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Thread: Hard Water Compatibility Open Loop Heat Pump

  1. #1

    Default Hard Water Compatibility Open Loop Heat Pump

    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. #2
    Computer Programmer Bill Arden's Avatar
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    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.
    Important note Ė I donít know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

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    That's all folks! Gary Slusser's Avatar
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    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.
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    Computer Programmer Bill Arden's Avatar
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    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.
    Important note Ė I donít know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

  5. #5

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    Quote Originally Posted by Bill Arden View Post
    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.

    Hi Bill-- Answer: I'm not sure about the static level, I suspect it could be pretty high. I'd use the heat pump only for air-conditioning.; we'll have a masonry heater for heat. I own a Grundfos SQFX-11 submersible pump that could give me 6-10 gpm on my existing Solar panels. My thought is to try the Grundfos (with 110 AC augmentation as needed) first and a large pressure tank first to see where I stand..

    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.

    Answer: Interesting,.. I have an old 50' well with 4" casing and plenty of flow. I was told that state probably won't let me keep it. It has lots of iron; Silly me, I thought deeper wells had fewer minerals. I could probably get plenty of water at 30-50' from another new well, but its not that expensive to insure the additional capacity from my new well. I'll try the simplest solutions first. I was concerned about investing in equipment that would be destroyed.

    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.
    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. #6
    Computer Programmer Bill Arden's Avatar
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    Quote Originally Posted by type@uwm.edu View Post
    I'd use the heat pump only for air-conditioning.
    Why use the heat pump then?

    Whats the water temperature?

    Quote Originally Posted by type@uwm.edu View Post
    I was told that (the) state probably won't let me keep it.
    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.

    Quote Originally Posted by type@uwm.edu View Post
    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.
    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.
    Important note Ė I donít know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

  7. #7

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    Quote Originally Posted by Bill Arden View Post
    Why use the heat pump then?

    Whats the water temperature?

    50 degrees. I see your point. I'm going to meet a contractor who is finishing a closed-loop system tomorrow. He said folks are even using car radiators. Just need ways to rid the condensation and reduce the humidity of the output. Room dehumidifiers perhaps, something before the ductwork would be better.


    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.

    The well driller suggested it was not up to state "code." Maybe I can plea that its perfect for this use.

    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 copper.

    Good tips

    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.
    Sorry about that. I post follow-ups there. Rob D.

  8. #8
    Computer Programmer Bill Arden's Avatar
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    Quote Originally Posted by type@uwm.edu View Post
    Sorry about that. I post follow-ups there. Rob D.
    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.
    Important note Ė I donít know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

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