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  1. #1
    Join Date
    Jan 2011
    Location
    Albuquerque, NM
    Posts
    9

    Upstairs is to cold in winter and to hot in summer

    Greetings,

    I wanted to get an opinion on how to resolve the issues we have.

    Our home is a two story 2600 sq ft home in Albuquerque, NM which isn't high humidity or extreme temperatures either way.

    Our upstairs bedroom (above the north facing 3 car garage with non insulted doors but insulated walls) is cold in the winter and hot in the summer. The air handler is a Rheem Criterion II 5 ton downdraft unit mounted upstairs. The Return in the attic in insulated 16" flex into the side of a box in which air enters in at 90 degrees. the grill on the box is 20x20 and is at the top of the stairs in the ceiling. Home has no 2nd story vaults. The master bedroom has 2 vents with the attached bathroom/closet combo with one vent, about 450sq ft total. Downstairs gets hot fast in the winter (and we have a nice AFUE-rated gas fireplace that can put out 24k btu/h) and in the summer will freeze into the mid 60s before upstairs gets in the mid 70s.

    The filters are inside the unit, which i believe the installer did a bang up job of making the filters worthless since the attached ducting for the return has a ledge that causes a 1" gap in all but the lip where the ducting attaches. The Filters are mounted in a V shape on the return entrance and is 2 16" filters.

    I called an A/C contractor that I already know, and he told me over the phone it was probably poor duct design and the home should have had 2 smaller units installed with one upstairs and one downstairs. I agree, but that sounds like reconstructive surgery. When he came out, he stated the same results and didnt think another return (like I thought) would help. He took no measurements and in fact never had the unit turn on - just asked if the vents near the curtains would make the curtains move when air was blowing out. Also, a worthy note it that when the unit turns on there is a howl in the return vent, which disappears with the blower door off.

    While I don't doubt that the ducting design may be at fault, my own tests of running the unit for a few minutes without the blower door on increased air flow and comfort quite a bit. I know that's not a good way to do this - that's why after that I called a pro. His answer was a small mini-split for that bedroom. I'm not sure I want to pay for that and the additional maint. cost of having 2 units.

    Are there other options I should think about, or what else can I do when selecting my next HVAC pro to give me more input.

    Thanks

    Joel

  2. #2
    Join Date
    Feb 2010
    Location
    Cal
    Posts
    1,596
    You can start by doubling up on the return duct/grill and correcting the filter situation. 5 ton/2000 cfm thru a 16" (wireflex duct?)sounds very restrictive. good for about 750 cfm.

    The right contractor with the right instruments can narrow down where the biggest problem is. You have to find him.

  3. #3
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,595
    You found the problem by yourself. Your return (duct and grille) is too small.

    Your (A/C) buddy must be ignorant. You noticed the differance (in airflow) when you took off the blower door.

    However, if they didn't know how to size the return side, the supply side could be restrictive also.

    Find someone that knows (and cares) to fix the lousy work. It should be fairly simple.

  4. #4
    Join Date
    Jan 2010
    Location
    Athens GA
    Posts
    1,234
    If you have discribed the appointment with the contractor accurately then my advice is to cross his phone number in the phone book out in ink.Then take his card and rip it into as many pieces as you can,then take classes if you need to ,to forget him totally.
    Otherwise he sounds wonderful.
    Here I am 2000 miles away and I can tell that your ductwork,both supply and return is terrible.This condition is costing you hundreds and hundreds of dollars every year and it is shortening the life of your equipment.
    Call and call until you get at least 3 contractors that will do a Manuel J AND,AND a Manuel D.
    If you don't do this you are just throwing money AND comfrort out the window.
    There just isn't any other way,everything else is just guessing with your money and your comfort.

  5. #5
    Join Date
    Nov 2008
    Location
    Chapel Hill, NC
    Posts
    1,070
    Can you check the dampers where the branchlines come off the main trunk. Sounds like you aren't getting enough air distribution (hot air in the winter, cold air in the summer) upstairs. This could be due to inadequate air return from upstairs or inadequate air delivery upstairs. Is the air flow from the upstairs bedroom vents as high as that from the downstairs vents, or is is weak? In any event, I'd make sure the dampers to the upstairs branch lines are fully open and you may want to close down the downstairs branchline dampers some. And before people start howling, yes, this will increase static pressure and work on the furnace some but if it improves the temperature evenness, it tells you what the problem is.

  6. #6
    Join Date
    Jun 2009
    Location
    Albuquerque NM
    Posts
    2,483
    Joel - I'm in ABQ (Taylor Ranch area). I can't say I have an immediate answer to your problem, but if you send an email to the address in my profile, we can trade tips on contractors and such. There are a lot of hacks around here, and even more of what I call "semi-pros". Most of the homes around here that I've seen have about half the needed return size.

  7. #7
    Join Date
    Jan 2011
    Location
    Albuquerque, NM
    Posts
    9
    I don't plan to call him again, but this all does seem to confirm what I think is the bulk of the problem - the return air grill.

    I do not believe there are dampers in my system aside from what is on the registers. That seems to be the norm in my area (no dampers in the system that is).

    I also think the best way to resolve the filtering issue is to replace the grills with something that will hold a filter.

    Any good ways to tell who is going to do Manual D & J and take pressure readings etc without saying it? I don't want a contractor to do this ONLY because I asked them to, but rather one that wanted to - i.e. some one who gives a rats rear. I'm disappointed in the ACCA website as the contractor that installed my system in listed there and based my understanding and everyone here so far, the return is wrong.

    Joel

  8. #8
    Join Date
    Jan 2008
    Posts
    1,955
    Your problem is very common to most 2 story homes. Manual or automatic zoning is the best solution. A nominal change in return air grills most likely won't solve the problem.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  9. #9
    Join Date
    Jan 2011
    Location
    Albuquerque, NM
    Posts
    9
    Quote Originally Posted by 2old2rock View Post
    Your problem is very common to most 2 story homes. Manual or automatic zoning is the best solution. A nominal change in return air grills most likely won't solve the problem.
    Is that a major renovation? I've thought of that, but I don't understand how that gets done on an existing system with ducts between the floors?

    Joel

  10. #10
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,595
    This is the formula to sizing a return air grille: 2 cfm per square inch.

    Your grille is 20x20 = 400x2 = 800 cfm; good for 2 tons of A/C.

    Is it possible to add another one that's the same size?

    What size is your filter at the furnace?

  11. #11
    Join Date
    Jan 2011
    Location
    Albuquerque, NM
    Posts
    9
    Quote Originally Posted by George2 View Post
    This is the formula to sizing a return air grille: 2 cfm per square inch.

    Your grille is 20x20 = 400x2 = 800 cfm; good for 2 tons of A/C.

    Is it possible to add another one that's the same size?

    What size is your filter at the furnace?
    It's possible to add several returns, ducts in the attic and I've got enough room in the ceiling.

    In the furnace there are two 16x20 filters inside shaped like a V on the top of the unit where the air blows down through. The filtering is worthless since there is gaps inside and even getting the filter in there requires crushing the filter down and then trying to expand it once it's past a lip. Then you have to bring the filter back down an inch into the lip to set on the rack. I'd like to use filters at the return(s) if I can.

    Joel

  12. #12
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,595
    Quote Originally Posted by Jabq View Post
    It's possible to add several returns, ducts in the attic and I've got enough room in the ceiling.

    In the furnace there are two 16x20 filters inside shaped like a V on the top of the unit where the air blows down through. The filtering is worthless since there is gaps inside and even getting the filter in there requires crushing the filter down and then trying to expand it once it's past a lip. Then you have to bring the filter back down an inch into the lip to set on the rack. I'd like to use filters at the return(s) if I can.

    Joel
    The filter grille sizes will depend on the size of your A/C. You can size it to the drive of the furnace or air handler which will assure a quieter system.

    I tend to over size the filters to compensate for the dirt build up (restriction).

    You'll need 2 more 20x20 (filter) grilles. Replace the existing flat grille with a filter grille.

  13. #13
    Join Date
    Dec 2007
    Location
    Cedar Grove, Wi-Sheboygan
    Posts
    1,582
    Why not do your own heat load using the software here on this site at the top of the page, if you can use a measuring tape you can do your own heat load and save a few bucks. Call your state or local power Co. Most will have some sort of program where they will come and do a home analysis for free or for a modest fee based on your income and that usually includes a blower door test in most if not all cases. it's worth your time to at least give them a call and see what they offer or can at least refer someone whose reliable/competent in doing good work.

    I'd see if you can't get up in your attic space and enlarge your returns and add at least 2 or 3 more returns thru out your home. At minimum you should have at least 6" supplies running to all your rooms or in some cases 7" or 8" supplies depending on room size of course, where a 6" supply is generally good for approximately 110 cfm's. so if your somewhat handy and knowledgable you could for the interim fix or improve what you have until you find Mr. right to give you a properly functioning equipment to where it's not costing you more than it should to give you the proper comfort thru out the h/c seasons year round.

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