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  1. #1

    HVAC Replacement Options

    Hi HVACers,
    I've heard a lot of great things about this forum, and would appreciate some advice.

    I have a 2 story house (1900 sq ft) with a 95% finished basement (1000 sq ft) that does not have ductwork and vents for AC / Heat. I have an 18 year old HVAC unit in the basement that I've been told I should replace because it is so old. I've also been told by neighbors that these original units are not powerful enough for the size of the houses.

    The unit does a decent job heating and cooling the main floor, but a horrible job on the 2nd floor; usually a 10-15 degree difference, even with all the main floor vents shut. This means in my GA summers, it will be 75 downstairs and 85-90 upstairs, even with all the 1st floor doors vented.

    I'd like to budget for a replacement (I plan to be in the house at least 5 more years), but I don't know if I should:
    1) Replace the basement unit with a larger unit.
    2) Add an additional unit in the attic for the 2nd floor.
    3) Look into a zoning system.
    4) Any other ideas?

    I hope to have a few HVAC companies give me estimates, but I want to have a better idea of what are the questions to ask, and what I should look for.

    Here are the details I could make out of my current system:
    1) Outside heat pump: GSH130361AD
    2) Furnace: Carrier 58PAV090-14

    Thanks for any advice you can provide!

  2. #2
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    7,455
    The best option is to put install a unit for the upstairs.

  3. #3
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,739
    On really hot or cold days does the equipment run continuously, or does it cycle on and off?
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  4. #4
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    7,455
    Have a manual j performed so you get the correct size unit/s

  5. #5
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,372
    Quote Originally Posted by jtrammel View Post
    The best option is to put install a unit for the upstairs.
    +1. You could do straight A/C with a small amount of electric heat for upstairs.
    Installing a heat pump may be worthwhile for upstairs depending on how much you actually run the heat up there.
    I'd leave the downstairs system as-is until it goes out. Modify the ductwork so it only serves the downstairs.

  6. #6
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,372
    Quote Originally Posted by jtrammel View Post
    Have a manual j performed so you get the correct size unit/s
    Odds are the 90,000BTU furnace is WAY overkill for an area that rarely dips below freezing.

  7. #7
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,739
    A unit that is grossly oversized will satisfy the downstairs thermostat before the duct upstairs warms or cools enough to deliver ANY btu upstairs.

    Get the house figured out. Putin the smallest equipment you can convince anyone to install, your imbalance issue will improveSIGNIFICANTLY. You may need to seal some leaks in the attic and add some cellulose to completely solve things.

    Starts with a comprehensive assessment including blower door test.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  8. #8
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,323
    Quote Originally Posted by Rewdog View Post
    Hi HVACers,
    I've heard a lot of great things about this forum, and would appreciate some advice.

    I've also been told by neighbors that these original units are not powerful enough for the size of the houses.

    Here are the details I could make out of my current system:
    1) Outside heat pump: GSH130361AD
    2) Furnace: Carrier 58PAV090-14

    Thanks for any advice you can provide!
    Are your neighbors really experienced or even familar with ACCA Manuals J, D, S & T ?
    House + HVAC Equipment + Air Distribution = 1 INTEGRATED SYSTEM

    ... If blood does not flow to your foot, you are not going to be feeling very well.
    .. I am not going to listen to any neighbors providing Internal Medicine advice.

    _ U need a good HVAC Doctor ... to diagnose your residential ailments.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  9. #9
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,323
    Quote Originally Posted by 54regcab View Post
    +1. You could do straight A/C with a small amount of electric heat for upstairs.
    I would NEVER provide advice that is against the state law!
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  10. #10
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,372
    Quote Originally Posted by dan sw fl View Post
    I would NEVER provide advice that is against the state law!
    My bad, I didn't realize it wasn't allowed in GA. Entire homes are often heated with strip in Oklahoma which ironically is colder than GA The only time I'm OK with heat strips as a primary heat source is for where it's rarely ran.

  11. #11
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by Rewdog View Post
    I have a 2 story house (1900 sq ft) with a 95% finished basement (1000 sq ft) that does not have ductwork and vents for AC / Heat. I have an 18 year old HVAC unit in the basement that I've been told I should replace because it is so old. I've also been told by neighbors that these original units are not powerful enough for the size of the houses.
    I'd like to budget for a replacement (I plan to be in the house at least 5 more years), but I don't know if I should:
    I hope to have a few HVAC companies give me estimates, but I want to have a better idea of what are the questions to ask, and what I should look for.

    Here are the details I could make out of my current system:
    1) Outside heat pump: GSH130361AD
    2) Furnace: Carrier 58PAV090-14

    Thanks for any advice you can provide!
    3 tons should be plenty large for that home. Design temrpatures in GA are a lot lower than most people think. "hot-lanta" desing tmperature is actually cooler than were I am in SE Iowa.

    WHen I hear "neighbor say they are undersized". That tells me that it's probaly sized perfectly, but ductwork is designed and installed poorly and liekly undersized for hte upstairs (very common in newer construction) and any 2 story hoem is best served by zoning. On top of that it probably lacks adequate insulation in the attic, poor attic venting and has a lot of air leaks bringing in hot humid air upstairs. All common problems.

    As others mentioned, adding a unit to serve just the upstairs might be your best solution for comfort and performance and leave the existing system.


    That furnace is massively oversized for you climate. You probably barely need even 60k BTU's even with a fully finished basement.

    You probably need something like 2 tons upstairs (2 stage is best if yu can afford it) and just install a heat pump with electric auxillary only and 1.5 tons for the downstairs and basement with a 45k BTU furnace.

    These are jsut best guesses, you need a proper load calculation and ductwork design plan donw for your home. THis is oftne overlooked by builders. Homeowners don;t demand comfort or performance from HVAC, they focus on pretty flooring, layouts, bathrooms and countertops.

  12. #12
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,323
    Quote Originally Posted by 54regcab View Post
    My bad, I didn't realize it wasn't allowed in GA. Entire homes are often heated with strip in Oklahoma which ironically is colder than GA The only time I'm OK with heat strips as a primary heat source is for where it's rarely ran.
    I didn't actually say it was or wasn't allowed in any particular County or State...
    I just know it's Not allowed in New construction North of where I live in FL.

    OKlahoma seems to be a bit backwards in their building code.

    Consult your local Building Codes ... before one speaks !
    i.e.
    http://www.reedconstructiondata.com/...codes/georgia/
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  13. #13
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,372
    I wish it was national building code. Sure there would be a few installs that would never see a payback on heat pump vs. strips, but it would save big on most installs.

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