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open loop geotherm question

we have a customer with an open geotherm system. the water is pumped from the same well that supplies domestic water to the home. the water goes through one six ton heat pump unit, and then gets dumped into a field in the back of the property. this is older home, and this system has been grandfathered in to the new local ordinances. there is a testable backflow preventer where the water enters the heat pump unit. is there any reason that this water that goes to the heat pump unit, go through the water softener first? the customer goes through a ton of softener tablets through the year,and would like to install a bypass line around the softener to the heat pump unit. I am unsure if this would create more problems then it is worth, if the raw ground water fouls the tubes of the heat pump unit. the only suggestion i would have would be to install the bypass line, and keep an eye on the ph level to ensure it stays between 7-9 going to and from the heat pump unit. these systems are very rare around here so any suggestions would be much appreciated. thanks to all


  • SWEI
    SWEI Member Posts: 7,356
    Water chemistry depending, probably...

    If the only major issue is hardness, then your assumptions are most likely correct.  Should that be the case, A couple of hose bibs and 3-way valves and some simple routine maintenance can easily resolve the issue.
  • icesailor
    icesailor Member Posts: 7,265
    Well water chemistry:

    It is my long experience that if you don't understand well water chemistry, and you try to fix it, the laws of unintended consequences really come in to play. That no good deed will remain unpunished. If you have a problem with one thing and you fix it, it will cause something else to become a bigger problem which will require an expensive fix.

    PH isn't the only problem to be aware of. TDS (Total Dissolved Solids) and what form is a bigger concern. If you are using a water softener to get rid of TDS, and iron is present, it is a form of hardness which water softeners will remove "reasonable" amount of. But if the PH is low, like below 6.7. the water softener doesn't work as well so you need to correct the PH by adding hardness to the water so the softener can take it out. There are other ways of getting iron out of water. All difficult and expensive. And if you run the raw water through the HX and it starts to settle on the coils, it can foul the HX to the point of it being useless. Put a pan of unfiltered cold water on a stove and boil the water away. If there's a lot of white crud, start thinking about the unintended consequences.
  • icesailor
    icesailor Member Posts: 7,265
    Softener Backwash Drain:

    Look at the water softener back wash drain. The drain usually is a 1/2" hose that you can remove with a screwdriver and pull it out. There will be a rubber orifice inside that controls the backwash rate. Too high and it will blow all the Cation out of the tank. Look inside the fittings that contact the backwash water. If there is a large amount of brown plaque or any plaque, you probably shouldn't run raw water through the HX. At some point, one hotter fluid comes in contact through a HX and TDS will separate out of the raw water. forming an insulating plaque. Just like what happens to indirect coils in indirect water heaters. Boiler tank-less coils.