Hard Water Compatibility Open Loop Heat Pump

Discussion in 'Solar and Geothermal Water Heating Forum' started by type@uwm.edu, May 12, 2008.

  1. type@uwm.edu

    type@uwm.edu New Member

    Messages:
    13
    Hi-
    I'm contemplating using water from a residential 6" well I'll be drilling soon for an open loop system. Most of the wells around me are 100-150 ft deep and have high iron and mineral content. I assume that the minerals build-up in the coils and/or elsewhere. Is there a work-around for this in an open loop system (pond discharge)? Does some equipment lend itself better to cleaning? I assume it would be too expensive to treat the flow. Thanks! Rob D.
  2. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    Question 1. what's your water table level?
    If the static water table level is too low you will spend a bit of energy pumping the water.

    Question 2. can you pound a separate shallow well.
    It's generally better to use "shallow" water for heat pumps since they generally have less minerals.


    The key to "open" or "pump-n-dump" systems is fittings, valves, cleaners and materials.

    1. don't use any cast iron parts.
    only use plastic, copper, brass, bronze parts.

    2. Add disconnect fittings or use Barb end pex fittings.
    This will come in handy when you are using a drill pump and cleaner to flush out the unit. This cleaning should be part of your once a year maintenance.

    3. Keep an eye on your total water usage since some states have limits.
  3. Gary Slusser

    Gary Slusser That's all folks!

    If you have hard water, scale will build up in the heat exchanger reducing the efficiency of the system, and if there is high iron in the water, rust can block things up too. Water treatment equipment would have to be used and sized for the peak demand flow rate of the system. That could get very expensive.

    Thereby, a closed loop in ground system would be much better and much less expense.
    Last edited: May 12, 2008
  4. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    The really great thing about ground source heat/cool systems is how they can be built up "a little at a time" and changed as needed.

    Right now I am just using blue barrels outside and a recirculating pump.
    I have copper pipes in each blue barrel so the pump is recirculating distilled water.

    The water temperature averages out and I can use the water to directly cool the equipment thus saving the need to use a heat pump.

    Latter on this summer I plan on pumping well water into the barrels to cool them when needed.

    I also have a 2 ton "Condenser" that I got off freecylce.com . I ripped the bad compressor out of it and plan on pumping water threw the coils on cold days to cool the water.
  5. type@uwm.edu

    type@uwm.edu New Member

    Messages:
    13
    That's encouraging. Do you think some coils/heat pumps could be easier to clean than others? I'm having a hard time researching equipment options on-line. Could anyone point me to a ~3 ton heat pump that's suited for an open system so I can get a better idea of what is involved? Rob D.
  6. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    Why use the heat pump then?

    Whats the water temperature?

    I've never heard of any laws saying you can't have extra wells.

    There are laws saying all wells have to be able to be pulled from the outside.
    There are laws limiting how much water you use.
    There are laws covering "abandoned" or "unused" wells.

    There are several reasons to use a separate well
    1. You are not pulling lots of water from the deep aquifer. Study's have shown that there is a higher chance of increasing the contaminants in a aquifer as you increase the amount of water removed.

    2. Lower pumping costs since you don't have to pressurize it to the house water pressure.

    I've not seen any units designed for open loop systems.

    One thing you could look for is the maximum water pressure that the unit can handle. The higher the pressure, the thicker the walls.

    The thicker the copper, the longer it will last since even more gentle cleaners will over time erode the coper.

    The cleaning process involves disconnecting the unit water lines and using a recirculating pump (like a drill pump) to pump a cleaning solution from a bucket around and back into the bucket. (FYI: I like to use a white vinegar solution)

    Some people don't do anything until the units "plug up" after ~10 years.

    For those that say that efficiency is reduced... Find a more efficient unit and run it at lower speeds.

    PS: This might be better in the HVac section.
  7. type@uwm.edu

    type@uwm.edu New Member

    Messages:
    13
    Sorry about that. I post follow-ups there. Rob D.
  8. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    Actually, the mods have a way to move topics and moving topics is better than having more than one thread for the same topic.

    The well question is on-topic in this section. I'm just thinking that the heat/cool and heat pump questions would be better in the HVac area.
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