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    makeup water problem (7 Posts)

  • DSB DSB @ 2:40 PM
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    makeup water problem

    We have a geothermal heat pump system at a new high school. The system has 264 400' deep wells. Starting at the beginning of this month we have noticed (through the makeup water meter) over 400 gallons of water have entered the system. There are no leaks in the building. No leaks have been found on site. And the water flow is not constant. The water flow actually happens when the well field loop pump is running. The static pressure of the system is at 28 psi when the loop pump is off. As soon as the pump comes on the system pressure drops to 15 psi and slowly rises back up to 25 psi. Meanwhile makeup water is entering the system.

    The only odd thing with the way the system is piped is that the loop pump is pulling water from the well field (not pushing into the field) and it pumps water towards the suction side of the building pumps. So when the building pumps and the loop pumps are running the building runs at a much higher pressure compared to when only the building pumps run.

    Any ideas on why we are seeing this makeup water enter the system. And if we have no leaks where is it going?

    The system has been running for 6-9 months before this started happening.

    One thought I had was this sympton somewhate corresponds to when summer school started and the temperature outside increased. Could we be seeing the well piping expand due to increased loop temperatures?
  • Jamie Hall Jamie Hall @ 2:46 PM
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    It's got to be going somewhere...

    you just haven't found it yet.  I presume this water can get into the well field?  If so, 400 gallons over a month is not going to be visible.  With that many wells, it may also be a real headache to find!

    As to expansion.. no, sorry.  No way is the volume of the system going to expand enough to soak up that much water.
    Jamie

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • DSB DSB @ 2:59 PM
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    makeup water problem

    The make up water meter only shows flow when the pump is running. There will be no flow all night long and then flow from the meter tracks exactly with status of the pump. Seems like if we had a leak it would be constant. Just playing devils advocate...
  • Jamie Hall Jamie Hall @ 4:46 PM
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    Pump seals

    ???  Back when I had to contend with pumps, I had something like that a couple of times; turned out it was seal leakage on the pump.  Not saying it is, mind you, but that I did have that a couple of times.  10 gallons or so per day sounds like a lot, but it really isn't that much and might even be evaporating rather than leaving a damp spot, particularly if it is a mist or fine spray.  You might see some deposits from that?
    Jamie

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • DSB DSB @ 4:56 PM
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    makeup water problem

    Thanks for the suggestion but there are only 3 pumps and we know they aren't leaking.
  • Zman Zman @ 5:22 PM
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    Expansion Tank

    Is the fill on the suction side of the circs? Where is the expansion tank located? Do you have a relief valve?
    I was thinking that if the circ is pumping towards the tank. It would lower pressure on the suction side causing the fill valve to open. When the circ turns off the pressure would stabilize at a higher pressure triggering the relief valve.
    Just a thought,
    Carl
  • Solid_Fuel_Man Solid_Fuel_Man @ 7:28 PM
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    Zman....

    My thoughts exactly.
    Always keep learning: observing what works, and what doesn't. Ask questions
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