Open VS Closed?

Discussion in 'Quotes and Proposals' started by PAGeo, Dec 9, 2010.

  1. PAGeo

    PAGeo Member

    We have been in our home for 5 years and every winter we have the same problems that no contractor can fix. We even put in a new heat pump and air handler. So now we are looking into starting from scratch: wells, loops, heat pump, air handler, ducts, everything.

    In your professional opinion, which is better: open loop or closed loop? Which one would you install in your home and why?

    I am looking for the most efficient, highest output, biggest bang for my buck. Thanks in advance for your help.
  2. Looby

    Looby Member Forum Leader

    If those are your ONLY selection criteria, open loop wins.

    OTOH, maintenance-free reliability was high on my list --
    so I went with closed loop (and sacrificed very, very little
    in terms of efficiency or output). pay for what you get,

  3. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    The most effecient bang for your buck would be an open loop that ran on free municipal water and the discharge water just dissappeared:eek:. Seriously the question is a lot more complicated than stated. There is a correct choice for every install and it starts with a qualified installer helping you make the right choice for your specific project. There is a description of the difrances between open and closed loop on our website that could help you get up to speed.
  4. geome

    geome Member Forum Leader

    Same here. I have enough maintenance to do. I didn't want to add open loop to my maintenance list.

    Would a closed horizontal loop work for you? It may be cheaper than vertical loops.
  5. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    I am reluctant to offer advice to fix an undefined "problem".

    That said, open loop "maintenance" could be little or none depending on water quality. I recently replaced a 25 year old system that had nothing done to it but filter replacement.
  6. geome

    geome Member Forum Leader

    Is this typical? Can amount of maintenance be determined ahead of time based on water conditions, or is this a moving target? I knew the maintenance that would be required on our closed loop system before the installation began.
  7. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    It is definately a moving target as aquifer conditions change. Water quality being one of the variables. Some work great for years, others not.
  8. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Just for fun...

    If you tell us why you are not happy, I'll see if it can be fixed.
  9. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Definately a moving target. In my area however there are aquifers where folks do nothing to treat ground water due to it's quality.
    Areas like this may experience no additional maintenance (even after 25 years).
    Even where maintenance is required, it may simply be once a year or less.
    Since geo "is not just for engineers and gadget guys anymore" the more universal consumer is intimidated by the threat of maintenance though it may be minor.
    As there is no harm in closed loop and initial cost may only be a few thousand dollars (depending on size of equipment), I don't tend to fight the trend.
  10. PAGeo

    PAGeo Member

    We have a long history and I have posted here in the past with some of the issues. Basically, we dealt with a company that sold us a replacement heat pump and air handler, but kept the same loop, line set, and ductwork. When it continued to fail, they continued to try different "fixes." None of them worked. Now, we are dealing with a different company and they say that our system is slightly undersized.

    Therefore, we have surmised that we should just start from scratch. So, we are considering open and closed loops. We do have hard water. What kind of maintenance are you talking about with open loops?
  11. Typical maintenance may include flushing the heat exchanger once a year with average water quality here in PA.

    Before you make a decision on open vs. closed loop you will want to know the yield of your well (need 1.5 gpm per ton), conduct a water quality test to compare to manufacturer guidelines, and know the depth of your water to estimate pumping costs.

  12. PAGeo

    PAGeo Member

    What do you all think of this idea:
    New company is suggesting we drill a well and if we hit enough water, then go with open loop. We can use existing house water well as the discharge, once we pull the pump.

    With the research that I have done, it seems that open loops have better heat exchange due to the higher water temps. Plus the WF unit is rated better with open loop. Not to mention the fact that we have had problems with our existing closed loop.
  13. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader


    If you have had trouble with your closed loop system it is not the loops fault. Open loop is Not more efficient than closed loop. The installer can botch up your new plan better than the first plan.

    You need to base your decisions on the guidance and warranty/confidance you have in the installer to stand behind thier design and the performance that they deliver. What if's could continue to infinity.

  14. A new well introduces additional unknowns with water quality and quantity. A good installer can test your existing well and your existing closed loop and make the best decision to either add and balance additional closed loop to meet the load or go with the open loop.

    If you choose open loop and geology and space permits, a horizontal infiltration bed for the return water can usually be added much cheaper than an injection well and may be worth considering.

  15. PAGeo

    PAGeo Member

    Eric, I agree with you on the installer. I believe I have a good installer with plenty of experience, good service, and 10 year warranty from WF.

    You said, "Open loop is Not more efficient than closed loop." Do you mean because of the energy use of the well pump? WF literature states higher EER and COP for open loops. Therefore, I figured it would produce better heat exchange.

    How can we test and know for sure that the existing loop was installed properly, length and grout, and that the grout is still covering 100% of the loop in the well? This could be part of our existing problem, since we have changed almost everything else.

    Adam, we thought of using our existing well, but I don't know if our GPM will be sufficient. One of my concerns with open loop is if the well runs dry or the pump goes out, we lose AC and water in the summer. Heat would be covered by the strip.

    We also talked about a horizontal infiltration bed, but would that really save a lot of $? If we go with open loop, I also want to irrigate with the discharge in the summer.
  16. You would want to first conduct a "pump-test" on your current well. Pumping a specified gpm for 4-8 hrs and recording the drawdown in the well over time. You can then plot this to get a sustained well yield/specific capacity and can calculate if you have enough capacity for the geo and potable uses. Keep in mind that if a well doesn't produce much water---it generally won't absorb much water for injection. Some info on your well including an estimated yield by the driller may be available online at Losing AC in the summer in PA isn't all too bad for most of us here in state but losing water is a pain for sure so I would want to test the well first.

    Horizontal infiltration systems are usually hundreds of dollars to install vs. thousands for a new well but that all depends on the soils/subsurface geology.

    Regarding the evaluation of your exiting closed loop, the performance of any geothermal loop (properly or improperly constructed) can be determined by running a "thermoconductivity test." These tests are normally done on test borings for commercial jobs but the same principle applies for residential. What is typically done is to use a water heater to supply a specified number of BTU's/Hr into a circulating loop and you record the EWT/LWT as the ground absorbs the heat. The same thing can be done in reverse if you already have actual EWT/LWT and gpm data on your loop and can calculate the BTU/hr that your loop is capable of sustaining at an acceptable EWT.

    Last edited: Dec 15, 2010
  17. PAGeo

    PAGeo Member

    I'm not sure if the company we are dealing with can do a thermoconductivity test. In March, we have had EWT as low as 39 degrees and LWT as low as 34 degrees. The split seems to stay around 5 degrees in heating.

    Would we lose or gain anything if we would drill a new well for a closed loop and tie-in the old loop (if there is a problem with the old loop)? Should we just abandon it?
  18. geome

    geome Member Forum Leader

    I still don't understand what the issues or problems are either. Would you please explain more in this thread?

    Also, what's wrong with 39f EWT? This is better than the 36f EWT (that I was thrilled with) for our oversized horizontal loop at the end of our last (brutal) winter in February 2010.
  19. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    I agree
    Lets get this back on track. With an ewt of 39 in march at the end of the heating season a lot of people would give a lot for that number. If it is a question of comfort in the home you may be looking at the wrong side of the puzzle. An ewt of 39 degrees running through your unit will produce X btu's of heat. If you are not comfortable or the unit will not satisfy the t-stat there is something wrong on the house side.
  20. That really isn't a bad EWT since most are designed to go down to about 30F around here. If you need additional ground loop for a larger unit, then there certainly would be a benefit to tying into your existing loop provided that you can do it an balance the flow between the circuits. This can be done using a balancing manifold such as: REHAU NA - PRO-BALANCE<sup>®</sup> Polymer Manifold


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