Geothermal heat pump that dumps back into well

Discussion in 'Open Loop' started by GEM, May 8, 2012.

  1. GEM

    GEM New Member

    I purchased a new home around 6 months ago, right at the end of summer. Through winter, my electrical bills were sky high. About a month ago I turned on the AC for the first time. After a day I noticed that the cold water coming from my tap...was no longer cold. It was hot in fact. After much trouble shooting I discovered that the geothermal system at my house pumps up from my well and dumps back into the very same well. From everything I can tell this is not the way geothermal is supposed to be set up. What steps do I need to take to fix my system? What is more effective a dry well or a pond. Adjacent to my home is an empty lot with a well. Should I purchase the lot and use that well as a dump? How much does a dry well cost? How large of a dry well do I need? Should I just pull out the geothermal and put in a conventional HVAC?
  2. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Hi and welcome,

    What you have is two very distinct problems.
    1. sky high electric bills in winter could be a plethra of issues. The easiest to fix would be a thermostat that is running stage 3 heat all the time. A more serious cause may be the design load is not correct.

    2. What you have is called a standing column well. When designed correctly they work as well as any gethermal system. Hot water in your cold water tap is indicitive of the temprature bleed off valve is malfunctioning, or maybe you don't even have one.

    Find a geo pro in your area and start peeling back the layers and you will start to understand and get answers.

    Hope this helps.
  3. zacmobile

    zacmobile Guest

    What exactly is that? I don't think I've ever heard that term before.
  4. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Typically in a standing colunm well, there is a temprature actuated soleniod valve that opens to bleed water out of the well if it gets to hot or to cold for the geo unit to be efficeint.
  5. Calladrilling

    Calladrilling Member Industry Professional Forum Leader

    Never worked on a SCW before, but I always wondered how it didn't heat the water up over time no matter who deep the well was. I figured it had to have some kind of bleeder valve to introduce cold/fresh water into the well.
  6. GEM

    GEM New Member

    I am sure there is no bleed off valve. I've had the company that installed it out to take a look at it and they had no clue why my well water is hot. I might have to look to surrounding towns to get someone that knows what they are doing. I'm not sure my well is deep enough to be a standing column well. My well is only 120 feet deep and the water level is at 80 feet. The bore of the well is about 6 inches across. How does one go about installing a bleed off valve?

    In regards to the sky high electric bills in the winter. I installed a new thermostat around 2 months ago. The bills have been lower, but winter also ended, so I'm not sure if it is the thermostat or the ambient temp. The thermostat allows for when the auxiliary heat kicks in. Is there recommended settings for when the aux heat should kick in? It allows for outside temp having to be below a certain temp before aux heat is used. It also has a learning mode were it learns when it would take too long for your home to get warm without aux heat.
  7. GEM

    GEM New Member

    My pump in my well is a variable speed (continuous pressure) pump. That means that when I need water the pump runs. So any time the heater runs the well pump runs. Is that OK or is there a better option for supply water to a geothermal system?
  8. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader


    That is a very short well column to be considered a SCW. Very short.

    Confirmed by the fact it was warm after only one day of cooling. You'd have issues after 1 day if heating apmost likely as well.

    Switching it to a pump and dump may be the most direct solution. Or a 100% bleed valve if I was just being smart @$$:)

    Thatfix should be the focus first.
  9. Calladrilling

    Calladrilling Member Industry Professional Forum Leader

    Gem. You have the best option for pumping. Variable speed pumps are Taylor made for open loop geothermal.
    The best I've used and experienced are the Grundfos SQE line of pumps.

    You absolutely need some way to introduce new cold water into the well somehow or you WILL continue to heat the water up and will drastically shorten the life span of your pumping equipment, as well as have a very inefficient heat pump.
    I have never personally worked on this type of system but I have read that you should at least a 10% bleed off. Maybe somebody else on here has more knowledge but you can temporarily reroute your dump ( return) lines somewhere to see how it performs with cool water being used instead of hot water.
  10. Blake Clark

    Blake Clark Member

    Do I understand that you only have 40 feet of water in your well? No easy way to say it - that's not going to work, nor has it ever worked.

    I have a standing column well 395 feet deep with the water table at around 100 feet. That's 295 feet of water for a 3 ton two stage system. (in cooling mode, second stage is (cleverly) locked out, so its 2 tons cooling) Depending on geology, you need roughly 100 feet of water per ton capacity.Best practices for standing column are a temperature dependent 10% bleed. A lower and upper EWT are set and the bleed valve is activated if those are exceeded.

    With my setup, domestic water use from the same well represents about a 5% daily "bleed" so I didn't bother with the automatic bleed valve. Worst case scenario, I'd turn on a sink tap for an hour or two, but I haven't had to do that. Dead of winter, running continuously, my EWT will drop to 39 overnight but will perk back up to 42 after morning showers and coffee and, um, recycling the coffee... In summer, the highest EWT recorded has been 62, and that was after a week long record heat wave. For reference, in my part of the country deep ground temperature is about 47.

    If your well has the capacity and you've got a place to put the water, "pump and dump" shouldn't be too hard to retrofit to your existing system. Rather than recycling the well water, it is discharged on the surface. I wouldn't drill a re-injection well, though. If that was your only option, I'd instead pay to add a few hundred feet of depth to your existing well and stick with standing column.
    Last edited: May 11, 2012
  11. GEM

    GEM New Member

    Sounds like I need to pump and dump. I have a FHP Model GS048-1VTN, and heater model HP100-1XM. My flow rate can be adjusted from 8 to 20 gpm. I notice it works best around 12-15 gpm. On the worst days of winter and the worst days of summer it runs 20 hours in a day (fortunately usually much less). The soil around my house is a silty loam ( farm land soil it used to be a wheat field). The soil absorbs water well but can become saturated or erode if flow is too fast). How do I design my a dry well? How large does it need to be?
  12. Calladrilling

    Calladrilling Member Industry Professional Forum Leader

    Have a 2nd well drilled to dump the water drawn from well #1 back into.
    We drill them minimum 50' apart.
  13. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Where you are located is the crux of how you address this problem. Step one is verify your data.

    1. does your heat pump water really go back into your supply well?

    2. where is the original installer on this project?

    3. what are the regulations governing geothermal discharge on the piece of dirt where you are

    4. I am not trying to discourage you from diy efforts but this is prolly not something you can sort out alone over the intranet without a onsite pro from your area.

  14. Blake Clark

    Blake Clark Member

    I echo Eric's points and bring up one more. Pump and dump with a return/dry well is not a fool-proof solution. The increased load on your supply well can change water quality for the worse. It is also possible that the return well can get fowled or otherwise not be able to accept the volume of water over time. I'm not saying it can't be done - it's done all the time - only that this solution presents its own engineering challenges. A more cost-effective solution may still be to deepen your existing well and stick with standing column.
  15. GEM

    GEM New Member

    1. It is confirmed that my heat pump water drains directly back into my well.
    2. I had the original installer back out to my house...and according to them everything is fine and they tried to pass off the hot water in the cold water taps as something wrong with internal plumbing.
    3. Dept of ecology allows for dry wells on my property and surprisingly will allow me to dump back into a well. There is no creek or body of water near enough for me to dump into.
    4. Your right I might need to get a pro onsite. the nearest pros have to drive over an hour to get to my house and charge for the trip to and from
  16. Calladrilling

    Calladrilling Member Industry Professional Forum Leader

    If your property is large enough and have the area to drill then I suggest a new well be drilled. If you existing well can produce enough water to the house and geo unit, then I recommend a second well be drilled for the return water from geo to be dumped into. You will have a consistent temp for the geo, and have no worries of bleed valves, or pump over heating.
  17. Rig 40

    Rig 40 New Member


    If it is available, perhaps you could post some info or a copy of the well report for some of the drillers on here to be able to guide you with some options. For example is the hole in solid rock or in some kind of alluvial or unconsolidated formation. May offer some kinds of alternate solutions.
  18. GEM

    GEM New Member

    0 to 82 feet is loess soil, 82 to 84 feet is blue clay. 84 to 111 feet is cementing gravel. 111 to 120 feet is caving gravel. Static water level is 84 feet. There is 45 perfs from 91 to 111 feet. The depth of the completed well is 111 feet. There well has 6 inch diameter all the way down. The well was tested to produce 30 gpm for 1 hour at 100 feet without any drop in water level.
  19. Rig 40

    Rig 40 New Member

    Just an fyi but often deq defines dry wells a variety of ways. Not just a water well with no water. With the info supplied I have to agree with calladrilling in that a second hole would be a prudent and not overly expensive solution PROVIDED the state allow an injection
  20. GEM

    GEM New Member

    Based off of the information above, how deep would I need to have the injection well dug? I have a well drilling company willing to drill a second well, but they have no idea how to calculate how deep an injection well needs to be.

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