New York Geo shuts down at 24.5 lwt

Discussion in 'Maintenance and Troubleshooting' started by donnie p, Apr 30, 2019.

  1. donnie p

    donnie p New Member

    Last 2 years when the temps dropped into sub zero, the geo shut down...LWT looked to be about 24.5 at the time. I know there should have been more from a make up heat source but I was in the south and my backup plan failed.
    At any rate, what should the antifreeze solution be good to? I did a freezer test and at 24 degrees the "water" is thickening...20 no slush but heavy...18 light slush...14 heavy slush. The system uses glycol.
    Any thoughts on this?
     
  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    What brand geo unit?

    Is the dip switch set to antifreeze, meaning does the heat now that there is antifreeze in the loop? 24.5 LWT might be at the edge of 30F EWT, right where the wrong dip switch setting would make a heat pump trip.
    Despite the freezer test, you might have not enough antifreeze in there. Keep in mind that the tail end of the heat exchanger might be much colder. so you might have ice formed on the inside of the coax, reducing the temps in the refrigerant, which will trigger an COAX freeze detection error.

    What was the error code which triggered the shutdown.
     
    Last edited: Apr 30, 2019
  3. donnie p

    donnie p New Member

    Thanks Doc...I have a McQuay. The EWT at shutdown was around 30F I suspect. It was a self install unit about 7 years ago. There was a slow leak in the coil that was not detected until after year 5. Recharged a couple of times. Had that replaced (a month or 2 after warranty of course). This unit has been a godsend for a big old farm house. Decreased utilities immensely.
    Not sure what the dip switch setting is. I would definitely swap out the "water" to a better solution if that would help.
     
  4. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Many reasons. Sometimes they leak water when exchanging the coil, and replenish only with water, bit not antifreeze, diluting the antifreeze. Or the refrigerant is low on change, causing colder refrigerant temps. Of have a wrong dip switch setting, telling the unit that you don't have antifreeze in teh coils, shutting of on freeze protection at 30F entering water temp.

    Would be good to know the error code, which tells you why the unit shut down.
     
  5. donnie p

    donnie p New Member

    Thanks Doc...I do not know how to check for error codes or the dip switch. I am located in Castile NY...is that anywhere near you? Would you be willing to come here to do a consultation/repair? Would sure appreciate it.
     
  6. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    It is a bit outside our area.

    What is the model # of your unit?
     
  7. donnie p

    donnie p New Member

    Thanks Doc. Here are pics of the company specs tag (Model# at the top) and a schematic with the lights (code indicator?) at the left. I can send you a pics of the electronic board if that will help. I am not sure where to check for the dip switch setting.
     

    Attached Files:

  8. wing

    wing Member

    Have you considered changing out the loop fluid to an ethanol anti freeze mix ?
     
  9. donnie p

    donnie p New Member

    I would certainly consider that. The dip switch setting is something I am not familiar with. It does seem the unit shuts down when the EWT is about 30 degrees so like Doc said that might be the culprit.
     
  10. ChrisJ

    ChrisJ Active Member Forum Leader

    Don't know if you have this manual.

    I read through it but didn't see any dip switches. It says in a couple places that the operating range is 30*F- 110*F

    Equipment Protection Control – The MicroTech III
    unit controller receives separate input signals from the
    refrigerant high-pressure switch and the low suction line
    temperature sensor. In a high-pressure situation, compressor
    operation is suspended. In a low temperature situation,
    the unit goes into a defrost cycle where the unit is put into
    cooling operation for 60 seconds until the coaxial heat
    exchanger is free of ice. Each switch generates its own
    unique LED status and output is available to a “fault” LED
    at the thermostat if either situation exists. For additional
    protection, unit sizes 019 and larger have a 7psi (48 kPa)
    low pressure switch to protect the compressor from low
    refrigerant charge. The low setting prevents nuisance trips
    while providing additional protection.
     

    Attached Files:

  11. donnie p

    donnie p New Member

    Thank you so much Chris. So it seems like it might be factory set to shutdown when the EWT drops below 30 degrees. If that is the case I will just have to add more supplemental heat before that happens.
    This year was a bit of an anomaly. I lost control of the Honeywell RTH9585 thermostat (was in SC). Honeywell decided to do an update (the firmware?) during a time when the entire northeast was in sub zero temps. They sent an email before hand saying the thermostat could lose functions during this time (for a week or 2 span in January) and mine did intermittently. I had planned to drop the geo temp down a couple of degrees and 2 gas space heaters were set to kick on to help. Oh well...best laid plans.
     

Share This Page