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  1. #1
    Join Date
    Jun 2007
    Posts
    11

    Residential HVAC replacement Questions

    I had posted a few questions here about 3 weeks ago and got a lot of good replies. Thanks a lot.

    Now, I have decided to replace my entire AC unit, also the furnace. Considering long term expenses and the federal rebate, this seems to make better sense.

    One of the contractor did a load analysis (don't know if its mechanical D or mechanical J). I had to measure all my windows and doors, specify geographical north. He ran the numbers and said that my tonnage requirement is 4.79, which means I am going for a 5 ton unit.

    Bunch of more questions;
    Background:
    I have a single unit with zoning for the two floors of the house - there is a thermostat control for each floor.

    Quote 1:
    One contractor is recommending AC model - 2YABC660 ( or is it 2VABC660?) condenser and CNPHP6124ATA (coils) from Carrier. The furnace (and blower motor) is going to be 58PHA110-120 from Carrier as well.

    Quote 2:
    The other contractor is recommending a 4 ton unit with 24ABC648A (condenser), CSPHP6012(coils) from Carrier. The furnace is 58PHA110. The second contractor is recommending that I have to install a bypass duct work as well. He says that when a single zone is blowing, there is not sufficient air flow over the coils and the equipment doesn't function properly. This costs me an additional $.

    So, my question is, is it necessary to get this bypass duct work? Further, is there any other load analysis that needs to be done before I make a decision?

    Thanks in advance.
    -CN3701
    Last edited by beenthere; 07-04-2010 at 04:16 PM. Reason: price

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,712
    So your zoning system currently doesn't have a bypass?

    Most non modulating zoning systems need a bypass. Or a dump zone.

    Some systems though, are designed that they don't need it. Can't tell how yours was designed.
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  3. #3

    Williamson 5-in-1 Furnace Parts

    I have a Williamson 5-in-1 furnace that the printed circuit board has burned. I have the parts number and was wondering where I could obtain another printed circuit board? I have the part number. It is HH84005. I am located in Cincinnati, Ohio and was wondering if anyone could give me some information?

  4. #4
    Join Date
    May 2010
    Location
    SF Bay Area, CA
    Posts
    390
    Quote Originally Posted by go2gurl View Post
    I have a Williamson 5-in-1 furnace that the printed circuit board has burned. I have the parts number and was wondering where I could obtain another printed circuit board? I have the part number. It is HH84005. I am located in Cincinnati, Ohio and was wondering if anyone could give me some information?
    you should make a new thread so your Q has a better chance of being seen.

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,712
    She can call a contractor, and the contractor can sell and install a new board for her.
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    How-to-apply-for-Professional

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

  6. #6
    Join Date
    May 2010
    Location
    New Jersey
    Posts
    1,309
    24ABC660 is a 5-ton, -24ABC648 is a 4-ton.

  7. #7
    Join Date
    Jun 2007
    Posts
    11
    Beenthere,

    Thanks for the reply. My current zoning has a control which is a PCB. The zoning, I am told is a on-off damper system. It shuts off the entire floor if cooling is not needed there.

    So, the contractor is suggesting that the additional duct work is to capture some of the air and bring it back to the coil. At least, that's my understanding.

    -CN3701

  8. #8
    Join Date
    Jun 2007
    Posts
    11

    Thanks

    Quote Originally Posted by DavidNJ View Post
    24ABC660 is a 5-ton, -24ABC648 is a 4-ton.
    Thanks.

  9. #9
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,829
    We don't have sufficient information from your post to determine if the 4 or 5 ton unit is most appropriate. You said, one contractor said, 4.79 tons. That's between 4 and 5-tons and being in NJ, I don't know if that includes an adjustment for a lower design temperature or not. So the contractor who did the load analysis is definitely the one to work with. Forget any other. You just need to determine from the load analysis whether the sensible heat ration (SHR) has been adjusted for New Jersey or not. If not, then it's likely a 4-ton unit will do the job. If it has been adjusted the you definitely need a 5-ton unit.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  10. #10
    Join Date
    Dec 2006
    Location
    Middle Tennessee
    Posts
    11,347
    Quote Originally Posted by cn3701 View Post
    Now, I have decided to replace my entire AC unit, also the furnace.

    One of the contractor did a load analysis (don't know if its mechanical D or mechanical J). He ran the numbers and said that my tonnage requirement is 4.79, which means I am going for a 5 ton unit.

    I have a single unit with zoning for the two floors of the house - there is a thermostat control for each floor.

    Quote 1:
    One contractor is recommending AC model - 2YABC660 ( or is it 2VABC660?) condenser and CNPHP6124ATA (coils) from Carrier. The furnace (and blower motor) is going to be 58PHA110-120 from Carrier as well.

    Quote 2:
    The other contractor is recommending a 4 ton unit with 24ABC648A (condenser), CSPHP6012(coils) from Carrier. The furnace is 58PHA110. The second contractor is recommending that I have to install a bypass duct work as well. He says that when a single zone is blowing, there is not sufficient air flow over the coils and the equipment doesn't function properly. This costs me an additional $.

    So, my question is, is it necessary to get this bypass duct work? Further, is there any other load analysis that needs to be done before I make a decision?

    Thanks in advance.
    -CN3701
    what is the size of your current system, if your not sure, tell us the model and serial number

    depending on your controller, plus the style of system you have, is what will determine the need for bypass option

    if you have a 2 speed system that runs 50% on low speed with 2 zones of the same size and a "smart" controller you won't need a bypass or dump zone

    otherwise your gonna need some sort of bypass

    or even a dump zone which kills efficiency more than a bypass!



    .

  11. #11
    Join Date
    Jun 2007
    Posts
    11
    Quote Originally Posted by Airmechanical View Post
    what is the size of your current system, if your not sure, tell us the model and serial number

    depending on your controller, plus the style of system you have, is what will determine the need for bypass option

    if you have a 2 speed system that runs 50% on low speed with 2 zones of the same size and a "smart" controller you won't need a bypass or dump zone

    otherwise your gonna need some sort of bypass

    or even a dump zone which kills efficiency more than a bypass!



    .
    Thanks for the reply. The current system I have is a Goodman 5 Tonne system. It perhaps is a 12 SEER or something. This was installed by the builder when the house was built 10 years ago.

    The estimates I mentioned earlier are for single speed systems. What do you mean by some sort of by-pass? What is dump zone?
    Appreciate the answers.
    -CN3701

  12. #12
    Join Date
    Jun 2007
    Posts
    11

    Frown

    Quote Originally Posted by skippedover View Post
    We don't have sufficient information from your post to determine if the 4 or 5 ton unit is most appropriate. You said, one contractor said, 4.79 tons. That's between 4 and 5-tons and being in NJ, I don't know if that includes an adjustment for a lower design temperature or not. So the contractor who did the load analysis is definitely the one to work with. Forget any other. You just need to determine from the load analysis whether the sensible heat ration (SHR) has been adjusted for New Jersey or not. If not, then it's likely a 4-ton unit will do the job. If it has been adjusted the you definitely need a 5-ton unit.
    Thanks. I live in central Texas where gets hotter than NJ.
    In any case, my current unit is a Goodman 5 Ton, 12 SEER unit. I have been told that in order to qualify for credit from the Fed, I have to get a 16 SEER system. My question primarily is about the need for a bypass duct/damp zone.

    -cn3701

  13. #13
    Join Date
    May 2010
    Location
    SF Bay Area, CA
    Posts
    390
    Quote Originally Posted by cn3701 View Post
    Thanks. I live in central Texas where gets hotter than NJ.
    In any case, my current unit is a Goodman 5 Ton, 12 SEER unit. I have been told that in order to qualify for credit from the Fed, I have to get a 16 SEER system. My question primarily is about the need for a bypass duct/damp zone.

    -cn3701
    what kind of zoning panel do you have?

    a bypass or dump zone is, as contractor #2 said, to relieve excess pressure and provide adequate airflow over the coil / heat exchanger when only one zone is calling.

    the bypass sends air from the supply plenum to the return plenum and it should be obvious if you have this already with some duct work at your furnace. there is usually some kind of barometric damper that will open as static pressure rises on the supply side.

    a dump zone are some supply registers not connected to either of you zone dampers. this is an "always open" section of your ducting. as Airmechanical says, this isn't best for efficiency.

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