British Columbia Geothermal Heat pump not keeping up

Discussion in 'Maintenance and Troubleshooting' started by Doug Medley, Mar 15, 2019.

  1. Doug Medley

    Doug Medley New Member

    This is my first time on here. Just a matter of note my back ground was E&I Tech., so have a technical background. I have lived in a complex for 7 yrs, bought house new, with 60 houses on a geothermal system. The system is open loop & I am assuming supply & return form 2 loops supply loop & return loop, with take offs for each house & return water going into main return loop. Most houses are upwards of 12 years old. To my knowledge there have been no problems with heating until this year. We have experienced lower than normal temps. Sometimes below 0 deg C for longer periods of time. There have been problems with upwards of 15+ units. I am not sure of exact number. I have asked around & some units are keeping up fine while others do not. Some units have had problems within units themselves & others have not. In my case the HVAC Tech made a modification to my unit to take care of potential freezing conditions within unit. I hope I understood this correctly. My unit works better somewhat. Still not totally satisfied. My unit was supplying air with a temp. of 30 Deg C & then one day dropped to 20 Deg C. I had determined that the 30 Deg C is a normal temp, from over the years of checking. One resident replaced his unit with a Bosch & still has problems. I believe most units, at least mine is a Climate Master 2T unit. I did a rough calculation & came up with a size of 2.5T. I do know some others are identical. I do believe water temp, dont know what temp is, is lower than previous years as I always noticed that over water lines snow would not accumulate until larger amounts of snow had fallen. Then when you shoveled over these areas snow was always slushy. I am not sure how deep these lines are buried. Not confident they are lower than 3-4 ft. Also I am assuming water pressure will play a big part in efficiency as well. With more units calling for heat is it possible that pressure will drop below a level where system works efficiently?? I hope I have supplied enough information to have someone provide some hints as to what problems we may be experiencing. As a matter of note I live on west coast of Canada where temps are normally above freezing, & may drop for a day or 2. This year we have experienced upwards of 2 weeks below freezing.
     
  2. IsItForMe

    IsItForMe New Member

    Hi,

    Are all of your neighboring houses sharing a single open-loop well? Or does each home have its own?

    I’m no pro - just asking for clarity.
     
  3. Doug Medley

    Doug Medley New Member

    We all share same well
     
  4. arkie6

    arkie6 Active Member Forum Leader

    Where does the return water go?
     
  5. Doug Medley

    Doug Medley New Member

    Return goes back to source
     
  6. arkie6

    arkie6 Active Member Forum Leader

    Returns back to the source via the same well or a different well?

    What is the entering and exiting water temperature to your unit?
     
  7. Doug Medley

    Doug Medley New Member

    I have no idea what temps are. I could get a water sample of the exit but not entry.
     
  8. arkie6

    arkie6 Active Member Forum Leader

    You don't need a water sample. Does your unit have Pressure-Temperature (PT) test ports at the water inlet and exit? These are typically installed in the elbow of the water inlet and exit pipes right on the front of the unit. If so, you can remove the small cap and insert a thin (<1/8" dia) meat/cooking thermometer into the rubber insert inside the port and take a temperature measurement. See example below of a typical PT test port (also known as Pete's ports):

    [​IMG]
     
  9. arkie6

    arkie6 Active Member Forum Leader

    If you can get a water sample at the exit and measure the temperature as the water is flowing out of the loop pipe that would suffice. If your open loop system returns the water back to the same well (this is called a standing column well), the water temperature could be dropping to near freezing. Then when the water flows through the geothermal unit coaxial coil, the water temperature drops even more as the geothermal unit pulls heat from the already cold water. If you measure water temperature exiting the unit is only a few degrees F or C above freezing, there are points within the coil that would be at the point the water could be freezing to the cold internal refrigerant lines which partially blocks flow and insulates the cold refrigerant lines from the relatively warmer loop water. Most geothermal units have a temperature switch setting that shuts the unit down if open loop water temperature gets below ~38 deg F (~4 deg C). This low temperature cut-out can be bypassed if you have a closed loop with anti-freeze in the loop, but there is obviously no way to add anti-freeze to an open loop system.

    You said "In my case the HVAC Tech made a modification to my unit to take care of potential freezing conditions within unit." What exactly was done? I wonder if he bypassed the low temperature cut-out to keep your unit from locking out on low temperature, but now it is actually freezing inside the unit and blocking flow.
     
  10. mtrentw

    mtrentw Active Member Industry Professional Forum Leader

    If you can share a picture of your unit with entry and exit pipes, some could help with suggestuions.
    I think critical info would be an understanding of incoming and leaving water temperature. If you can't find ports to push a thermometer in, then you may be able to remove some insulation and get a temperature of the pipe surface which isn't as precise, but gets good ballpark info and change temperature from entery to exit.
     
  11. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    This is an open system. So the entering water temp is given.

    The leaving water temp is limited to about 38-39F min.

    There is not much which on the water side which will affect the capacity of the unit. Even if you have a few gum lesser flow, that will not affect very much the capacity of the unit.

    So as long as the unit is running, it gets enough flow to operate, and the If there is a lack of capacity, on this kind of open systems, in MO......it likely comes down to the refrigerant circuit. Unless the controls do not work proper.
     

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