Wanted Feedback (and a little engineering)

Discussion in 'Geothermal Heat Pump Applications' started by HVAC Technician, Apr 28, 2014.

  1. I have read some posts on "thermal batteries" or water heat storage. A year or two back I attended a "Preppers conference" which was very informative. Basically it is preparing in all sorts of ways for a hurricane Katrina or "natural or unnatural catastrophe".

    We talked about the necessity of water and what happens when electricity disappears. So there were seminars on digging wells and how to get water out of the ground and so on.

    My wife is also interested in either having a second well or at least reliable water during emergencies. And there are some things you can do. There are booster pumps, for example, that can boost water pressure to 50 psig. They can be powered off 12 or 24 volts DC using batteries and solar panels.

    So then I thought: I am already returning a constant water flow to the aquifer from my heat pump "wasting" the water. Why not store between 500 - 1,000 gallons of water above ground AND repump or recycle that water back to the house over and over ? For heat pump ?, cooking, toilets, washing laundry and showering ?

    What I need: 1) Emergency water that can be pumped from solar or batteries 2) the ability to boost daylight water temperatures of stored water 10 - 20 degrees during winter months (to increase efficiency) 3) the how to of building a copper tube thermo syphon solar water heating system.

    Thoughts, you creative people ?
  2. ChrisJ

    ChrisJ Active Member Forum Leader

    "3) the how to of building a copper tube thermo syphon solar water heating system."

    To see all sorts of DIY solar stuff check out builditsolar.com

    I think heat pumps would freeze up 500- 1000 gals pretty fast in winter.

    Could your returning "waste" water flow to a large tank before it goes back to the aquifer? So when you have no electricity you would still have a large amount of water, then use a 12v pump run off a solar panel/battery to bring in water.

  3. OK, this is just a discussion. Whether I use say a 500 gallon tank or say two 500 gallon tanks for 1,0000 gallons, yes, returning 49 degree water in a 28 degree ambient would freeze. But one, that water could be heated during daylight hours, raising the temp from 49 degrees to 75 - 80 degrees (peak sunny daylight hours) AND with a heat pump in constant operation AND an overflow pipe (which would feed back into the original drainage system) 49 degree water would be MOVING through those tanks at night in the middle of winter. Remember we are trying to "hang on" to 500 or 1,000 gallons of water, but we want to add heat if that is practical, at least in the winter. Does that help ?
  4. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    I would do water storage with chlorine injection for return usage to domestic service. The tank would be bled off by temprature or fill level or both to suit your needs. The concept of battery geo storage has been tried and failed, It needs to re-supply at some point to off set heavy loading.
  5. ChrisJ

    ChrisJ Active Member Forum Leader

    "Why not store between 500 - 1,000 gallons of water above ground AND repump or recycle that water back to the house over and over ? For heat pump ?"

    I'm sorry I thought you wanted to run the stored water through your heat pump over and over like a closed loop, that I thought would freeze.

  6. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Bury a poly septic tank in the yard.

    There was a guy here who went by "designer Mike" who built a solar thermal/geo hybrid system. I know because I shipped him his heat pump.

  7. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    James Schenck at Thermal Battery systems is doing just this sort of thing. Noting the advantage of a greater delta T heating geo loop water than domestic hot water offers much greater transfer of BTU's. Has has been monitoring some installed equipment and has developed some nifty controls. He runs the group "multisource heat pumps" on Linkedin.
  8. James Schenck

    James Schenck New Member

    Thanks for the referral Joe. Regarding the solar aspect, I agree with Chris J about builditsolar.com, a great resource with tons of information. I also agree with Mark; bury a poly cistern tank. (Or a concrete one)

    The concept of a "thermal battery" geo system means different things to different people. Like anything else, the merits or lack thereof will be defined by the details. For example, connecting a heat pump to the actual water running in and out of a tank is entirely different than running the heat pump on a glycol closed loop HX that is inside a tank full of water. So there are many ways that systems can be integrated and some work better than others. We are working on developing some standardized methods for hybrid system integration but things are still very much "in development". You will get an idea of what we have been up to by looking around our Thermal Battery System website and youtube channel.
    Tamar likes this.
  9. ChrisJ

    ChrisJ Active Member Forum Leader

    James I see you guys have a welserver site but it has not been live for a while. Will it be operating again soon?

  10. James Schenck

    James Schenck New Member

    Hi Chris, We were using welservers before but we switched to controls that do the control and data logging with the same equipment. We had them on three systems. I think one of them we have in South Dakota is still online but I have not looked in a while. It would be tough for anyone not familiar with the system to make any sense of the data. We are getting better at processing the data but we are still learning as we go.
    ChrisJ likes this.
  11. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Looking forward to the Cliff's notes James :D
  12. ==========
    I'm not a water well guy, or a very good plumber. A concrete tank I sort of understand, (like septic tank ?) although I have no idea if they hold water like a steel tank or whether water leaches through concrete. I'm dumb, huh ?

    I know from some of the Prepper information, that there are water storage tanks made out of artificial materials which are often used by farmers, etc. above ground. They can tolerate 90 degree temperatures and being in the sun all year. The idea of storage underground is interesting. (not much BTU gain/loss) Beside burying it where your water lines and 220 volt power cable for your well ARE NOT, I imagine we would have to go at least 10 ft. below ground level. To take advantage of solar heating, I suppose you could power an 003 Taco pump by solar panels to circulate heated water from the solar panel to the body of water. I can see some possibilities of running THAT in parallel with the original well system.

    If the 50 psig booster pump ran off batteries and solar, probably could reduce cost of moving water, lower power use ...

    What is a poly cistern tank ?
  13. James Schenck

    James Schenck New Member

    HVAC Tech, A poly cistern is the made out of same stuff that you are thinking of when you refer to the water storage tanks used by farmers. The difference it that it is corrugated for strength so that it can be buried. Vertical wall tanks would collapse if buried. Yes concrete tanks can and often are used as septic tanks and they also use the poly tanks in septic systems. Just google underground cistern tanks and you'll find plenty of examples.

    You won't be able to bury a poly one 10' deep. The manufacture has a posted maximum burial depth measure from the the of the tank to the surface. It ranges from about 2.5' to 3'. This puts the bottom at 7'- 8' down depending on the tank. There are also instructions on if the tank must be a certain amount full before backfilling or if it can be empty.

    If you insulate the entire burial cavity you will retain the heat better but depending on the application you may not want to do that. When used in conjunction with heat pumps we can use any thermal energy all the way down into the freezing point of water. In northern climates the buried tank will spend more time below earth ambient temperature than above it. (depending on the size/capacity of the solar or other inputs) This means it could and would be absorbing heat out of the surrounding earth just like geo loops do. If it is insulated it can't do that so ALL the energy inputs would have to come from somewhere else like from the solar collectors or external loops or an open source flow through the system.

    As a guy who claims to not be much of a water guy, the main thing I would stress is to think through any health risks that may be present with what you will be doing with the domestic water. As a rule, I don't like to have any crossover of systems that are designed to condition spaces and systems that deliver domestic water. Storing large amounts of water can be tricky enough but if it is also being thermally altered by heat pumps and solar and it is being pumped around a mechanical system it adds a whole new level of potential liability.

    The plumbers I used to work with would freak out every time they would find the domestic water heater hooked up to a radiant floor system. (And still plumbed to the domestic system) Google legionnaires disease. You don't want tepid stagnant water that has been sitting somewhere for months making its way back into your water heater and then getting atomized in your hot shower. (I am not saying you were going to have anything like that occur with your plans I just want to emphasize that these things should be known and addressed with whatever you do.)
  14. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader


    Hello and welcome.

    <<< goes to help the daughter and meet the new grandson and son-in-law in the wilds of Southeastern Ohio, where they use billboards instead of phones, and a FNG shows up knowing what a poly septic tank looks like and why.

    Not only that he is working on hydronic storage.

  15. James Schenck

    James Schenck New Member

    Hi Mark,

    If you have any more info I would be interested to hear how your contact 'designer Mike' has his system set up and how it is working. I think that it would be beneficial for the geo industry to have access to as much of this info as possible. It is amazing how often I hear "it won't work" when we have not even been able to define what "it" is. My view is that there are lots of reasons that thermal storage and heat pumps and solar etc should be combined but the details of what "it" is will define the merits of the design. I'll be the first to say that there is virtually no situation I can point to where I would do things exactly the same if I could do it all over again. Sometimes I learn in bigger ways and sometimes in smaller ways but more perspective is nearly always beneficial.
  16. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader


    Good old Phil, our system admin, here. I found an old PM with Mike's contacts at the time. I will send off an email and try to phone him later today. I will let him know you are looking to learn what he did.

    I am on the road working a very slow IP through my wife's smart phone, so I have not tried looking at your product on line.

    I got started doing this stuff after reading, in Mother Earth News, founded here in Ohio, about a guy in France that built a compost pile on top of some HDPE pipe and used the warmth generated from the compost to heat his home. My wife says I am an old hippy, but my drug of choice is the one that helps my joint pain.

  17. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader


    Game on with Mike and his system. He is a free thinker with an EE degree. I like how he thought and did what I could to help him build his system. I have yet to see it work, but I will.

    I like what you are doing and did run through your product. Good work, I can shorten the learning curve if you wish. I came hard wired for heat transfer and electrical controls. Try me.

  18. James Schenck

    James Schenck New Member

    Mark, Thanks for the comments and support. I look forward to hearing about the system Mike has installed. I am a bit out of the loop this week as I am in South Dakota at our Energy Dynamics training / dealer meeting. Our efforts are currently on the "backend" of controls and data logging. We continue to look for and collaborate with other innovators who are moving the whole "multi-source" concept forward but our main thrust is on software development at this juncture. I hope that in a couple months we will have some software that will be beneficial to all of us interested in heat transfer and controls.

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