New to the forum had a question maybe some of you could answer

Discussion in 'Geothermal Loops' started by RyanKearney, Feb 1, 2012.

  1. RyanKearney

    RyanKearney New Member

    Ok, here's the deal. I work for an orchid grower in Georgia. Our biggest customer is Whole Foods Markets which is very big on green energy. For instance, last year I installed solar assisted radiant heating in one of the greenhouses and it's doing just great. Now it's time to think about cooling(the plants need cool nights to produce flowers) and the owner is ready to move. What we are using for cooling is evaporative coolers but the problem is the water reservoirs get hotter than we'd like and that reduces the effectiveness significantly since the outside humidity levels increase along with the Summer heat. Looking for a steady 20 degree drop in this 600 gallon in-ground tank.

    What I was thinking, as he's on city water, is a cold water circulation system using a heat exchanger such as this one. 30-plate Brazed Heat Exchanger (1" MNPT)

    There's approximately 1000 ft between the greenhouse's reservoir and the meter near the road. What I'm proposing is to tee off there or wherever makes the loop length short enough for the pump to handle. I'd have the option of a 2,000 foot loop that gets refreshed with city temp water every time the plants get watered or other major water uses in addition to the earth coupling without pulling any water through the meter.

    Has anyone done anything similar or have any thoughts regarding my current plan?

    Thanks in advance, it's much appreciated.
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader


    I've had similar conceptual thoughts with golf course irrigation and so forth.

    It comes down to run times and so forth. Basically, if you have all day to cool down a tank of water, then you would need a smaller system than if you had to do it in 30minutes.

    So, first figure out your run times. How much sprinkling do you do? What is the flow? Etc...

    This helps you get a grasp of the btu's involved. If, on a project like this, you are out by an order of magnitude it might not make sense to pursue it any further. If you are close, then it may be worth putting it in and seeing how it runs.
  3. RyanKearney

    RyanKearney New Member

    Change of plans

    First off, thank you for the reply. :)

    So we've decided against my first proposal as there is an unused well on the property 175 feet from the reservoir that the evaporative coolers pull off of. The bottom is 45 feet down and the water line is 22 feet from the bottom, so around 500 gallons of a heat sink. I'm thinking of pulling off the bottom of the well and returning it at the top, using a heat exchanger to keep the well water separate as it doesn't play well with the cooler pads.

    My run time would be nearly 24/7 during the peak of Summer. We are using a Little Giant model 8 sump pump to push the water 10 ft to the perforated pipe that keeps the pads wet. Specs say 54 GPM at 5 feet head loss, but I wouldn't know where to start calculating flow for hundreds of 1/16" holes. I had to remove the reservoir liner today as the guy who was their before me really goofed on the install. I can get a better flow measurement sometime next week when it dries out and I can apply a proper sealant.

    I'll let you know when I have some better numbers to work off of. Honestly, anything past a 40,000 BTU per hr subtraction would make this a success.
  4. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Here is a picture

    We built this to take advantage of the BTUH in a spring that provided 24 gph.


    Attached Files:

  5. dgbair

    dgbair Just a hobby Forum Leader

    24 gph

    Hey Mark... just wondering what you were able to do with a flow rate like that.
  6. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    It works,

    but I am clueless as to what the system would do in a maxed out situation. My intention was to test the system and get some numbers. We designed for 4 tons nominal and to provide the continuation of the irrigation provided by the spring.

    I know what a pain it was to remove the perforated copper tubing and replace it with srd11 3/4" HDPE after the tank was in the ground. The water was very aggressive and the copper was imported.

    The tank is a poly septic vault that holds 500 gallons. The four ton water to air system dropped the indoor temps from 85* in less than 10 hours to 70* and raised the tank temp 1*F in that time period. I was not set up for measuring latent heat removal. So I do not have any numbers beyond what I have typed.

    The customer and I agreed to dis-agree, and that was that.
  7. dgbair

    dgbair Just a hobby Forum Leader

    cool ... I'm surprised with just 24 gph there was enough water exchange to keep the tank cool.

    I've been pondering if I could use a dominant hand dug well for a 'cheap' geo system in my workshop... one of these days I'll need to run the numbers and start up a new thread (as I don't want to hijack this one. )

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