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  1. #1
    Join Date
    Aug 2005
    Posts
    110
    Please correct any wrong statements. My business is in the changeover market. From my understanding..... in let's say a 13 year old hvac system with a bad compressor in the outdoor unit

    A 13 Seer outdoor unit is not compatible with the small indoor coil on the system so a new evaporator coil will need to be installed also. This is because the outdoor unit has much more freon than the indoor coil.

    The line set will also probaly need to be installed as well because the unit will require larger suction lines to return the freon to the unit.

    Due to larger Coils the units will not dehumidify as efficiently so the blower speed should be lowered in areas with high humidity.

    If these statement are true then what do I due if the furnace/coil are 14" wide and are located in a small 16" inch wide closet. The larger 17" coil won't fit. This is common where I work for two story condo's. Also many times these units have 5/8 x 3/8 Line sets. (old janitrol units)

    Where I work, There are big houses with small units in the attic for the upper level. They typically have a 80 - 100 foot line set run in between the walls. It seems that they will have to install the new line set outside the walls or have serious sheet rock and paint repairs.

    Please clarify anyone. There is too much conflicting information from techs, magazines, and distributors.

  2. #2
    Join Date
    Sep 2002
    Location
    South Dakota
    Posts
    6,579


    I guess if you want still more conflicting information, you came to the right place!

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,473
    We almost never reuse a 13 year old evap with a 10 SEER. Rarely reuse lines unless we can't change them. Our feeling is if we don't leave something old behind, it can't haunt us.

    2 ways to get high SEER, big evap or TXV. Big piston evaps will have trouble with humidity control. You should already be setting your blower to 400 CFM/ton though few do. It will be especially critical next year. Mfrs know that big evaps are a concern. I'm sure decent sized TXV coils will be around though not bottom dollar. With them, they can reduce size and humidity issues.

    This new stuff will help separate the hacks from the good installers. Trouble is some cheap homeowners are gonna be the recipients of the hack's work - justice in my book!

  4. #4
    Join Date
    Aug 2005
    Posts
    110
    Of course it's always good to replace the line set and coil when you replace the outdoor unit. But with 10 and 12 seer it is always an option.

    what about it cases where its going to be impossible to replace the lines and coil without having to destroy the house to do it. Like the examples in the other post or an undergroud line set, or a closet that is too small for the bigger coils.

    Do you rip everything out and put the system in the attic?


  5. #5
    Join Date
    Mar 2004
    Location
    CHICAGO SUBURBS
    Posts
    464
    Mr. frio ,I have the same questions as you. I ocasionally work for a property developer that is cheap cheap cheap and will not here of an evap. change or lineset change and there are lots of guys that will just change out the condensing unit around here.I know it,s not textbook but I've got kids and a dog to feed.I've not done it yet and don't yet know if I ever will but {I'll get abused for saying this here]my supplier claims only the seer rating will be off and it will still work.Before you beat me up guys, I said I don't do it and don't know if I will.I also have a lot of questins. What about townhouses?
    Some people swear by me and some at me

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,594
    A 13 seer condenser hooked to a 10 seer evap will cool.
    You won't get the seer of course.
    Its also possible that a 2 ton 13 seer condenser, will be reduced to 1.5 tons of cooling when hooked to that 10 seer evap.

    So if your going to do that, better get some thing in writing explaining that your doing a buyer beware install.


    But, the hacks will figure out the way to bypass the 13 seer rule.
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  7. #7
    Join Date
    Apr 2004
    Posts
    7,680
    I tell you this, if I had anything to do with warrantees, I would say current warrantees are fine for a complete system, but if you change just the outdoor section it would then be only a 1 year warranty on all parts including the compressor and a 90 day labor warranty like on any other replacement part.

    Certainly if you bought just a motor from GM and you wanted to stick it in your old ford pick up, they wouldnt give you a 3 year, 36,000 mile bumper to bumper warranty.

  8. #8
    I would find a compatable coil that was only 14 or 15 inches wide. Most units do not have only 1 coil match.

    As far as the lineset, I know that the units we install a 13 or 14 SEER does not require a larger line than a 10 SEER.

    T

  9. #9
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,964
    The smaller the evaporator, the less the efficiency. Since 13 SEER is going to be the minimum, manufacturers are not going to be rating combinations that are rated less. Bottom line is that there is not much chance of properly using a smaller coil.

    Most higher efficiency systems require larger refrigerant lines for full capacity.

    This is definitely a viable concern that is going to have to be addressed. There is nothing good that will come from trying to get around it.
    Government is a disease...
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    Ecclesiastes 10:2 NIV


  10. #10
    Join Date
    Aug 2005
    Posts
    110
    So 13 seer big unit = big amount of freon
    Small Evap Coil = small amount of freon
    Big 13 seer unit needs bigger freon lines to return the freon to the unit or else it starves the outdoor unit.

    In a lot of cases it won't be a problem but in some cases it will be very difficult to install the units properly.

    So if there are any manufacturer sales reps what do we do in townhomes, inaccesible line sets,or small confined spaces that won't accept a larger coil when required? In these cases I'm sure the homeowners could care less about the efficiency of their unit. I think they would like to replace their AC without destroying their house or paying 5k to 7k because their out door unit needs to be replaced.

    Do any 13 seer Units exist that will work without replacing the evap coil or line set?

    Has anyone thought of this or is it a secret that only a privledged few are in the know?

  11. #11
    Join Date
    Apr 2004
    Posts
    7,680
    I dont think I fully subscribe to the fact that you always need a bigger line set, the amount of heat transfer is still the same btuhs (for the most part). You will and always should refer to the installation requirements for each system.

    The coils will be larger, and the law is the law. There are no mfgs who are exempt.

  12. #12
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,964
    Keep in mind doc, the brand you rep is one that is engineered to use a minimum of refrigerant to get the job done. Most other brands require larger capacity coils and lines.

    As I stated; the smaller suction lines will only decrease the overall capacity of the system. This is a factor that even doc's brand recognizes and has capacity factor charts for. Smaller liquid lines become a problem when not enough liquid refrigerant is getting to the larger evaporator coils.

    This is an issue that manufacturers have recognized for years. The decision to have a minimum SEER rating of 13 SEER is not a manufacturing decision, but rather a Federal government decision.

    Manufacturers would love to be able to accomodate existing conditions. If any one manufacturer figures out how to utilize the smaller spaces mentioned and still get the minimum required efficiency, look for that manufacturer to pull well ahead of all of the others.

    In the meantime, those who have this space issue are the ones that are going to have to figure out how to resolve "their" problem.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  13. #13
    Join Date
    Aug 2005
    Posts
    110

    Hmm

    So now a XXXXXXX 10 seer Condensing Unit change out will become a XXXXXXXX dollar job. I'm guessing that 70% of the homeowners that would normally replace an outdoor unit with or with out a coil will find these options out of their price range. I think we'll make close to the same money because of the bigger jobs that will result from the 30% that will fork over the money to do the job.

    I think I'll invest in a company that produces window units. In a lot of cases I'm sure that blue collar workers or those with poor credit will have no other choice if they want cold air in summer.



    [Edited by lusker on 08-31-2005 at 10:13 AM]

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