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  1. #1
    Join Date
    Nov 2012
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    18

    Replacing 24-year-old Noisy Furnace--Looking for Advice

    Hi,

    We are replacing a 24-year-old furnace in a condominium that has a faulty valve. It will cost around $$$ to replace the valve and that seems unwise in a furnace this old. It is an upflow configured furnace (Train BLUI62F960B2 with a Bryant coil). It is in a mechanical closet with a water heater, and a ductless return which is facing the main living space. It is very noisy, and we are told the system is oversized. Our primary concern is noise and cost; we are trying to sell the unit but could be here awhile in this market.

    I am told that an 80% efficiency unit makes the most sense due to venting issues. We are on the 2nd and 3rd floor of a three story building, new venting required for higher efficiency units seems impractical. Our square footage is around 2000, and we have some additional air volume with sloped cathedral ceilings.

    One estimate I received was for a Coleman modulating 80 furnace with new coil and condenser. I liked this bid, but my concerns are two fold: the contractor specified an identical 5-ton size, while other contractors told us we didn't need such a large unit. Second, if sized correctly, I'm concerned that it will run constantly. This would make the noise factor critical. (It's one thing for a manufacturer to claim it is quiet and another for it to truly be quiet.)

    A second option I am considering, but haven't priced, is a Rheem combination tankless heater and furnace. This would replace the equally old water heater, and by removing the water heater from this closet might allow us to place the return in a hallway at right angle to the living space. This would involve some duct work/drywall removal.


    1) How do I find out the correct size--is a manual J calc necessary, or can i trust someone's judgment?

    2) Do you think it is worth the extra cost to relocate the return (i.e. go with a tankless Rheem system) or should I just go with a modulating furnace, such as the Coleman? (The Rheem would be a two stage, I believe.)

    3) Is there a way to find out the actual dBs of the blowers?

    Any input would be greatly appreciated, as well as any other suggestions, or alternative equipment to consider.
    Last edited by jpsmith1cm; 11-12-2012 at 04:51 PM. Reason: Pricing

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,773

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,316
    Must be one huge condo to need that monster furnace and 5 ton drive. 1st step is accurate load calc. Odds are it doesn't need that big unit. Moving less air will quiet things down. Ducted return will help or have them build a box under it and insulate it. A picture of the install would help us understand how it is down now. Ductless return and a water heater in the same closet sounds dangerous now that I think of it.

  4. #4
    Join Date
    Nov 2012
    Posts
    18
    Quote Originally Posted by BaldLoonie View Post
    Must be one huge condo to need that monster furnace and 5 ton drive. 1st step is accurate load calc. Odds are it doesn't need that big unit. Moving less air will quiet things down. Ducted return will help or have them build a box under it and insulate it. A picture of the install would help us understand how it is down now. Ductless return and a water heater in the same closet sounds dangerous now that I think of it.
    I don't know why it is upside down, but that's the furnace, return register and water heater visible in background (white). I tried posting a flipped version of it and it is still upside down.

    Name:  furnace.JPG
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Size:  120.9 KB

  5. #5
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
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    2,739
    What size is the A/C. You said 5 ton, but I think you might have been talking about the blower.

    I agree with B.L. The new furnaces are much shorter which will allow for a box under.

    If there is room, on the side or under the furnace, for a hi-efficiency filter, they do a great job of quieting the noise.

    A commercial grade, properly sized RA grille would also help.

  6. #6
    Join Date
    Nov 2012
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    18
    Quote Originally Posted by George2 View Post
    What size is the A/C. You said 5 ton, but I think you might have been talking about the blower.

    I agree with B.L. The new furnaces are much shorter which will allow for a box under.

    If there is room, on the side or under the furnace, for a hi-efficiency filter, they do a great job of quieting the noise.

    A commercial grade, properly sized RA grille would also help.


    The blower is definitely 5 tons. The furnace model number is above, I can't find anything on it due to the age. It is rated to 162,000 BTU/hr, if that tells you anything about the size (I believe it is five tons). It is definitely oversized, no question about that. On for awhile then off for an equal period. The question is, what size should it be? I talked to one contractor about a manual J calc, but there is a significant cost involved. Are there other estimating methods?

    So, putting it on a box would mean creating a right angle in the return air, if my understanding of what you are suggesting correct. The headroom in the closet is 7 feet, floor to ceiling.

    Would a larger grill make a difference, we might be able to increase the width somewhat (~6") and the height--or are we better matching the grill size to the return size of the unit? Thanks.

  7. #7
    Join Date
    Aug 2012
    Location
    North Dakota
    Posts
    518
    the cost of not doing a man j will be far greater (any contractor that doesnt do man. j is just guessing) so what else are they going to guess on quality ,safety, ect. ect.!!!!do your homework get sevral bids and refrences you may even ask to see some recent installs of theirs

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,330
    The outdoor units model number would tell us what size A/C you have.

    How big is your condo.

    A load calc would tell what size heat and A/C you need.

    A properly furnace and A/C moving less air would probably not be as loud as your current one is.
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  9. #9
    Join Date
    Nov 2012
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    18
    Quote Originally Posted by beenthere View Post
    The outdoor units model number would tell us what size A/C you have.

    How big is your condo.
    2000 Sq. ft. with high ceilings. Everything is 5 ton. (I got a bid from a contractor, which was lazy, and he specified all 5-ton equipment.) The outdoor condenser unit is a Lennox Mod# HS29-060-1P.

    Name:  Lennox med.JPG
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    A load calc would tell what size heat and A/C you need.

    A properly furnace and A/C moving less air would probably not be as loud as your current one is.

    One concern is would the ductwork that I have be sized for the 5-ton blower, and would going smaller create any problems?




    (The bid I got: No prices

    FURNACE M# CP8C120C20MP12C, 80%, 120K, 5 TON
    FF #170 GRILL W/ FILTER
    HONEYWELL PRO 4000
    EXPANSION VALVE 1TVM09-06, 5 TON R-410A
    COIL M# FC60C3XN1 (5 TON) UPFLOW COIL
    CONDENSER UNIT M# TCGD60S41S2 (5 TON) 13 SEER

    )

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,330
    Good chance you only need around a 80,000 BTU 80%. 5 tons still sounds big.

    Your duct work is probably under sized for 5 tons. So a smaller unit would move air better and quieter.
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  11. #11
    Join Date
    Nov 2012
    Posts
    18
    Thanks for the help. How many tons would that (80K) be? (Current BTUS on furnace is 162,000, it's 24 years old.)

    The reason I didn't go with the proposal I received is two contractors told me I could go quite a bit smaller, one told me I could probably go about 3.5 tons. (Unfortunately, he never got me a bid.)

  12. #12
    Join Date
    Aug 2012
    Location
    North Dakota
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    518
    probably and should work??

  13. #13
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,739
    If that is the only return that you have, then it is way too small for the 2,000 cfm needed!

    I doubt the supply can handle 2,000 cfm. The 5 ton (now) is not working to it's full ability.

    The size of the new equipment will be based on how your condo is exposed to the weather/sun. A manual J would be the most accurate, but it's hard to get one of those.

    The new furnace and coil will fit in the closet on a box. No problem. Your new filter should be at least 20"x25", which should be fine on the new (smaller) A/C unit.

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