Open Loop Pond, Gravity Flow

Discussion in 'General Discussions' started by Eric Kurtz, Jul 23, 2018.

  1. Eric Kurtz

    Eric Kurtz Member

    Hi to all,
    I have an idea for using an open loop which would be gravity fed from a pond to our new (last fall) modular house. I searched for info online, and what I found on this forum seemed great, so I'm going to lay out my proposal to you all and see what I can learn.
    First of all, a bit of my background, I work for a dairy equipment service company, so am quite familiar with electrical, plumbing and control. I also service bulk tank refrigeration, so have a good grasp on the refrigeration, as well. And I love figuring out how to do something, then doing it myself whenever feasible.
    So here goes.....
    The house
    1400 sq ft with full basement, R 19 in walls. R38 in ceiling, Basement is ICF foam (2.625") forms with 6" of concrete.
    8' x 10' garage door in basement R18,
    The current furnace.
    Electric resistance forced air, 2 10,000 watt elements insulated 6 x 18 ductwork in basement (planning to go all new ducts). Also have wood stove in basement. Last winter burnt 3-4 cord of wood highest electric bill was $200.
    Pond is an old entrance to a strip mine cut. Approx. 1-1.5 acre. 8' deep at deepest but large portion is between 5' and 6'. Pond surface is 11' higher than basement floor and 200' away w/100 ' more to get to deepest part. It gets very little run off, but pumps out 20 to 30 gpm year around.

    Basic plan
    Run 1.5" (?) pipe from deepest part of pond to house Downsize to 1.25" and run to heat pump (2.5 ton?). Dump water down 2" drain in basement floor. Stay warm and cozy all winter long without having to run wood stove (although I probably still will) :)
    That's the basics.
    A few questions and comments that I have, then I can't wait to hear yours!
    I will need to run a manual J to size for sure. Played with an online calculator some but has been a while.
    I will need some help with duct sizing and maybe install. Thought about finding a local HVAC guy to help design that part
    I would like to have 3 zones. 1 for basement garage, 1 for rest of basement, and then 1 for the upstairs.
    Do I need a pump or will gravity @ 10'of head provide enough flow?
    What size of pipe? according to a chart I found online. 1" technically would have just enough flow, but i'm sure friction loss would be too high. But neither do I want to go too large and loose velocity which could cause buildup in pipe.
    Last but not least, I do have a well with plenty of water that is 75' deep as backup, BUT pond has better water than my well! See attached reports.

    Attached Files:

  2. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Hi and welcome!
    Running a raw water system out of a pond will net problems with the biologic activity and where is the suction. The last thing you want in the dead of winter is a suction line fouled with algae or a turtle or frogs or a dead duck or goose. Solve that issue and it is a go. The other concern is if the pond ever freezes? What is the temp of the water feeding the cut? That will help you determine what your projected operating range. You will prolly need a pump. Depending on the entering water temp in winter the consumption could be as little 6gpm or as high as 9 gpm. Water needs to move with flow not high pressure.
    Hope this helps
  3. Eric Kurtz

    Eric Kurtz Member

    From what I've learned, water temp shouldn't drop below 39. How much will it drop going thru the heat pump is what I don't know? As far as plugging the line, an intake screen with a black bucket inverted to keep any light from getting to it should take care of that. The water is clear to almost 6' deep. I also thought of using a plastic 55 gal barrel as a sediment team in the line. Although I don't really think it is necessary.
  4. nc73

    nc73 Member Forum Leader

    Stop playing around and go closed loop. Put pipes in the pond, circ pump and quit dicking around. :) Your idea is high maintenance.
  5. Eric Kurtz

    Eric Kurtz Member

    Can someone please explain this biologic activity thing? I assume it means algae and bacteria getting into your heat exchanger and plugging it. Does anyone have an open loop that uses raw surface water? If so, how do you deal with the biologic problem? I'm not dead set on this way of doing it, but my pond runs the water down the creek all year long anyway. If we could utilize this water, it would make for a very environmentally friendly setup. As noted before the pond is very clear and the water test show less dissolved solids than my well water. My raw well water is not a good option for 100% use due to test results. However it would make a good backup system. The well produces plenty of water. 75' deep but water level is at 18'. Driller bailed as fast as he could (30 gpm) and only dropped level 7 '. So that is not a problem.
  6. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    You are asking for trouble with an open pond loop. Put pipes in for the heat exchange. Your heat exchanger will plug.
  7. Eric Kurtz

    Eric Kurtz Member

    Ok, between the blunt advice and my own research, I am abandoning the whole open loop idea. The pond may/will plug the heat exchanger but even worse is that the temp will drop too low in winter to use without blending with my well water, and my well quality is marginal at best. Plus, the whole pumping water out of the ground doesn't appeal much. So that leaves me with a horizontal closed loop setup since my pond is really not deep enough (6' with only a small portion at 8'). Will start a new thread for the closed loop build. Thanks to all.
  8. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Who says that a 6-8' deep pond is not deep enough? Is the bottom of the pond frozen solid in the winter? 8' this ice? If not, obviously then there is warmer than 32F water down there....What size is your pond?

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