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  1. #14
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,120

    Read this before you hook up that unit.




    hvac r us 2
    ** Site Supporter **

    Registered: Apr 2004
    Posts: 388
    This is the most annoying thread I have read to date.

    I am a Carrier rep, and let me tell you 80% of everything in this thread is nonsense!

    First off I agree with Doc, regardless of how much equipment you buy as a dealer if you do it wrong we will point it out. Of course we would never hang a dealer out to a homeowner, but in private we would show the dealer where the mistakes have been made. Any good dealer would take our advice as they want the problem to be resolved/corrected.

    This is NOT Carriers fault, they have already paid for several compressors. Your mad at Carrier? Why not go after and be mad at the installing contractor? They screwed up! And as I already stated, a good contractor would fix this problem if he knows he did it wrong.

    What more can Carrier do? I mean really, they put it in the instructions, they instruct the dealers, they train them, and they have already spent thousands on giving you replacement compressors! What more do you want from Carrier? Again I ask you, why are you blaming Carrier? Your one of those people that will bash Carrier, when the only real problem is your installing contractor and you.

    What part of don't bury the line set dont you get? Seriously? Stop with the Trane this and that, there are factors you just refuse to acknowledge. Like the fact that it is a two speed unit? What do you think happens when you have low pumping capacity? Think about it...you have a system that has piping, indoor coil, metering device, all designed for the full capacity of the unit. When it runs on low stage it is already hard to control the Superheat without a buried line set where refrigerant can migrate. You keep complaining you didnt know about buried line sets, but you do now and yet you wont listen.

    And you genuisses out there, do this, do that...your kidding me right? Add this, add that, put on an external accumulator...huh? In certain applications that may work.

    Not sure, but did I mention the part about being a two speed unit? It already has an accumulator. Let's add another one to the suction line in a series...that should help oil return.

    I assume like so many others you didnt notice the part in Tranes piping guidlines that said in BOLD letters " It is advisable to avoid running refrigerant lines underground" Wonder why they put that in there? In certian areas buried lines just dont work...like Ohio.

    You got the correct advise in the begining of this thread, but refuse to take it. I predict you will carry on only hearing what you want to hear, you will loose more compressors, and blame Carrier for selling you a lemon.

    You didnt buy a lemon, you created one.

    Amazing, just amazing...people ask for help, you help them, then they dont listen anyhow.

    Amazing...


    __________________
    If I can't fix it, it isn't broke!


    06-28-2004 09:11 AM
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  2. #15
    Join Date
    May 2004
    Posts
    137
    " I assume like so many others you didnt notice the part in Tranes piping guidlines that said in BOLD letters " It is advisable to avoid running refrigerant lines underground" Wonder why they put that in there? In certian areas buried lines just dont work...like Ohio. "

    You might find yourself asking:

    How does the AC know if the lines are underground vs. being run from
    an elevated air handler along a lower plane to a raised condenser?

    It can't !!!

    Wonder what Ohio dirt has that other states dirt doesn't?

    There ARE issues concerning electrolysis, oil return, access,
    water table, drainage, etc.;

    therefore it is not advisable to bury the refrigerant lines;

    BUT a properly designed piping system can be installed on any plane.

    Underground insulated refrigerant lines enclosed in water tight PVC
    in an area not subject to water would be Better insulated and protected
    from ambient elements than lines above ground.

    NO ONE
    will post a physical, scientific explanation why it can not be done.

    As I have seen MANY installations with lines run underground that have
    been in trouble free operation for over 20 years with NO problems;

    I am waiting for substantial proof that I stand to be corrected.

    Have a Great day

  3. #16
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,120
    Lines are buried in slabs, under slabs, and in alot of other (strange)set ups, but most are done with the guidence and ok from the manufacturer.

    I've run 180' line sets, but with the manufacturers ok.
    Get approval is what i have been telling this guy.
    The tech coming out may have no idea whats going on, and just start this thing up, then the guy could lose his warranty.
    And all he would he needs to do is make a phone call, or have the tech make it.

    Without either a non bleed txv, or a LL selinoid valve, he will have liquid migration.
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  4. #17
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856
    Linesets in PVC and incased in concrete are not really "buried" are they? They will not have direct contact with the earth! You could make it work by putting a little heat in the PVC to keep ref. from condensing ie.. heat tape.
    Karst means cave. So, I search for caves.

  5. #18
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,120
    Its not just the direct contact, its also the temp, and heat tape might work. Also, most under ground lines are also big oil traps, so some times you have to resize your line sets, and add x amount of oil.


    Maybe i'm paranoid, but we call the manufacturer first, and give them a drawing of the line set runm and then make any changes, or what ever they said from there, and keep the warranty intack by doing this.

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  6. #19
    Join Date
    Jul 2004
    Location
    MN
    Posts
    17
    Some conclusions:

    The general elevation profile of the lines will be similar if I route them in an alternative manner around the outside of the house (it will just look uglier), so I am not buying the issue of the buried line set being any worse of an oil trap than a conventional install in this case. The height difference between the indoor and outdoor coils is about 5 feet. That doesn't change regardless of how the lines are run. Both routings have no extra vertical sections (unless we intentionally add an inverted trap at the condensor).

    Encased in a sealed PVC pipe, the lines are not subject to direct contact with the ground, so corrosion is not an issue, nor is external water condensation.

    The only issue that makes sense for me to worry about that I have heard so far is that the lower temperature of being in the ground may cause the refrigerant to condense in the suction line and be drawn into the compressor in liquid vs. gas form.

    Going by the instructions that the unit is rated to be operated in ambient temperatures down to 55 F, I would assume that this would be a safe lower limit for the suction line temp.

    During the season when the unit will be in operation, I can't see the ground temp of something less than 12" deep going below 55 degrees. In fact, its probably subject to less temperature swing than a line hung bare on the outside of the house.

    So, I can half convince myself that it will probably work fine.

    On the other hand, if it voids the warranty and something fails (regardless of if its related to this issue), I am sure I will have wished I had done it the conventional way, even if it is much uglier.

    So, tomorrow AM, I will call the distributor and ask them about the warranty. If they indicate it won't be covered in this situation, its off to the rental shop to get a diamond coring bit to put a new 3" hole through 12" of concrete foundation on the side of the house above grade (unless the tech happens to have such tool in his truck).

    Thanks for the information.

    - Rick

  7. #20
    Join Date
    Jun 2004
    Posts
    420
    What about a liquid line solenoid and a pump-down cycle? If you pump all the refrigerant into the condensor/liquid line, it can't migrate to the suction line, right? Overkill for a residential system, but if thats what it takes....

  8. #21
    Join Date
    Jul 2004
    Location
    MN
    Posts
    17
    Does that mean that at the end of the call for cooling the liquid-line valve closes, while a delay relay leaves the compressor on for a few seconds? How long of a delay? Sounds easy enough if the valve is already going to be there.


  9. #22
    Join Date
    Jun 2004
    Posts
    420
    In a pump-down system, the thermostat controls the the solenoid and a pressure switch controls the compressor. Basically, at the end of the call, the solenoid closes, pumping all the refrigerant into the condensor. Once the suction pressure reaches, say, 5psi, the compressor shuts down.

    On the next call, the solenoid valve opens, causing the suction pressure to rise, and the compressor restarts.

    It's used on refrigeration units and some large commercial systems to stop liquid migration. Normally not on residential, but I don't see why you couldn't do it. Is this a straight cooling unit? You wouldn't be able to do pumpdown on a heat pump.

  10. #23
    Join Date
    Jul 2004
    Location
    MN
    Posts
    17
    Its cool-only, so pump-down may be an option.

    Does the LLS and pumpdown work on scroll compressors? Won't the pressure just equalize when the compressor shuts off?






  11. #24
    Join Date
    Mar 2002
    Location
    Concord, CA
    Posts
    2,635
    AFAIK know most or all new scrolls have check valves, so it shouldn't equalize through the compressor.

    I'm dying to hear BT or somone else on this pump down idea. A non-bleed TXV or LLS sounds like a solution. But a pumpdown setup sounds really interesting. The only thing I wonder is with all extra refrigerant that you'll have to add to compensate for the lineset length, will the condenser have the necessary internal volume to pump down without a problem (on a hot day for example)?

  12. #25
    Join Date
    Jun 2004
    Posts
    420
    You wouldn't have to pump it all into the condensor. Put the LLS right before the metering device, and you have the storage space of the liquid line also. All you'd be emptying would be the evaporator and the suction line, which isn't a lot of refrigerant.

    An LLS right at the evaporator or a non-bleed TXV might be sufficient, but you still have some liquid in the evaporator when it closes. With pumpdown, there is definately no liquid in the low side of the system.

  13. #26
    Join Date
    Mar 2002
    Posts
    127

    What more can Carrier do? I mean really, they put it in the instructions, they instruct the dealers, they train them,
    ...
    For one thing, be consistent.

    When I had a carrier condensor installed, the contract specified installation according to manufacturer's instructions and specifications. Install manual said a liquid line filter-drier must be installed. Contractor refused saying it wasn't necessary.

    Contacted Carrier tech support and they danced around the issue - said "should be OK if it's a new install" so contractor still refused to install one. I ended up hiring someone else after the fact to come in and install one.

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