Can I use a pond loop

Discussion in 'General Discussions' started by pegleg, Mar 1, 2011.

  1. pegleg

    pegleg New Member

    I am new to this site. I need advise on installing Geo Heating and Cooling. I have a pond that is 250 feet from my house 325 feet to the center of pond from house. The pond is 25yrs old. When it was dug originally it was 16 feet deep with water level around 14 to15 feet deep. Now it averages 10 to 12 feet deep and is maintainning that level except during dry spells. This year being one of them dry spells. It was down 2 feet as of last fall. It has come back up some because of winter snow and rain.
    The contractor that dug the pond told me it would be consider a half acre pond (small half acre).
    I have had 3
    contractors give estimates on installing Waterfurnace Geo systems. they all vary on how they would install the loops.
    1st contractor said he would not advise using pond said it was not big enough. He would install ground loops with backhoe tearring up most of my backyard with 3 different loop fields.
    2nd contractor wants to use a pond loop and also use the 250 ft trenche as part of the system.
    3rd contractor would use what is called a directional horizontal bore machine installing 3 seperate horizontal loops in the ground of at least 150 to 200 feet apiece. these contractors come highly recommended from their respective customers. My question is, Which loop would be avisiable to use. Any help would be greatly appeciated. Also my house is 1900 square feet one level.
  2. Your pond is large enough/deep enough but is at definitely at the far end in terms of distance from your house but again will work. Mark Custis (on this site) is a great pond geothermal resource in your area.

  3. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Any loop is good as long as it brings the Entering Water Temperature within the operating range of the heatpump.

    It depends what the contractor has, a guy with directional boring equipment will rather use that. You pond is on the far end, by the time you have a header pipe out there and back you might not need much loop anymore. You might need more pumping power, I take it that you need 3 ton of loop capacity,so it is not to much of an issue. Make sure you have a pressure drop analysis done before a decision is made.

    At the end it should be the contractors decision, he has to guarantee the performance.
  4. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    " It was down 2 feet as of last fall. It has come back up some because of winter snow and rain."
    This pond would not have cooled your home last summer. I would not use it without modifications that will likely cost as much as more reliable horizontal loops.
    Directional boring generally costs more, while horizontal excavation requires more lawn repair. Which would you rather spend your bucks on?
  5. pegleg

    pegleg New Member

    What is a pressure drop analysis and how is it done?
  6. pegleg

    pegleg New Member

    Are you talking about using the length of the run to pond as part of the system along with the pond loop? The contractor did say something about having to figure out something in reference of using the two together. At the time he didn't go into detail. He must have been refering to the pressure drop of which is talk about in a later thread.??
  7. pegleg

    pegleg New Member

    Why do you say that?

    About the not cooling last summer ? Do you think it will take care of my heating requirements? Like I said I am a novice on this and do appreciate the info
  8. MQuay likes 10-12 ft depth and says 10-50 tons per acre. Climatemaster is less conservative with 8' deep ponds being fine. Rule of thumb often used is 8-10' in depth and 1/2 acre is min pond size. In NW Ohio, I'd be surprised if your pond doesn't have a direct hydraulic connection to the shallow water table which should keep your temperatures much more stable and allow your pond to function better than its size indicates. You can find this out by installing piezometers in the bottom of the pond or taking some temperature readings in the summer and comparing to the groundwater temperature.

    I wouldn't recommend it without modeling, but of course in IN they have 1500 tons in a 12 acre lake: Water Energy Analysis Program

  9. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    "About the not cooling last summer ? Do you think it will take care of my heating requirements? Like I said I am a novice on this and do appreciate the info"

    2' of water won't heat or cool for long. Nor would it have been that deep if you were trying to cool with it.
    I would not approach this design with a "yeah but the pond always fills back-up" attitude unless you are content to have your system out of service until it does.
  10. zach

    zach Member Forum Leader

    Is clarification needed here?

    The pond is down 2 feet from it's normal level of 10-12 feet meaning during a dry spell the owner still has 8-10 feet of water in his smallish half acre pond? This is the meaning I took, not that the level was now at 2'.

    Do we have enough information to know if the pond can handle the load?

    Are we talking 3t of ghp or 6? What is the heating and cooling load?

    Bottom line, what are we asking of the pond to provide?

    From my successful pond loop install I will speak to the fact finding an installer comfortable using a pond is challenging.

    Mark Custis is a resource for you in Ohio.
    Last edited: Mar 4, 2011
  11. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    You nailed it Zach, I was reading it as down- to - 2 feet, which I see is not the case.
    That said, I still would not be a fan of a 250' commute to the pond for the brine.
    I also would suggest that if it hasn't been done, someone should verify depth as another contributor here found out his pond backfilled some (unbeknownst to him) and was inadequate to support his heat pump.
  12. pegleg

    pegleg New Member

    Regarding depth of pond (pegleg

    The pond was originally 16 feet deep when first dug, now 25 years later it average depth is around 12 feet. during droughts it has drop up to 2feet giving me a 10 foot depth. My main concern is using the pond which like I discuss is about 250 ft. away from house. The contractor who wants to use pond said it was ok (distance). I ask him about using the distance from house as an added gound loop in conjunction with the pond loop. At the time I posed this question I don't believe he was thinking about usilng the distance to house as an added ground loop along with the pond loop. the house will require a 3 ton to 3 and a half ton unit.
  13. zach

    zach Member Forum Leader


    To be clear, I am not a pro, just an educated and experienced homeowner.

    The issue of pond to house distance has been raised: The concern would be how much pumping power is needed relative to keeping a Reynolds number (turbulent v. laminar flow) above 2500. Pipe size and distance tell the tale here. Meaning your design.

    My pond is 215 feet to the house. I use a pair of Grundfos 26-99's housed in a QT non-pressurized flow center.

    Botttom line is you want your contractor to show you a pressure drop calculation noting the pumping power needed. There is simple software which makes this calculation.

    The future is in ECM drive pumps, see here:
    Phoenix Flow Centers

    I believe using the house to pond trench could support transport piping as well as an additional ground loop. You are digging there anyway.

    At 3 to 3.5 tons you are not asklng alot of your pond in my novice but experienced opinion.

    I agree with others, you need to be sure the pond has the needed depth. Ponds have been called "black art" but I think 8-10 feet gets you there according to what I have read. Then again, I am not the guy guaranteeing the design.

    I've attached a document from Waterfurnace which details pond loop installation.

    Attached Files:

    Last edited: Mar 5, 2011
  14. pegleg

    pegleg New Member

    Starting over with my question on installing Geo loops

    :rolleyes:So sorry for the lack of info on my part Let me try and give it now.
    1. I have 3 contractors giving me 3 different approaches on installing the loops for my soon to be Geo heat & cooling.
    1a. horiziontal directional boring of loops.(ground loops )
    1b trenching of loops in ground ( tearing up most of back yard) (ground loops)
    1c trenching from house to pond & installing pond loop system.
    The contractor who wants to use pond see no problem with its use even though the loops will be almost 350 feet (counting the distance of loops) from house by the time loop is installed in said pond.
    pond average depth is at 12 to 13 feet during normal conditions. It drops during droughts and also during summer months 1 to 2 feet on average depending on conditions at the time, nothing unusal for the summer leaving a 10 ft depth average give or take
    the pond is consider a small 1/2 acre.
    My question is whats the best way to achieve the best all around efficeicney on energy saving( as far as opperating cost and so forth to heat and cool home (1900sq ft. one story ranch style home.)
    The system will have to support a 3 ton to 3 and half ton unit.
    I ask the contractor, that since the run would be quite long could we use the run itself as part of the loop system along with the pond loop. He thought that was doeable but would have to run some calculatiions. we havent talk again yet
    One of the others contractors said he would use Directional horizontal boring to install just a close ground loop system.
    And finally the 3rd contractor would use the trench system to install a ground loop system .
    The contractor that would install the pond loop along with the ground loop to the home was the least expensive of the 3 bids by about $1400 along with a 50 gal wh for hot water storage.
    I dont mind if I have to pay a little more up front to get the best results later, but I am not rich by any means, My wife an I live on a fix income. I am going with geo heat because of the benefits of the savings long term. I cannot really afford to go back and correct a mistake later in the game.
    So thank you now upfront for your insights on this matter
  15. zach

    zach Member Forum Leader


    From my perspecitve your install is going to distill down to which contractor you are most comfortable with.

    You are given three designs. Which contractor are you most comfortable with? Who is going to guarantee you an agreed upon performance level?

    Impossible to give that type advice over the net. Nothing trumps boots on the ground with a performance guarantee.

    You need to ask yourself these questions:

    who am I most comfortable with?
    Am I OK with my yard being torn up whether pond or horizontal install?
    Who is going to guarantee me a result?

    Ask for references.
  16. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    If you live near or in

    the Black Swamp the pond should be full today.

    I think the pond will work fine for heating and cooling. I would do what we did at Zach's. I might have time to look tomorrow.

    Attached Files:

    Last edited: Mar 5, 2011
  17. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    Be sure and ask for references from each contractor and check them out.

    The contractor that has the most experience and best references is the one you should consider most.
  18. pegleg

    pegleg New Member

    Black swamp pond

    You are right about pond, it is close to being full again.
  19. pegleg

    pegleg New Member

    Thats is a house?

    Thats not a house the a castle. (wow) I couldn't afford to heat that even with Geo themal
  20. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I do not pick the size

    of my projects. I just design and build stuff that works. I wanted to show with that photo how far the pond is from the house.

    The distance at that job is well over 200 feet. To a point the transportation piping can add to your heat harvest, but I do not like to include it. I just take it as a bonus. Here a shot of us building the loops.

    Attached Files:

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