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  1. #1
    Join Date
    Dec 2009
    Location
    Hotlanta GA.
    Posts
    214

    Old fart learnin geothermal ?????

    From another post I did in another part of this HUGE web site...........
    I figure some one some were will see this and I'll be one smart old fart soon !!!

    Well I have a few years left in the trade and its come to pass I need to upload this geothermal stuff now.............. will be doing a change out for a REALLY special friend!! going closed ground loop............

    So, I understand water source HP, work on them all the time in ceilings and buildings, have read many post here now and have a better understanding of some of the ground points.............

    Few questions to help clear things, how do ya calculate the loop lenth needed?? I see a program out there "Right Loop", but since this will more then likly a one time thing, not wanting to put the money out for ANOTHER program..... Internet is not a place for me to go searching, I'm lucky to find my own house let alone all this stuff on Google !!!

    Some info............ Slinky loop laid flat, location, north GA. ground is * hard dirty !!! Like I'm an earth exspert now !! ????

    Unit will be 5 ton. name brand not made yet.

    I understand the "SAND" lay in thing, as in great contact for the piping, wet it and all that to get the best contact !!! Neat vidio on the net !!!

    Defintly using the slinky rig for building loop, ausome vidio too !!!

    For now I am figuring we will go with an externall pump station in stead of built into unit, comments on that choice would be good............ Too much crap inside those cabnets already !!!

    House has the 5 ton dx split heat pump and does very well, I see mention of duct work issues, is there something I'm missing ??? I figure if ducts are good now, why change, after all, 5 tons is 5 tons.....????

    Good news is I patched his leaking evap coil, and the acid test came back clean, so I am going on a bad factorty coil, 7 years old and already a leak, third row back, 1 inch from u bend joint !!! Frigidair ---- need to stick to refrigerators !! So have time to get up to speed on this stuff, just one more thing to add to my memwars !!!


    Well there ya have it, questions and what evers, hit me now while I go ponder some................

    In advance, I will thank you all for being here, makes an old fart like me feel better knowing I'm not the only one still learning............... be kind !!!

  2. #2
    Join Date
    Mar 2008
    Location
    northern Indiana
    Posts
    114
    Dealers have a program they use for loop length by entering heat loss/gain loop type and soil conditions.
    An accurate heat load is imperative don't size by existing equipment!
    The program will also help size the unit by showing operating cost for different units loop temps and design conditions.
    I assume the extended slinky is what your referring to and I feel it is best.
    External pump is good for reasons you mentioned.
    Heat pumps require more air flow than conventional systems just make sure duct work is adequate well sealed and insulated.
    Proper design and installation will will make for a happy customer and save you a lot of headaches.

  3. #3
    Join Date
    Dec 2009
    Location
    Hotlanta GA.
    Posts
    214
    Thanks, locols reps are not too helpfull on design for loop. The heat pump in place is good, ducts are good, I already had them redi some trunks, given the original installer cut soem corners, new air flow works great, so they say !!!

    Exstended slinky, yes way to go..............

    I have so far this as a base understanding, 600 feet of plactic pipe per ton, with 3 gpm per ton, ground dept will be at least 6 ft. covered with sand and toped with regular ground removed dirt............

    Need to get bettier info on dirt diffrences and depth info..............

    at this point it looks like we have the winter to ponder the job.

    Thinkin we might drill some holes down and place soem temperature probes and bury them, read them over the winter for brain testign !!!

  4. #4
    Join Date
    Mar 2008
    Location
    northern Indiana
    Posts
    114
    Slinky loops are put in a trench around 125ft length for 600ft of pipe (extended slinky). Deeper the better but cost and safety become the issue. The trenches are separated by at least 10ft

    Your looking for soil conditions at depth... heavy - lite - damp - dry- ect. Damp is good... dry clay is not and affects your sizing.
    Temperature readings are for your amusement only not useful.

    Every manufacturer has the software available to dealers if they don't use it I would look elsewhere.

  5. #5
    Join Date
    Sep 2010
    Location
    Dayton, Ohio
    Posts
    119
    We have had all of the calculations done on all of our jobs and we always end up doing the same exact thing every time. We use 600ft of 3/4 geo pipe per ton, 1 1/4 inch supply and return lines to the header, and 5-6 feet deep. I live in Ohio, so this may not be the case everywhere. It is not sandy here, its pretty much clay. We do a min of 100feet on each trench length at 5 feet wide and 10ft in between. We've done quite a few, and they have all worked great.

  6. #6
    Join Date
    Mar 2008
    Location
    northern Indiana
    Posts
    114
    I'm curious 5ft wide trench what or how do you dig that @ 5-6ft deep.
    Most diggers around have around 40 inch buckets.

  7. #7
    Join Date
    Sep 2010
    Location
    Dayton, Ohio
    Posts
    119
    I ment to type 4 feet, but even that was a wrong number. I double checked and it was 40 inches. We measure from the edge of one ditch to the edge of the next, so there is still a 10 foot spacing. So, if you are looking for a 5 foot bucket, I'm wrong... its a 40 inch bucket.

  8. #8
    Join Date
    Sep 2005
    Location
    Atlanta GA area
    Posts
    21,278
    Sounds like a fun project... drop me an Email... John
    GA-HVAC-Tech

    Quality work at a fair price with excellent customer service!

    Romans Ch's 5-6-7-8

    2 Chronicles 7:14

  9. #9
    Join Date
    Apr 2008
    Location
    Pa.
    Posts
    1,078
    maybe best for you to sub out the ground work if you don't have a fushion tool, flush cart ect. these are 2 very pricey items over 2000. We have one local excavator that does geo all the time and use him during our busiest season to help us keep up. Here in NE Pa we do 800 ft of 3/4 pipe @ 100 ft long per ton and 10-15 ft in between trenches about 5-6 ft deep. we avoid using sand and use cracker dust in its place cause that's what our rep suggest to maintain better contact through the expansion and contraction of the piping (valid? I don't know. we just do it). I wish you well on your endevor but it will require a investment of tools and training along with certs to do it properly.

  10. #10
    Join Date
    Dec 2009
    Location
    Hotlanta GA.
    Posts
    214
    OK, now I'm cookin !!! First thing is I need a bigger pot !!! Sooooo much stuff to this dirt cooling !!!

    Fusion (if needed) will be subbed out I am not lookin to be doing more then a few fingered handfull. I am waiting for more from the site down the road from this project location. Thing is I am over 100 miles form site, so its going to be a head full, I am working on getting the customer to slow down and let me get my ducts (or pipes) in order !!

    So far things are only on the plannign stage, he wants to move before end of year for tx credits. He has the trench digging stuff, so cost will be low, finding pipe wil be an issue !!!

    Thanks all for imnput, keep it commin !!

    I truley do appreciate the help.........

  11. #11
    Join Date
    Mar 2008
    Location
    northern Indiana
    Posts
    114
    Pardon my ignorance but.... just what is "cracker dust"?

  12. #12
    Join Date
    Apr 2008
    Location
    Pa.
    Posts
    1,078
    no problem tee. Its like the filings from drilling mud. more course than sand.

  13. #13
    Join Date
    Nov 2005
    Location
    Ontario, Canada
    Posts
    54
    I just went to a dealer training on loop sizing and installation, and they said that slinky loops are mostly pointless, and you'd be saving a lot of time, money, and effort by just installing either a vertical or horizontal straight loop.

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