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U.S Power DX Geothermal System Problems

frederickm Member Posts: 3
I have a U.S. Power DX Geothermal system , installed in 1992, and having problems with the compressor and accumulator tank icing. I wrapped both with heat tape and stopped the icing. This year I forgot to turn on the heat tape and began to hear some slugging on startup and after turning on the heat tape was still hearing it once every few days.
I have a Copeland Scroll type compressor and have heard that it will handle some slugging without damage??
Is the system over or undercharged? I have added a small space heater to warm the compressor and accumulator tank.

The copper coils are in 12 ft. deep x 24' long trenches in a spoke shape pattern of 5 total with copper tubing fastened to oak stakes (6 Ft. high), 2 in each trench, one fastened on each side of the 2' wide trench.


  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    Why don't you start by telling us anything that was ever done to the system.
    Did it ever work properly and if so, under what conditions?
    How many Tons is the system?
    What is the heating load of the house?

    While a scroll normally won't mechanically break from a slug coming through, it is still very undesirable. If it is a slug of Freon, it will dilute the oil in the compressor and cause mechanical wear and ultimately a compressor failure. If you are slugging with oil, it means oil is accumulating in the loop field due to low Freon velocities. If the oil is in the loop field, it isn't in the compressor. Do the math.

    Based on the earth coverage of your loop field, I would guesstimate you have about 1 ton to "if you are lucky" 1-1/2 ton of heat exchange capacity to the earth. That is a SWAG (scientific wild *ss guess) There are a 1,001 variables in a ground exchange loop field.

  • frederickm
    frederickm Member Posts: 3
    The unit is 4 ton and has had a larger accumulator tank added and a new updated valving apparatus was added which I do not know the details of.

    I did some research and found that this system needs more freon in the cooling mode and less in the heating. An experienced HVAC contractor from Ohio with these DX systems told me that he has a number of clients on a maintenance schedule and removes some freon in the fall( until the discharge line is about 150 degrees) and puts it back in in June. Does any of that make any sense??

    One website stated that sometimes 3x more freon is required in the cooling mode.

    Is the oil laying in the field because of low temperature?
  • frederickm
    frederickm Member Posts: 3
    US Power DX System Problem