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  1. #1
    Join Date
    Jun 2008
    Posts
    23

    Air Conditioner questions

    What a great site. I'm a new homeowner, hence I am new to the HVAC world.

    I live in a ~ 1,500SF one floor house that has a "Comfortmaker" air conditioner and a Comfortmaker airhandler (in the attic). The house was built in 1996 and I purchased it last year.

    The air conditioning has always been really weak to me. I don't feel like the air is cold enough from the vents, and plus I think the airflow is terrible. The air handler is in the attic right above the master bedroom, and the airflow is just OK. However, the airflow is extremely weak througout the rest of the house. I have 10 ft ceilings and the only way to feel air from the vents is to put your hand right below the vents. I assume part of this problem is because there are no dampers in our ductwork (confirmed by the HVAC installer). However, even if I had dampers installed, I still feel like the airflow will be weak. I change my air filters religiously, and always make sure the outside air condition is free of debris. Am I missing something that might be hampering the air flow?

    Second , if the temperature outside of the house is 95 degrees, the house will never cool below 78 degrees even though the air conditioner runs constantly. For instance, the unit ran for 15 hours on Friday in 95 degree weather and never cooled the below 78 degrees. Could this be a refrigerant issue?

    I need some expert advice. I don't know if this is normal or if Comfortmaker is a horrible brand. I have heard it is the builder brand and therefore might be really cheap. I don't know the tonnage is of hand, but I can check if need be.

    I greatly appreciate your help! I feel clueless when it comes to HVAC.

    thanks!

    RK

  2. #2
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    Ductwork in the attic needs to be checked for leaks. A leaky return duct draws hot attic air into the system. A leaky supply ducts puts conditioned air into the attic, stealing the conditioned air from the rest of the house.

    Sounds like you have an installation problem and not necessarily a Carrier Comfortmaker problem.

    Good luck.

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,743
    Post outdoor units model number.
    It may not be sized to cool the house any lower then what it did when its 95 outside.
    You could have undersized ductwork.
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    How many times must one fix something before it is fixed?

  4. #4
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Location?
    Model numbers?
    Filter size and location?
    Main return and supply duct size?
    Pics of air handler and connecting ducts ,if you can?

  5. #5
    Join Date
    Jun 2008
    Posts
    23
    Thanks for all of the replies. Here is the information I have ascertained thus far.

    Air conditioner information:

    1. Model No: ACS036A2C1
    2. Mfr. No: NACS036A2c1
    3. Shipping charge R22 83 oz.

    Filter sizes (2):

    1. Near master bedroom (12x12x1) <closest to air handler>
    2. Other side of house (very weak air flow) (20x20x1) <furtherest away from air handler>

    I live near Greensboro, NC. I hope this information helps. Do you think my unit is undersized? Any way to determining if I have leaky ducts?

    Thank you again for your help.

  6. #6
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,888
    A 3-ton system should have 200-sq.ins. per ton or at least 600-sq.ins total for the filter racks.

    You have 544 sq.ins so that should not be the cause of the very low airflow.
    Look for duct leaks, correct sized boots & diffusers.

    I wonder if the blower is on high speed?

    Don't blame it on the equipment, it is usually an equipment setup &/or duct system problem.

    If the airflow is too low it could be delivering 2-ton or less.

    There are plenty of ways for a competent Tech to solve the problems & regain optimal A/C performance.

    There are a lot of good tips in the other posts.

    http://www.udarrell.com/proper_cfm_b...g_systems.html
    - udarrell

  7. #7
    Join Date
    Jun 2008
    Posts
    23
    Quote Originally Posted by udarrell View Post
    A 3-ton system should have 200-sq.ins. per ton or at least 600-sq.ins total for the filter racks.

    You have 544 sq.ins so that should not be the cause of the very low airflow.
    Look for duct leaks, correct sized boots & diffusers.

    I wonder if the blower is on high speed?

    Don't blame it on the equipment, it is usually an equipment setup &/or duct system problem.

    If the airflow is too low it could be delivering 2-ton or less.

    There are plenty of ways for a competent Tech to solve the problems & regain optimal A/C performance.

    There are a lot of good tips in the other posts.

    http://www.udarrell.com/proper_cfm_b...g_systems.html
    - udarrell

    I think you are 100% correct. It's more of an installation problem (ductwork). As I have stated in previous posts, my ductwork only consists of flex. I have two flex runs from the plenum. One duct runs to the master suite. The other main duct runs through the rest of the house. It is a line of flex duct connected to a distribution box, then more flex running to another distribution box. Air flow is terrible in the rest of the house.

    I had dampers installed on the branch runs for the registers in the master suite. It definitely helped cutting the air flow down in the master suite. Also, I had the blower set to "high" for cooling, so that helps for additional air flow throughout the house. I have the dampers adjusted to about 60% capacity for the two registers in the master suite and one register in the bathroom. The registers in the water closet and master closet are completely shut off. Do you think this will be OK? or is this hurting my system? I get a little nervous cutting a lot of airflow off ,but my hope is that it will push the air through the other flex run going to the rest of the house.

    Regardless, please correct me if I am wrong, but I would really prefer one large metal trunk to feed all registers in the house (with dampers installed at each branch run). I feel this would be the best way to get proper air flow throughout the house.

    One additional question. How would I know if a flex duct is constricted in any way? The large duct run that runs the entire length of the house was never supported. It just layed on the floor joists and was partially wrapped around a roof truss. I recently had the duct supported by straps, but I feel as if one part of the duct sticks out more than the other. IN other words, it doesn't feel round, but feel like something is sticking out. Granted, the duct had been just lying on the floor joist and partially wrapped around the truss for about 12 years. I wonder if this is partially constricting air flow throughout the rest of the house. what do you think? I am attaching some pictures of the duct. The duct I am referring to is the large one on the bottom. This is now supported and not kinking like that (I will take more pictures and post the results); however, this is the before picture. Do you think this did irrevocable damage and needs to be replaced?

    You guys are a world of knowledge! Thanks for your help.
    Attached Images Attached Images    

  8. #8
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    What size return and supply trunks ??

    Can you get a pic of the distribution box??

    Two distribution boxes in one trunk is twice the equivalent fewet(think resistance to airflow),as the one to the master.This means the trunk duct should be much larger,for the the cfms required,relative to the master.

  9. #9
    Join Date
    Jun 2008
    Posts
    23
    Quote Originally Posted by dash View Post
    What size return and supply trunks ??

    Can you get a pic of the distribution box??

    Two distribution boxes in one trunk is twice the equivalent fewet(think resistance to airflow),as the one to the master.This means the trunk duct should be much larger,for the the cfms required,relative to the master.
    Please see the attached pictures. Hopefully, the ducts are better supported. What do you think? I have taken some pictures of the distribution boxes. As you can see, the flex line on top of the plenum feeds the master suite (five branches from that distribution box). The flex on the side of the plenum (that makes the 90 degree turn) feeds the rest of the house. It runs to one distribution box (three branches off of it) and then runs to another distribution box (I think four branches from there)

    How can I tell what size the supply and return ducts are? The branches were clearly marked with the size, but the main supply and return ducts do not have any labels. Any help is much appreciated.

    Again, 3 ton air conditioner (comfortmaker), roughly 1,500 SF house near Greensboro (triad) NC.

    Thanks!

    http://img291.imageshack.us/img291/3088/nsd2ik8.jpg
    http://img84.imageshack.us/img84/768...edduct1id2.jpg
    http://img293.imageshack.us/img293/6...ibutionbk6.jpg
    http://img261.imageshack.us/img261/1...ibutionjk4.jpg
    http://img237.imageshack.us/img237/1...closeupaw8.jpg
    http://img179.imageshack.us/img179/7...ibutionbi9.jpg
    http://img291.imageshack.us/img291/4...tionboxpo2.jpg
    http://img179.imageshack.us/img179/7...distribbb9.jpg
    http://img529.imageshack.us/img529/5...distribcq9.jpg
    http://img208.imageshack.us/img208/9180/setup1ix2.jpg
    http://img209.imageshack.us/img209/8984/setup2lf1.jpg

  10. #10
    Join Date
    Jan 2008
    Location
    Dothan, Alabama
    Posts
    25
    If the air doesnt feel cool it could be because the fan speed is set on high for cooling . Not enough time for heat transfer

  11. #11
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    Ducts look to be on the smal side.

    What sizes are used for each "main" trunk,not the branches.

  12. #12
    Join Date
    Jun 2008
    Posts
    23
    Quote Originally Posted by dash View Post
    Ducts look to be on the smal side.

    What sizes are used for each "main" trunk,not the branches.
    I'm not sure. The branch lines were clearly marked on the outside, but the main trunk lines have no indication of size on the outside. What is the easiest way to measure the size of these trunk lines?

    My guess would be to peel back the insulation and with a tape measure, measure around the flex duct connected to the collar or takeoff; however, the insulation is wire tied very close the box and the only way to get to the flex duct would be to cut the wire tie. Surely, there is an easier way.

  13. #13
    Join Date
    Apr 2008
    Location
    TEXAS
    Posts
    1,701
    maybe after 12+years the evap just needs cleaning. get your tech to check for pressure drop across the evap coil. while he's at it he can check cfm @ each register.
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