interpreting dealer ground loop design

Discussion in 'Vertical and Horizontal Loops' started by gjinc, Jan 25, 2013.

  1. gjinc

    gjinc New Member

    Hi
    I need a little help understanding this.
    Dealer recommended a 5 ton unit
    his loop source is -horiz 0.75"-4 pipe
    soil type is - Heavy Soil Damp
    Average Depth - 5 feet
    Loop temp Min-Max - 27 96 F
    Trench length - 695 feet

    Ok, here is what I understand, please correct me if I am wrong
    Going to do a horizontal ground loop using 3/4 inch pipe set in at 5 feet with 4 pipes going 695 feet, A total of 2780 feet of loop
    I am guessing that the pipe needs to be 12 inches apart
    And I read somewhere that a single loop should not be more than 800 feet, correct or nonsense?

    Thank You
    Greg
     
  2. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    500-600 feet is about as long as you want to go with .75 pipe
     
  3. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    A loop per ton. Dewayne is correct. Pumping issues occur at 300' for 1/2" and 500' for 3/4".

    I want 10' preferably 15' of separation between loops.

    Depth depends on dirt and climate.

    Your mileage may very.

    Mark
     
  4. gjinc

    gjinc New Member

    Thanks!
    so basically, this loop will not work. Since it has a trench length of 695 feet and 3/4" tubing is only good for 500 feet.
     
  5. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    it will work, just very inefficiently . The loop pumps will need to be oversized.
     
  6. gjinc

    gjinc New Member

    Well, guess I need to talk to a couple more contractors.
    makes me wonder what else is insfficient
    Thank You
     
  7. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    What is wrong with a loop like that?. 4 parallel circuits, 700 ft length each? Sounds reasonable, depending where you are, your load. With a (2) pump 26-99 flowcenter, you should get around 14.25 gpm. While I would try to design for a single pump flow center, once you go to a 2 pump flocenter, this design will perform OK.
     
  8. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    I would not hit the panic button just yet, if it is a typo and he meant to spec 1" pipe, your numbers to pump will be alot better.
    Eric
     
  9. gjinc

    gjinc New Member

    Thanks
    I am not panicking, just getting frustrated, every contractor that i have talk to seems to have there own way of wanting to do it.
    seems there is no industry standard. One even said 1 loop 3000ft long, wonder what size pump that would need.
    I have talk to people who love theirs and I've talk to people who say they are not saving anything
    If it is not going to be efficient then whats the point?
     
  10. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    By identifying the disparity between design and execution, you are allready miles ahead of the game. Be patient and stay at it, the right guy for your project is out there.
    Eric
     
  11. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    There are absolutely industry design standards. Several. There are many ways to "skin each cat". You are focused on loops without telling us things that are really important such as how did each contractors references check out? Who measured the whole house for a load calc etc.
    I have mentioned more than once before that our emphasis on loop design can sometimes turn a potential buyers attention from what matters most.
     
  12. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    This makes me think I must be the only one that doesn't include design data in a quote.
     
  13. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Chris:

    What is design data?

    lol

    Mark
     
  14. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    I include load calcs and design data on most quotes providing I actually meet and sit with homeowner. That way I have a sense for how serious they are as shoppers. The folks I meet by internet or who wish to send me prints for their 8 sided 5000 SF house "so I can ball park cost of a geo radiant system" simultaneously designing ground loop system......"yeah the other guys wanted to charge me too I just wanted a ball park"......."Around 50 maybe? Well look at the prints and see if that's the ball park......"

    If I have a sense that people would like design work for free so that they may then continue to shop via internet ("guys won't have to ball park it now because I have the heat load calc and design data that joe gave me...." I offer this product for a fee that may be deducted from the purchase of a geo system.
     

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