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  1. #1

    2 zone system issues - sizing/cooling questions

    Good Afternoon,

    I own a 4200sq ft home in NJ. The home has a two-story family room in the middle, and a two-story open center hall. I have a two-zone HVAC system.

    The home was built in 2005. It uses Goodman HVAC equipment. The two outside AC units are 3 ton and 4 ton. Since day one, the home has heated fine in the winter, but summer has been a nightmear.

    Whenever it would get above 90 degrees outside, the upstairs of the home would have trouble getting down below 77 degrees inside upstairs. Downstairs would cool nicely, and the downstairs unit would cycle, but the upstairs unit would run forever. Even with both zones set to the same target temp of 74 degrees.

    The home receives a lot of sun all day long, as there are no trees close by. The units were located at the rear NW corner of my home, facing direct sunlight all afternoon.

    After the first year, I needed to have the two compressors (which are located next to each other) moved from one side of the NW corner to the other due to them being in the way of a major deck project. Simple task, since the line sets were in the basement, and only needed to be cut, pulled into the basement, shortened about 5 ft each, then fed thru the outside wall around the corner. I had an HVAC tech relocate the units and recharge the system.

    One advantage of the move (I thought) was that the new location places the compressors just behind a fence that shades them from direct sunlight, so I was thinking that maybe getting them out of direct sunlight all day might improve overall operation and efficiency. Yes, no??

    Since the move was done in the fall, I had the tech come back out in May the following season to charge them, and they seemed to work a little better than the previous season, but my upstairs zone never seemed to cool adequately as compared to my neighbors' similar sized homes.

    Fast forward to May 2008, and now again I'm having difficulty. The other day it hit the upper 70s, and the upstairs unit would not cool down to below 77 degrees. Finally, when it hit the low 60s outside, I was able to get the upstairs down to 73 degrees or so.

    My first thought is that either the system needs a charge again, or this system is just garbage.

    Now, I think I may have discovered another alarming issue - I think the tech who performed the relocation/move may have reversed the upstairs and downstairs compressors. Right now, the downstairs system is tied to the 4-ton Goodman unit, and the upstairs system is tied to the 3-ton outdoor unit. Which zone should be using the larger compressor - upstairs or downstairs??

    I'm an electrician, but my common sense leads me to think that since heat rises, the upstairs unit should be the larger unit, no? The other reason I think he goofed is that when the house was first built, the upstairs unit needed to be replaced when we moved in as it was defective from the factory, and that unit would be newer. The 4-ton unit's serial number is a year newer, and both numbers match close to the installation date timeframes, so that almost confirms my suspisions.

    Another question - when he relocated the units, he removed the line dryer filters internal to the Goodman units and installed new ones outside of the compressor cabinets. Was this necessary when cutting and re-brazing the line sets?


    Any thoughts on the subject?

    Thanks
    Radiodoctor

  2. #2
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,398
    It's hard to say which unit does what. There is no rule of thumb on having the larger unit up or down. Is the upstairs bigger or smaller? What is the layout of the house? It's possible he reversed the units. Who knows? You need to get somebody out to evaluate the situation. Maybe they are undersized? Unless somebody on here is close to you and can come visit your home, there isn't much that can be done on here to fix your problem. As far as replacing the internal filter dryers, I wouldn't do that. I would replace the external ones, but I wouldn't think that would be your problem, unless they are now undercharged.

  3. #3
    Join Date
    Sep 2003
    Posts
    132

    Confused

    Where is the upstairs fancoil or blower? If it is downstairs, I would bet your ductwork is not large enough. Try putting the blower on continuous fan and see if that helps.

  4. #4
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    5,987

    Thumbs up Model numbers will confirm set-ups / mis-match

    Quote Originally Posted by radiodoctor View Post
    4200sq ft home in NJ
    two-story family room in the middle, and a two-story open center hall.
    home was built in 2005
    Goodman HVAC equipment.

    The two outside AC units are 3 ton and 4 ton.
    Since day one, the home has heated fine in the winter, but summer has been a nightmare.

    Downstairs would cool nicely, and the downstairs unit would cycle,
    but the upstairs unit would run forever.
    Even with both zones set to the same target temp of 74 degrees.

    Fast forward to May 2008, and now again I'm having difficulty.
    ...
    My first thought is that either the system needs a charge again, or this system is just garbage.

    Now, I think I may have discovered another alarming issue - I think the tech who performed the relocation/move may have reversed the upstairs and downstairs compressors. Right now, the downstairs system is tied to the 4-ton Goodman unit, and the upstairs system is tied to the 3-ton outdoor unit. Which zone should be using the larger compressor - upstairs or downstairs??

    I'm an electrician, but my common sense leads me to think that since heat rises, the upstairs unit should be the larger unit, no?

    The other reason I think he goofed is that when the house was first built,
    the upstairs unit needed to be replaced when we moved in as it was defective from the factory, and that unit would be newer. The 4-ton unit's serial number is a year newer, and both numbers match close to the installation date timeframes, so that almost confirms my suspisions.
    What are the model numbers for each of the air handlers /compressors?

    _________________ Air Handler ... ... ... ... ... Compressor
    Upstairs ...... Goodman ___ _____ x-ton ... ... ____ __________ 3-ton
    Downstairs ... Goodman ___ _____ y-Ton ... ... ____ __________ 4-ton
    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

  5. #5
    Join Date
    Dec 2007
    Posts
    89
    get a good tech out to ur house whos willing to take the time to figure it out! Sorry, im in va. I will advise u to mention to the tech to check the air circulation of this system.

  6. #6
    Thanks for the quick replies....

    Dan -The current configuration is as follows:

    Upstairs Zone - CAPF042C2A air unit in attic, CKL-36-1L outside compressor
    Downstairs Zone - CAPF042C2A air unit in basement, CKL-42-1L outside compressor

    I tried searching Goodman's web site, but it looks like my units are older and not listed anymore.

    4Jime - the upstairs zone unit is in the attic. Centrally located above the center hall ceiling. The ductwork is covered in insulation and a plastic-bag like black wrapping. No visible duct issues I can see. Heating seems to work fine.

    I know this is not a DIY place, but I'm a quick learner, and

    Any good HVAC techs in Ocean County, NJ on board here?


    Thanks
    Radiodoctor

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,755
    That 42 is a 3.5 ton condenser, not a 4 ton.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    Mar 2008
    Location
    Central Maryland
    Posts
    246
    Quote Originally Posted by radiodoctor View Post
    My first thought is that either the system needs a charge again, or this system is just garbage.

    ...

    Any thoughts on the subject?

    Thanks
    Radiodoctor
    Yes- it's not a battery. If it needs constant recharging, it's broken. If it's run broken, it will break more.

    However, I have found (from personal experience) that there are plenty of techs that are happy to add a charge, whether the system needs one or not. Running overcharged doesn't help, either.

    After overcharging, they will be happy to sell you a new system to replace your "broken" one.

    -HF

  9. #9
    Dan - any comments on the matching of inside/ouside units based on the info?

  10. #10
    Join Date
    Jun 2009
    Location
    Kansas City, MO
    Posts
    2

    Source of airflow

    Many times in residential applications, ample thought is not given by installers to make the most of a heating/cooling fan coil. A few good determining factors are the following.

    1. Where is the air coming from? Are you pulling air (Return Air) from naturally cooler areas in your home? Do you have any fresh Outside Air coming in to your fan coil? If so, is there a damper installed to minimize that amount?

    2. Although your duct is what is known as flex-duct and is used in nearly every residential application in order to reduce cost, it creates a large amount of resistance to your total airflow and can hinder system performance. The best applications are sheetmetal ductwork wrapped in insulation.

    3. Check your grille dampers. Those fancy little white grilles that spill cool air into each room are often closed down during some seasons and forgotten later. I would BEGIN by checking every grille to see if they are all completely open. Then you can close certain ones "partially" in order to increase the airflow to other areas. Just remember that closing off too many of these can reduce your total airflow.

    4. Check filters. A common enemy of cool air circulation is dirty filters and/or dirty and clogged coils. It sounds like you have a pretty new system so if you look in your fan coil, you should have a shiny silver coil free of dirt dust and debris. Also, all filters should be changed religiously every 3 months or so.

    These are some simple steps that hopefully will help you out. Try all the easy steps first and before comitting to spending any large amount of money, have a technician with a good reputation analyze your total system. I hope this helps and best of luck.

    Dan Kennedy

  11. #11
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    5,987

    Hmm Complex due to family room

    Quote Originally Posted by radiodoctor View Post
    Good Afternoon,

    I own a 4200sq ft home in NJ. The home has a two-story family room in the middle, and a two-story open center hall.
    The home was built in 2005. It uses Goodman HVAC equipment.

    Whenever it would get above 90 degrees outside, the upstairs of the home would have trouble getting down below 77 degrees inside upstairs. Downstairs would cool nicely, and the downstairs unit would cycle, but the upstairs unit would run forever. Even with both zones set to the same target temp of 74 degrees.

    After the first year, I needed to have the two compressors (which are located next to each other) moved from one side of the NW corner to the other due to them being in the way of a major deck project.

    Fast forward to May 2008, and now again I'm having difficulty. The other day it hit the upper 70s, and the upstairs unit would not cool down to below 77 degrees. Finally, when it hit the low 60s outside, I was able to get the upstairs down to 73 degrees or so.

    My first thought is that either the system needs a charge again, or this system is just garbage.

    Now, I think I may have discovered another alarming issue - I think the tech who performed the relocation/move may have reversed the upstairs and downstairs compressors. Right now, the downstairs system is tied to the 4-ton Goodman unit, and the upstairs system is tied to the 3-ton outdoor unit. Which zone should be using the larger compressor - upstairs or downstairs??

    I'm an electrician, but my common sense leads me to think that since heat rises, the upstairs unit should be the larger unit, no? The other reason I think he goofed is that when the house was first built, the upstairs unit needed to be replaced when we moved in as it was defective

    Another question - when he relocated the units, he removed the line dryer filters internal to the Goodman units and installed new ones outside of the compressor cabinets. Was this necessary when cutting and re-brazing the line sets?

    Any thoughts on the subject? Thanks Radiodoctor
    Air distribution is likley a real problem with a 2 story family room significantly complicating the situation.

    It would take several hours to model and analyze the overall cooling load and the amount of air required for each room. AND then the ductwork and air distribution would have to be addressed.

    You need someone who has dealt with large residences and this type of first floor/ second floor interaction to address your unique needs.
    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

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