Maryland Fix or replace existing geothermal unit?

Discussion in 'Quotes and Proposals' started by tangra, Mar 16, 2016.

  1. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    A fool convinced against his will is of the same option still.

    You only agree with those that mirror your image.

    That make two lectures I await.
     
  2. Yeah that's alot of good insight. But with that huge capital gain, granted it is gain and not overhead, I don't see anything wrong with competition driving down the price of things. Granted too good to be true usally is. Not to offend anyone, seriously, but the cheapest installer may just be a bit more competitive or like you said falty. Let the reviews decide. Everyone deserves a chance. :)
     
  3. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    David:

    I can no longer walk, so I bid this job at 11,000, 10,000 and 9,000. I assumed your help and added a case of beer and two chairs.

    When you are ready to know what it takes to run a business. Let me know.

    Mark
     
  4. I apriciate the offer mark, but it's just simply the wrong time of year for chit chat with a farmer. I have manure truck that need cleaned up for silage, 600 acres of hey down and 1200 more to go in brenueo ground needs planted up north. And a geoexchange pump to be mounted wired and ducted. A flow center to fabricated ( granted if I don't buy one just to save some time). But I'll tell you what, once the snow falls and the freezer is stocked with some fresh elk meat. You hold up your end of the bargin I'll make a trip.
     
  5. Have a thought though, I came acrost the idea of oversized loops a few times on here, and it's often overlooked because of wasted energy pumping the extra fluid. I guess this would only apply to those with indoor manifolds, but what if an aux loop was installed with a back up aux pump to assist thing when demand calls. A few silinoid valves, solid state relays, a pithon script using an arduino and a rasberry pi and it could be fully intigraded. Heck you could even add a few temp sensors and a well Witten program and the computer could controll which loops to use based on efficentcy, and provide real live geographical information on diference loops types in different areas. Just a thought.
     
  6. It would also need a fancy name too, what about active loop management. Now that sounds expensive.
     
  7. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

  8. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    There is no such thing as an oversized loop penalizing your performance. It just cost much more to install, but it does not cost more to operate. But you get to the point of no return.
     
    urthbuoy likes this.
  9. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    David:

    Great title and/or job description. Has to be worth at least an extra $25.00 per hour without training or overhead. I do not do it but I get farming. We will book the work in anti-tractor time.

    We moved to Willard Ohio when I got sick and hurt. Google Celeryville, Ohio.

    Mark
     
  10. That's what I figured, but look around people talk of bigger loops and they get hammered with cost of pumping. Im oviously new here but I would say to someone who wants to oversize a heat pump for a "safty zone" to get your heat load, size your pump correctly and if you got money after that design your loop field larger, when in times of need it can buffer the extra loads with higher efficiency. Do you agree? Like I said if pumping was an issue you and shut off the extra footage.
     
  11. I'll hold up my end, if you do the same. :)
     
  12. Btw, training in the field, or through hard knocks is still training. Lack of common sense dose not last long out here. Good help is so hard to find. It's mother nature that punishes every mistake, brutally also. It's a neverending class room. :)
     
  13. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    You are not saving pumping power by shutting off the extra footage. Your heat pump needs a certain amount of flow, roughly 2.5 -3 gpm per ton, no matter how big the loop field is. The total pumping does not go up with parallel circuits. Putting more loop in you likely loose velocity and turbulent flow, yo will have very low Reynolds numbers. But your surface area will go up due to more pipe, more than compensating for it. So the pumping will get easier with larger loop fields, no need to shut part of them off.
     
  14. That makes perfect sence, not sure what Reynolds means but in context I think it makes sence. So in my install, I'm going to try and cool 2 tons worth of space with a 1 ton heat pump. The digging will be next to nothing or free, and sdr 11 3/4" at only $.19 a foot using a loopfield plenty large for a 2 ton would be benificial. Other than time, the point of diminishing returns should be pretty low, especially if I plan upgrade pump size in the future. As of now I would need 66-70kbtu of heat for down the road. For now I'll stick to natural gas for most of the heat, it will be set up in a dual fuel configuration.
     
  15. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Reynolds number/turbulent flow v laminar flow......layman's:
    Since loop fields came to be, the push has been to minimize their size. This to reduce damage to lawns and minimize material and labor. One tactic is to keep the water mixing up in the pipe (turbulent flow) so that all contacts the walls. Similar to rifled refrigeration tube heat transfer is improved without increasing surface area.
    A misconception in this biz is that one must achieve turbulent flow. Common of book v hands on educated as this is not true if you have enough surface to transfer design btus without turbulent flow. Inversly if troubleshooting a system that is struggling to maintain design extraction/rejection (of btus) ensuring turbulent flow would be one of the steps.
    Type of antifreeze and concentration would impact the "Reynolds Number". A manufacturer's tech rep related the story of an underperforming system that was corrected by changing antifreeze from propyl to methyl vs adding loop as others suggested. Either would have worked, turbulent flow was cheaper. You can easily Google and find the chart and dictionary definition.
    "Diminishing returns" in the context of geo ground loops:
    I believe elsewhere we directed you to CM's Geodesign software. If you have it you can look at the "advantage" of "a little extra loop by changing minimum EWT from the default of 30F to 31, 32 etc.
    For illustration for those who don't have this tool I pulled up a recent design (3 ton unit):
    Design Minimum Temp (F) Feet of loop (3/4", 6 pipe trench) Annual heating cost Horizontal loop field cost (retail around here is about $1.67/ft)/ROI
    30 2970 $534 $4960
    32 3870 $521 $6463/~115yrs
    40 14370 $494 $23,998/~476yrs
    Look at how much extra loop is required (about 2 miles for the 10 degree bump) vs how little is saved on operating cost.
    There is one unevolved installer in NY that boasts not using antifreeze in his systems and another large, high profile project where one of the persons close to the project bragged that they would never vary more than a degree or two from undisturbed ground temp (additional cost on that one is likely 9 figures).
    It may be cheap and easy for you to add extra loop (and I agree if you intend to expand the system best to only dig once. It is not however good advice to my clients.
     
  16. Ok. Thanks, how wide of bucket do you need for a 6 pip trench?
     
  17. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    How wide do you want to put the pipes appart?
     
  18. Not sure, not sure how far the trenches shold be. I assumed 8' deep 6' apart should be okay. I was just going to slinky but if I get a 3' wide bucket maybe a straight shot with more lines would be better.
     
  19. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Sure, you can have a 3" wide trench, 6-8" deep, and run the 3/4" pipe out 300' and come back on the other side of the trench 300', for a total of 600'. So they are 3' apart in the trench.

    Now, how many trenches do you want to do, do you want to cover your whole load of your building?
     
  20. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    All y'all need to quit feeding the troll.
     

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