pond loop efficiency?

Discussion in 'Surface Water Loops' started by meddac, May 22, 2011.

  1. meddac

    meddac New Member

    Hi All,
    I presently have a 5 ton waterfurnace unit in a 1/2 acre (spring fed) pond that is about 8 feet deep where the 1500' feet of coils are placed. I have no problems with the performance of the unit winter or summer but I'm really wondering if my installer should have placed it in my larger pond (3 surface acres about 12 feet deep) though this was about 250 feet from the house vs about 60 feet to the one it's in now. The pond water in the summer gets to be well over 80 degrees even in the deep section. I also have 21 acres and we could have done a ground loop though installation would have been significantly more in where I understand the soil is about 60 degrees year round.
    Your thoughts? I'm thinking I am losing a good bit of the efficiency that I could be having if it was placed elsewhere.
  2. zach

    zach Member Forum Leader


    Where are you located? Closest major city will do. Looking to know if you are heating or cooling dominated.

    Do you monitor your EWT's during the year?

    Are your loops of the slinky/mat style or are they coiled?

    Has your installer measured heat of extraction, heat of rejection or COP?

    Are you satisfined with your utility bills?

  3. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Loops are designed to maintain certain Ewts. With that in mind, no matter where you live or what pond you use, operating cost will be similar. If we have higher average temps, we simply use less loop. Less loop = more efficient loop field (but costs you same to run heat pump).
    i.e. verticals may have half as much pipe in the ground as horizontals, your large pond might only need 2/3rds the loop of the smaller one, but all amount to the same average entering water temperature. Traveling 250' to a pond to use less loops would be self defeating.

    What does improve operating cost is higher entering water temperatures. "a little extra loop" is hardly a blip on the op cost radar. A significant percentage increase in footprint is required (say around 20%) and may cost 3-5 thousand dollars to improve operating cost +/- $100/yr depending on electric cost.

    It is likely the your installer picked the most cost effective plan for you. Enjoy the affordable comfort and savings.
  4. meddac

    meddac New Member

    That pretty much answers my questions. I just kinda worry about the water temperature as there are a lot of fish in the pond but they seem fine. We had a record hot summer last year here in Augusta as 126 days above 90 degrees for the year most about 97. It was 99 today! My electric bill is reasonable...two water heaters 2700 sq ft ranch and everything is electric with 4 people average about 150-200 a month.Keep the thermostat around 75 in summer and 73 in winter. My installer seemed really knowledgeable and did a big computer analysis to include window space, sq footage, orientation of house etc. I really wasn't thinking about how the 250 length would cut down on efficiency but that makes sense.
  5. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Water is the best conductor of heat we have for geoloops, that is why the pondloops have a shorter length than horizontal earthloops. Even your horizontal loop would heat up significantly in the summer time, when you put heat into them. Plus to use the other pond which is further away would mean significantly more pumping power. Chances are that you have to best solution.

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