unless they're so "open" that they filter nothing.

    The second thing I would do is consider adding a second 16" duct to a second 24x30 grille.

    Too much is just right when it comes to return air.

    If you want a good filter, consider a 4-5" thick media filter at the air handler or the 4" thick Honeywell FC40 series filters if you have "filter grilles". You can likely swap them once a year without experiencing a significant pressure drop.

    The restriction is important, because starving the unit of airflow will reduce it's performance and effectiveness, and cost you money in your utility bills.

  4. #4
    Okay I get that you guys dont like the filters I use.

    I am not sure and a bit apprehensive about adding another return. I am afraid of what it would look like, the returns I have is ugly as it is. . .

    I can go with those honeywells you are talking about. I did a quick search and didnt find them in anything bigger than 24x30. Do they make them bigger? If I use this instead of the filtrete, do I still need more or bigger returns?

    Kevin, nobody has whipped out a calculator to determine the load calculation you speak of. Most anyone did was ask about the current system, ask about square footage both upstairs and down and counted/measured the size of registers in the floor.

    Your right, I am guessing about the return flow in the home. Intake grill is centrally located and all doors are open 95% of time so Im not too worried about the flow unless you give me something else to think about.

    The second thing I would do is consider adding a second 16" duct to a second 24x30 grille. RZYZZY this is what the one contractor wanted to do, though not quite that big. Sounds like some major cutting and reframing work here that wont be pleasing to my wife's eye.

  5. #5
    Join Date
    Sep 2007
    Location
    Tucson AZ
    Posts
    19
    #3 has the best approach of the 3 contractors you've described. He is right on that a 30"x30" will be somewhat under sized. If it were me I'd let him install the larger duct and return. With more return area you will not hear has much air noise because the velocity through each return grill will be lower.

  6. #6
    Join Date
    Oct 2009
    Location
    Phoenix
    Posts
    155
    Quote Originally Posted by au_prospector View Post
    Okay I get that you guys dont like the filters I use.

    I am not sure and a bit apprehensive about adding another return. I am afraid of what it would look like, the returns I have is ugly as it is. . .

    I can go with those honeywells you are talking about. I did a quick search and didnt find them in anything bigger than 24x30. Do they make them bigger? If I use this instead of the filtrete, do I still need more or bigger returns?

    Kevin, nobody has whipped out a calculator to determine the load calculation you speak of. Most anyone did was ask about the current system, ask about square footage both upstairs and down and counted/measured the size of registers in the floor.

    Your right, I am guessing about the return flow in the home. Intake grill is centrally located and all doors are open 95% of time so Im not too worried about the flow unless you give me something else to think about.

    The second thing I would do is consider adding a second 16" duct to a second 24x30 grille. RZYZZY this is what the one contractor wanted to do, though not quite that big. Sounds like some major cutting and reframing work here that wont be pleasing to my wife's eye.
    Return air "cans" are made of thin sheet-metal - They don't require "major" framing to hold them in place - The builder of my home attached mine to a single stud - all you're supporting is the can, the weight of the ductwork, and the filter-grille. It's possible to add bracing from the attic side without disturbing the drywall if you feel you need it.

    I currently have two 20x30 filter grilles in the ceiling, with a pair of the Honeywell filters attached to two (short) 16" flex ducts - hooked up to a 4 ton air handler. When the handler kicks into "stage two", you can still hear the filters "creak" a little bit - I personally wouldn't be comfortable with going any smaller, the cost to add return capacity is going to be mostly labor, and will be similar whether you put in a big grille or a small one.

    I suggested using the same size for return #2, simply for convenience - no need to remember two different size filters when you order replacements.

    A thick "media filter" at the air handler would probably be the best solution - If I had to rebuild my system - that's probably what I would do. If you did that, you could toss your current filter-grille out, and have more freedom to pick a smaller 2nd return. Bigger does = quieter though if everything else is the same...

    As for just upgrading to the better filter and hoping for the best - it would certainly be better than what you have, but why not fix it right and forget about it?

  7. #7
    Join Date
    Apr 2010
    Location
    Central New Jersey
    Posts
    34
    I agree. #3 has best plans. Adding another return somewhere on the opposite end of the house will provide for better balancing and reduced noise.

  8. #8
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    Since you're somewhat shy and therefore haven't given us any clues as to where you reside, I'll make broad statements.

    1. Accept no company that doesn't voluntarily do a full, room-by-room Manual 'J' load calculation.
    2. Accept no company that doesn't do a Manual 'D' duct calculation.
    3. If a Manual 'J' has not been done, it's impossible to determine the size of the equipment even by nominal size, let alone by actual size. Nominal size is the rating on the equipment, which is for 95*F and 70% Sensible Heat Load, 30% Latent heat load.

    If the conditions in your area of the world are substantially different than those criteria, then it's most likely the equipment will be inappropriately sized, absent doing it right. But on the other hand, if you like to gamble with thousands of dollars on a single bet, you can skip the load analysis and just guess, like the installing company will be doing. These are my statements. Shop accordingly.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  9. #9
    Join Date
    Jan 2005
    Location
    Emerald Coast
    Posts
    934
    Contractor #3 is on the right track from what you describe.

    ...
    Do not attempt vast projects with
    half vast experience and ideas.
    ...

  10. #10
    Join Date
    Mar 2007
    Location
    Myrtle Beach, SC
    Posts
    2,919
    Quote Originally Posted by au_prospector View Post
    Okay I get that you guys dont like the filters I use.

    I am not sure and a bit apprehensive about adding another return. I am afraid of what it would look like, the returns I have is ugly as it is. . .

    I can go with those honeywells you are talking about. I did a quick search and didnt find them in anything bigger than 24x30. Do they make them bigger? If I use this instead of the filtrete, do I still need more or bigger returns?

    Kevin, nobody has whipped out a calculator to determine the load calculation you speak of. Most anyone did was ask about the current system, ask about square footage both upstairs and down and counted/measured the size of registers in the floor.

    Your right, I am guessing about the return flow in the home. Intake grill is centrally located and all doors are open 95% of time so Im not too worried about the flow unless you give me something else to think about.

    The second thing I would do is consider adding a second 16" duct to a second 24x30 grille. RZYZZY this is what the one contractor wanted to do, though not quite that big. Sounds like some major cutting and reframing work here that wont be pleasing to my wife's eye.
    Send me an email. I will send more information than I can retype in this thread by return email. My email address is in my profile. You should put yours in your profile too.

    Kevin
    Remember, Air Conditioning begins with AIR.

  11. #11
    Okay okay, I will come out Skippedover. I live in North Georgia where 95 is pretty normal and we exceeded that maybe a dozen times so far this summer.

    I purchased our home 3 years ago. It was built in 2002.
    2700 square feet on the lower level
    -9 foot ceilings
    -900 square foot master area separated by a 8 foot hall from the rest of the lower.
    -600 square feet has 18 foot ceilings with a balcony on top that connects to the second level
    -many windows, most of which are 30"x70" mostly on the west side

    800 square foot second level
    -serviced by a 2.5 ton unit that I will keep.
    -balcony has two ducts to the 2.5 ton and is open to the lower level below
    -balcony and 3 bedrooms

    If I can get ahold of the formula, I could calculate this myself? (the J formula and the D formula)

    I think one guy did the D formula as he was counting and measuring the size of my ducts throughout the home. If he did a J formula, he didnt tell me.

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