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  1. #14
    Join Date
    Nov 2004
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    North Carolina
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    443
    Just out of curiosity, what is going to keep the compressor from overheating if you drop the suction line size by a quarter of an inch? Unless the manufacturer oversized the line (could happen I guess) it will strain the compressor & it will fail prematurely. Walk up to a unit with an undersized line & you can hear the difference. It sound's like it's working hard even when it shoulden't. (just my opinion)

  2. #15
    Join Date
    Nov 2006
    Location
    SC
    Posts
    930
    Goodman has recently upped the vapor line requirements. They DO spec them in the installation document. Sometimes it is enough to run PART of the line in the larger size. This is also covered in the installation doc.
    I recently installed a 5 ton Goodman. The new spec requires 1 1/8, the old was 7/8. The parts counter sent 7/8 to the jobsite after I specified 1 1/8. I sent one of my guys to exchange it, and he came back with the same 7/8! The counter guy was cocksure the 7/8 was the correct size.
    Yes, it will run on the smaller size. What will it cost you? Only the future will tell for sure. Some loss in efficiency and compressor life are probabilities.

  3. #16
    Join Date
    Nov 2000
    Location
    Eastern PA
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    Quote Originally Posted by gevans View Post
    Goodman has recently upped the vapor line requirements. They DO spec them in the installation document. Sometimes it is enough to run PART of the line in the larger size. This is also covered in the installation doc.
    I recently installed a 5 ton Goodman. The new spec requires 1 1/8, the old was 7/8. The parts counter sent 7/8 to the jobsite after I specified 1 1/8. I sent one of my guys to exchange it, and he came back with the same 7/8! The counter guy was cocksure the 7/8 was the correct size.
    Yes, it will run on the smaller size. What will it cost you? Only the future will tell for sure. Some loss in efficiency and compressor life are probabilities.
    No loss of efficiency or any compressor damage. The only thing a reduced vapor line does is to lessen the capacity of the system.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  4. #17
    Join Date
    Nov 2000
    Location
    Eastern PA
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    Quote Originally Posted by model m-man View Post
    Just out of curiosity, what is going to keep the compressor from overheating if you drop the suction line size by a quarter of an inch? Unless the manufacturer oversized the line (could happen I guess) it will strain the compressor & it will fail prematurely. Walk up to a unit with an undersized line & you can hear the difference. It sound's like it's working hard even when it shoulden't. (just my opinion)
    Your opinion has merit in logic but is not accurate. A smaller suction line decreases capacity but does not raise the teperature of the compressor as the system would have been charged according to parameters including the smaller suction line.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  5. #18
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    I'd think "loss of capacity" is directly related to loss "efficiency ".

  6. #19
    Join Date
    Jul 2004
    Location
    Massachusetts
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    6,829
    Quote Originally Posted by TLY View Post
    Well, it must have impacted something in a significant way. That is an increase of 33%. (3/4'' nominal to 1'' nominal) I would be interested to know what problems were solved or what efficiencies were increased by changing this specification.

    Specifications are a funny thing...some say they are of no real significance and some say they are critical...still confused.

    TLY
    Could it be that 1-1/8 is the next size up from 7/8 and if they wanted or needed 10% more, they HAD to move up 33%??????

    Specifications are there for a reason. But those who've been doing this for a while are all well aware that the man's all state that a reduction in line size will only lead to loss of capacity. Some even publish specs for 'undersized lines'.
    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!

  7. #20
    Join Date
    Nov 2007
    Posts
    47
    Quote Originally Posted by RoBoTeq View Post
    No loss of efficiency or any compressor damage. The only thing a reduced vapor line does is to lessen the capacity of the system.
    By how much is the capacity lessened?

  8. #21
    Join Date
    Jan 2007
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    N.E. Ok.
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    1,359
    Quote Originally Posted by TLY View Post
    By how much is the capacity lessened?
    Wiithout looking it up i think this is probably real close.

    Quote Originally Posted by dash View Post
    Check the mfrs. specs,might just be a 3% capacity loss.

  9. #22
    Join Date
    Nov 2007
    Posts
    47
    Quote Originally Posted by captube View Post
    Wiithout looking it up i think this is probably real close.
    So does that mean a 4 ton unit will function like a 3.88 ton unit? Also, are sensible and latent cooling capacities equally affected, or is one affected more than the other?

    Thanks,
    TLY

  10. #23
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    Nov 2000
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    Eastern PA
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    Quote Originally Posted by dash View Post
    I'd think "loss of capacity" is directly related to loss "efficiency ".
    I've checked into that and am told that if that were the case that manufacturer's would have to state as much in the charts. It seems that the amount of capacity decrease causes lower power consumption at the same time. More then likely a matter of how much refrigerant is being pushed through the system being less with a smaller line.

    Either way, it is too minimal to calculate in the field.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  11. #24
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    Nov 2000
    Location
    Eastern PA
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    Quote Originally Posted by TLY View Post
    By how much is the capacity lessened?
    On a 50' line the capacity using 7/8" instead of 1-1/8" is 97% of full capacity.

    So, if a 3 ton unit actually did produce 36,000 Btu of cooling (which they don't), it would only produce 34,920 Btu of cooling using a 7/8" suction line.

    Do not mess with the liquid line though. Big difference between liquid and vapor.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  12. #25
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    Quote Originally Posted by RoBoTeq View Post
    I've checked into that and am told that if that were the case that manufacturer's would have to state as much in the charts. It seems that the amount of capacity decrease causes lower power consumption at the same time. More then likely a matter of how much refrigerant is being pushed through the system being less with a smaller line.

    Either way, it is too minimal to calculate in the field.
    I'd have thought differently,but I'll accept thtat since you say so.

  13. #26
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    Nov 2000
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    Eastern PA
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    Quote Originally Posted by dash View Post
    I'd have thought differently,but I'll accept thtat since you say so.
    I'm not making this a fact. Just an assumption based on heresay and manufacturer's not addressing it any differently. What you state makes sense as well. Then again, I urge techs to lower indoor airflow to increase latent heat removal which also reduces efficiency.

    Sometimes it's not all about efficiency
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


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