Deepening well to install geothermal system

Discussion in 'Solar and Geothermal Water Heating Forum' started by Twotone, Sep 7, 2018.

  1. Reach4

    Reach4 Well-Known Member

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  2. Twotone

    Twotone New Member

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    Thanks for the education. I had planned to limit the flow through the heat pump to 6-8 gpm with a Dole valve. Minimum flow through the heat pump is 1.5 gpm/ton. A 4 ton unit would require a minimum of 6 gpm. Recommended range is 6 to 8 gpm. Depending on what the deepened well tests out at, should I limit the flow to the minimum to save pump energy?

    The driller is telling me he is required to case the deepened well top to bottom. I am assuming this means (need to find out) the 110' in the old casing would be blocked. The water quality at 110' is 18 grains hardness. 2.5 Iron. Not the best for geothermal equipment. Water quality at 460' near me is 3-4 grains and 0.5 to 1.0 iron. Thanks again for the education.
     
  3. Twotone

    Twotone New Member

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    Valveman,
    How would I determine the minimum pressure required or recommended for a geothermal heat pump.
    The online installation manuals do not cover this.
    They do cover the pressure drop. Ground water temperature is ~55F.
    upload_2018-12-1_0-12-12.png
    I'm asking in reference to sizing the sub pump. Would I size it for 20 psi or would 15 psi work for this model?
    Is there a pump model that would produce 15 psi set at 470 ft?
     
  4. valveman

    valveman Cary Austin Staff Member

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    Sorry I missed this. I normally use 20 PSI to make up for any losses in the heat pump. And yes you can size a pump to fit.
     
  5. Twotone

    Twotone New Member

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    Thanks, I put the project on hold over the winter. I'm on old Coal reclaim land and the drilling rig would rut and sink in the yard during the wet months in Ohio. The bottom of my hill side is still oozing/flowing water. The plan is to start the well deepening in late April. I did upsize the wiring over the winter from the breaker box to the local disconnect in the garage. I installed the cycle sensor. I just hand dug up around the well along the buried 12/2 with ground. It was buried shallow at first and then deep. Part of the shallow was in left over 1" black water hose. Eventually it got deep enough to be alongside the 1' black water hose supplying the water from the pitless adapter to the hold tank in garage. About 15 foot from the well head both went into a 4" heavy wall white pvc pipe. After digging out the wet clay around the end of the pipe and chipping out 6" inches of hydraulic cement, removing a wad of crumpled visqueen and a water bottle, rocks and other debis I was able to get a fish tape through from the basement garage wall to the end of the pipe. I put 1" grey pvc conduit from the 4" pvc to the well head. I need to reseal (old seal was starting to seep into the basement during heavy rains) where the 1" water hose pipe and the 1" conduit go into the 4" pipe.

    My thoughts are to clean the conduit and hose pipe and end of the 4" with pvc cleaner and seal with good stuff spray foam. Then put a 40# bag of sodium bentonite clay (kitty litter) around the end of the 4" pipe then cover.
     
  6. Twotone

    Twotone New Member

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    Cleaned the conduit, hose pipe and end of the 4" with PVC cleaner and sealed with spray foam. Added a 40# bag of sodium bentonite clay around the end of the 4" pipe and covered. No leaks into the basement after 2 rains. I'll monitor after heavy spring rains.
     
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  7. Twotone

    Twotone New Member

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    Driller came out for site survey and go over estimate yesterday. Estimate included a Goulds 7G10422 pump. Pump will be pumping 6 GPM through a Dole valve through the heat pump into hold tank or to tile field. Otherwise it will be off. Is there a more efficient pump brand at this flow?
     
  8. Reach4

    Reach4 Well-Known Member

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    If you think the pump may sometimes draw down to near 470 ft, that seems like a good choice.

    If your geothermal system puts the used water back into the well, the pump would not draw down much, and you could reconsider different pump.
     
  9. Twotone

    Twotone New Member

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    Thanks for the input. Ohio does not allow you to put used water back into the well.
     
  10. Twotone

    Twotone New Member

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    The driller started on Monday the 17th. Sometime between 1990 and 2007 the well had been deepened but no log was filed with ODNR. The original driller now works for the drilling company I hired. The owner called him and he indicated the original drilling company didn't do the deepening. The deepened well was producing less than a gallon a minute. The original 1999 1 HP 10 gpm Franklin pump was in the well. The driller will give me the as found and current conditions tomorrow. I spoke with the service guy who was cleaning up when I awoke. I'm working midnight shift this week.
    He said the hole is punched, casing installed and preliminary test filled a 5 gallon bucket in 45 seconds. Calculates to ~ 6 ⅔ gpm. He didn't know the final bore/casing depth or the depth pump would be set at or the drawdown level. He did know it was under 500 foot. I'll ask the owner/ driller. He said they may not come back to site until Thursday. I'll update as time permits. I'm hopeful that the well test final numbers will improve a bit.
     
  11. Twotone

    Twotone New Member

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    The well is completed. 478 ft depth, pre-pumping static level 275 ft. Water encountered at 398-418 ft & 465 ft. Test rate 17 gpm. 1 hr. 105 feet of drawdown. Sustainable yield 17 gpm. Pump set at 415 ft. Goulds 7G10 with 1 HP Franklin motor. No noticeable drawdown at 6 gpm.

    With pumping through the geothermal coil into the storage tank:
    Geothermal unit is set and duct tied in. Driller has storage tank full of fresh water.
    I am now on days and will be running the piping and field tile lines on afternoon/evenings.

    Valveman

    Control questions:
    If the storage tank is full and geothermal running, the cla-valve would dump to the field tile line.

    If the storage tank is full and geothermal has shutdown, what would be the most economical way to control the well pump?
    I have a cycle sensor mounted at the well local shutoff.

    I would need to put a shutoff valve on the storage tank inlet and control it with the existing level float. Recommendations on valve?

    If I put the existing taco valve on the field tile line I would need a pressure switch to shut down the well pump. Will it chatter?
    Or would the cycle sensor take it out? Or is there a better way?

    Thanks for the advice thus far.
     
  12. valveman

    valveman Cary Austin Staff Member

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    From 275' a 7GS10 will pump 10 GPM. From 380' it will pump 8 GPM. I don't see needing valve on the well pump at all. Just tie the well pump to the heat pump controller. Heat pump on equals well pump on. If you don't want it pumping 8-10 GPM just use a ball valve adjust the flow as needed.
     
  13. Twotone

    Twotone New Member

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    I ran the installed pump 7G10 (not a GS) into a 5 gallon bucket with a stopwatch. It is pumping ~7 gpm. Ran it for 30 minutes with no change in the flow. The storage tank has a level float switch and is located in the garage. I was wanting to prevent it from overflowing. My thoughts were to put a shutoff valve on the line coming from the heat pump coils to the storage tank and tie it to the to the storage tank level switch. I don't think it will go empty shutting well pump down the well pump from the heat pump controller. I plan to install a cla-valve on the field tile line that is teed into the same well pump line.

    Tell me what you think.

    Thanks as always
     
  14. valveman

    valveman Cary Austin Staff Member

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    Maybe I don't understand. If the heat pump is going to use 6-7 GPM, and your well pumps produces 7 GPM, then the well pump will be running the same time as the heat pump. That water has got to go somewhere. I am not worried about the storage tank being empty. I think it will stay full and overflow all the time. If that is the case you don't need a float switch, cla-val, ball valve or anything. Just relay the well pump to come on with the heat pump, and pipe away the overflow from the storage tank. Your booster pump and house would have to use a lot of water to keep the storage tank from overflowing.
     
  15. Twotone

    Twotone New Member

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    The tank is in the basement garage at the front edge of the house closest to the well. The house is on a steep sloping lot, sloping downward towards the front of the house. In the current position the storage tank would overflow out the top and flood the basement garage floor.

    To go with the scheme above I would need to relocate the storage tank and pump 75 feet to the downhill wall and pipe back to the house header.
    The piping is a wash as I was going to pipe the well to the unit and back to the storage tank and tee at the unit and dump the cla valve at the downhill wall.

    Sometime you can't see the forest for the trees. Thanks.

    upload_2019-6-24_21-4-43.png
     
  16. Twotone

    Twotone New Member

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    I have a problem with the storage tank booster pump rapidly short cycling. I checked the bladder by depressing the valve core in the top of the tank. All air. I drained the pressure tank. At the end of the draining air came out of the tank. I thought it may have been water logged. I checked the bladder pressure of the empty tank. 28 psi. The pressure switch is a 50/30 Square D model. I refilled the tank. Same rapid short clycling. I drained the thank and checked the sensing line from the booster pump head to the pressure switch. The pump head pressure tap was mostly plugged. I cleaned it out. I blew out the sensing line. I looked into the pressure switch and a lot of sand. I took the pressure switch apart and cleaned it out.
    After turning the pump on, it built pressure to 50 psi and went to rapid cycling. I had a used 50/30 pressure switch so I drained the tank and swaped it out. Rapid short cycle. I then drained the tank and took both pressue switches apart, counting the turns on both screws. I filed the arced point faces flat and re assembled. Same problem with rapid short cycling. The sensing line now has a slow drip from taking it apart so much. I purchaced and nstalled a new pressure switch and sensing line. Same rapid short cycling. The booster pump has a 44 gal Well Rite WR140R bladder tank. The new pressure switch is currently set at on at 30 psi and off at 50 psi. Am I missing somthing? Is this a motor problem?
     
  17. valveman

    valveman Cary Austin Staff Member

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    There is nothing wrong with the switch. Rapid cycling means your switch is too far from the pressure tank, or you have an un-needed check valve between the pump/switch and tank.
     
  18. Twotone

    Twotone New Member

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    Here is a photo of the existing system.
     

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  19. Twotone

    Twotone New Member

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  20. Twotone

    Twotone New Member

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    Another one
     

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