Iowa Troubleshooting Hot Ground Loops

Discussion in 'Maintenance and Troubleshooting' started by Links56, Sep 25, 2016.

  1. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    You could not be more wrong with every one of your statements.
    The people loads and the kitchen loads are always the problem for cooling in restaurants. Exhaust makeup air or infiltrating air are the other problem. Last but not least is the hot water consumption.
  2. mrrxtech

    mrrxtech Member

    Where does 121 degree EWT come from on the 5 Ton Unit? Why does the 6 Ton EWT read 110 degrees while the 5 Ton EWT is 121 which happens to be very close to the LWT from the 6 Ton Unit. If you are right about 2 separate loops, the water EWT for both Units would be 110 degrees.
    The only way EWT could reach 120 degrees is from the 6 Ton Unit feeding into it.
    Check again, the loops are in series.
  3. ChrisJ

    ChrisJ Active Member Forum Leader

    Sounds like the radiant side of the Cypress unit is still heating the buffer tank, probably switches modes when the a/c is turned off overnight.

    So then it takes a little heat out of that loop.
  4. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    You could not be more wrong with everyone of your statements.......

    121F comes from unit cooling load and runtime being to high for the loop field. 110 F means ratio of load/runtime to loop field capacity is high.
    2 heat pumps serving 2 different zones with 2 different loops. One having a higher cooling load and ejects more heat into the ground in relation to the loop heat rejection capacity, resulting in high temperatures. Why is this so hard to understand?
    Trust me, if your load is too high and you loop to small, you will have 120F as a loop temperature.
    Last edited: Sep 30, 2016
  5. mrrxtech

    mrrxtech Member

    OK, the old intermediate tank cooling trick.
    I always overlook the possibility of tanks being involved since I tend to think in Water to Air Geothermal Systems.
  6. Links56

    Links56 New Member

    As the run time gets less because the temp outside is less, the loop for the dining area is running considerably cooler. The kitchen is still 120-130 because all the heat coming off those walk-in cooler compressors mainly and other equipment. The magnolia unit also has a DHW/AUX pump on it so I am planning on getting another indirect tank and in the summer using the 2 indirect tanks to make potable hot water for the building. Also add another 5 ton of conventional cooling that is controlled by the EWT.

    In the winter I think the indirect tank is robbing all the heat from the loop trying to heat the heated floor thus causing the cypress unit for the dining area to kick on the aux heating element all the time. There is no other heating method for the heated floor just the water from the cypress unit aux pump. There is a heating element in the indirect tank but it is not hooked up, I will wire this up so it can heat the floor in the winter

    I'm thinking on waiting to relocate the walk-in cooler compressors so I don't lose the heat they are giving off this winter.

    Hopefully with these changes the building will be better than it was. Time will tell. Thanks for all the advice and help, I appreciate it.
  7. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    It may be worth noting that actual cooling capacity falls way below rated / nominal with triple digit EWTs
    In this case the two systems totaling 11 tons may actually be delivering about 8 tons. Adding insult to injury, EERs are likely running in the single digits.

    If the restaurant has very high potable hot water demand there may be an opportunity to preheat potable water using an indirect tank (s) working off the LWT streams - possibly fewer moving parts and lower cost than a dedicated WW heat pump.

    Thinking a bit further out of the box:

    1) ThermaStor makes commercial sized heat recovery water heating tanks - applying one or two might result in a bit of a "Frankensystem", though.

    2) Ensure that the commercial kitchen hood's discharge air flow has matching make-up air - Restaurants often experience unbalanced hood flows / insufficient makeup air. The flow difference is made up by air drawn from the kitchen, in turn causing conditioned air to be drawn into the kitchen from the dining room, in turn causing the dining room to draw air from outdoors. That greatly increases cooling load on hot days. A mismatch of only a few hundred CFM will add tons to the cooling load.

    3) Could the cooler compressors use outdoor condensers in summer and indoor condensers in winter? Alternatively, could the cooler condensers be configured to use loop water instead of indoor air? (This would shift their impact from kitchen ambient air to loop water, possibly robbing Peter to pay Paul)

    The cooling compressors, since they are year round in cooling mode, might be the best source for heat recovery into potable water.

    4) The triple digit loop temps might lend themselves to transferring heat to outdoor air via a radiator or "dry cooling tower" particularly at night.

    5) The fact that the system struggles summer and winter suggests way undersized loops. Is there a way to add capacity via vertical bores?
  8. mrrxtech

    mrrxtech Member

    My Trane Unit has a fuse for the Desuperheater Pump that they recommend pulling during the heating season. This puts all of the Geothermal Units heat into the house rather than trying to store it in the 80 gallon hot water tank.

    The electric company can heat my hot water, since my Trane Unit struggles to keep the house warm in the Winter due to cold loop temps. If I can find a trencher on a trailer to rent, I'll add more ground loop and solve my cold loop problem.

    If you can turn off the desuperheater pump in the winter without damage to your desuperheater the Aux Heat might not run as much.
  9. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Any system whose owner is advised to seasonally remove / replace a fuse is clearly not ready for prime time.

    While I understand the impulse to disable desuperheater recovery in order to maximize heating capacity and reduce auxiliary resistance heat run time, the reasoning is dead wrong in the case of electric resistance water heating finishing tank.

    Every Btu transferred for water heating reduces electric resistance water heating, so even if there is a 1:1 relationship between heat pump system capacity diverted to domestic water heating and aux heat usage, so what? Both are resistance loads, so no net change in consumption.

    The actual reality is that most reasonably sized systems properly maintained experience very few hours each heating season during which they can't meet heating load. 95% or more of the time they have capacity to spare. Letting them run a minute or two longer during each part load run cycle lets them build hot water at a COP of 3 or better, compared with electric resistance COP of less than 1.0

    Disabling desuperheater / hot water heat recovery during heating season is penny-wise but pound-foolish.

    MisterWrecksTech once again demonstrates that he is unmoved by facts and unencumbered by rigorous thought processes. Readers here should take his advice with a very large grain of salt.
  10. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Curt hits the point here. Why would you force a heat pump through more short cycling most of the part load time, only to heat your water with electric resistance heat. Who give that kind of advise does not seem to understand the technology well.
  11. Links56

    Links56 New Member

    What would I have to do to add a second compressor outdoors for the walk-in coolers? Can I just tee into the lines for the existing indoor compressor with a line set and run it outside? Will i need to isolate the 2 systems? What do you recommend? Its 25 feet from the indoor compressor to where I would like to put the outdoor compressor. Thanks.
  12. mrrxtech

    mrrxtech Member

    Working with the Freon System is one of the few things I can't do due to government regulations to start with. If I bought a Freon Collection Device and took the exam & passed which I have no doubt I could do since I've seen the study guide, then there's the knowledge of how to size and add a compressor onto an existing cooler, and the brazing skill I lack since I've only dealt with copper house plumbing soldering.

    No doubt I could find a reference and come up with an answer, but this would be an easy job for those who work on the Freon side in the industrial cooling business.

    Maybe someone on this site has that background and can give you some advice.
  13. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Despite the fact that Mr Wrecks Tech makes it sound so easy for anyone with a study guide and "Freon Collection Device" (more properly - Recovery Machine), it actually is no small matter to add a compressor to an existing refrigerant circuit or system, regardless of one's brazing skills.

    There are all manner of considerations:

    1) Charge management
    2) compressor operation sequencing / controls
    3) Compressor oil return
    4) refrigerant piping sizing / routing valving etc.
  14. Links56

    Links56 New Member

    Is there any other options so I can utilize the heat output in the winter but not in the summer?
  15. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Two separate systems.

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