reversed loop?

Discussion in 'Maintenance and Troubleshooting' started by ant, Feb 3, 2012.

  1. ant

    ant New Member

    Our geothermal system was installed a few years ago. During the summer it works great for A/C but in the winter as the temperature drops to freezing, our heating can't keep up.

    We have a Climatemaster Tranquility 27 two stage 5 ton geothermal package with two 400ft wells and a desuperheater tank.

    I looked at the temperatures in the ground loop at the first bend after the loop pumps using a couple of electronic thermometers logging to a laptop. The return water temp EWT is about 56F when the system is running. However the water entering the pipe is always 1F or so warmer (I checked I had my probes the right way around a number of times and even reversed the probes). Also the pipe to the pre-heat tank is always very, very hot when the heating is running even though the system doesnt seem to produce much air heat. Eventually the house thermostats panic and try and bring on the AUX heat.

    What should the typical temperature difference be for a ground loop in Maryland? Why is the LWT warmer than the EWT? Could the ground loop be reversed and the unit still heat and cool to a limited extent? Is this a indication of something else wrong? How can I tell?
     
  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    If you reversed the probes, and you are confident that the temps are valid, then there is something wrong with your refrigerant circuit. Delta t on the source side should be between 3-5 degrees in first and 4-7 degrees in second stage, depending on your flow rate.
     
  3. ant

    ant New Member

    Thanks for the reply. It's good to know what those delta t numbers should be. I'll check the callibration of my probes soon (Im away today).

    However I am sure that the outward loop temp (ie. LWT) is higher than the return loop temp (ie. EWT). As the ClimateMaster does produce some air heat and lots of desuperheater water heat then there is something wrong.

    Can the loop pumps run backwards and could the refrigerent circuit half work when that happens? We have 2 geo-flo loop pumps.
     
  4. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Could be a simple lock-out (remedied by interupting the power briefly).
    If it has always acted up in the winter, it may not have been configured for open loop.
    j
     
  5. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Would not explain the DSH running hot.
     
  6. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    agreed, dunno that its plumbed right however, may be robbing heat from finish tank.
     
  7. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    OK guys

    What if the system is pumping into the source out side. I have yet to dissect a co-ax HX so I do not know if it would matter, but it could.

    Mark
     
  8. ant

    ant New Member

    Could the desuperheater steal all the available heat from the system? Put another way, if the ClimateMaster is labouring, should the desuperheater be automatically off?

    By the way, my system has a closed loop.
     
  9. Calladrilling

    Calladrilling Member Industry Professional Forum Leader

    Are you showing only a difference of 1 degree between ewt and lwt??
     
  10. Calladrilling

    Calladrilling Member Industry Professional Forum Leader

    Are you showing only a difference of 1 degree between ewt and lwt??
     
  11. ant

    ant New Member

    I'm showing about a 2F difference between the the in and out whenever the system is running and hover around 56-60F. These readings are taken against the outside of the loop pipes under the insulation. I checked the calibration of my probes this evening with freezing water and hot water and they are about right and show the same temp to withn half a degree (F). Also our system has always struggled in the coldest part of the winter. Sadly the first year it took me too long to realise that the pumps were actually cutting out. When I spoke to the installer, they said it was the "freezing protection" which we didnt need as it was a closed loop with antifreeze. They disabled it and the pumps never cut out again. Then the weather warmed up and that was the end of the installation support. This is the first year Ive measured the loop temperatures but as the loop temps never drop very much I wonder if that was the real problem but I dont know. The winter is milder this year.
     
  12. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    If the heatpump does not extract enough heat out of the source water, that means there is something wrong with your refrigerant circuit. Lack of refrigerant due to a leak would be first on my list.
     
  13. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Still not disagreeing with docs prognosis but would like you to turn off all breakers to heat pump and see if LWT changes in the next ten minutes.
     
  14. ant

    ant New Member

    Sure I can try that. Actually I turned off all the breakers yesterday for 10 mins to see if the system would "reset" but there was no behaviour change afterwards. During the poweroff the temperature slowly rises towards room temperature as the heat seeps through the insulation around the pipes.

    Exactly what should I turn off? I have 3 breakers - one is the aux heat, one the climateMaster and one is something else (I forget and Im not at home to look). I think the ground loop pumps power comes from inside the ClimateMaster but maybe that's just for control.
     
  15. ant

    ant New Member

    The 3 breakers are "geo compressor", "aux heat" and "funace cntl panel".
     
  16. ant

    ant New Member

    New sympton. Last night, and then again this morning, I found that the house temperature was falling and the loop pumps were off. I shut the whole system down, waited for 15 mins and restarted. The pumps restarted and the heating started again. Note that the desuperheater pipe was still hot even though the pumps were off. The aux heat on.

    So I'm going to call someone; any recommendations for the Rockville, Maryand area?
     
  17. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    "compressor" would be what you'd reset that unit with
     
  18. ant

    ant New Member

    When the pumps turn off this morning at 3:15am..... the LWT went from 58F to 60F in the first 10 mins and then to 61F in the next 10 mins.

    Feb 09 03:15:02 Sensor 0 C: 14.56 F: 58.21
    Feb 09 03:20:02 Sensor 0 C: 15.00 F: 59.00
    Feb 09 03:25:02 Sensor 0 C: 15.38 F: 59.67
    Feb 09 03:30:02 Sensor 0 C: 15.69 F: 60.24
    Feb 09 03:35:02 Sensor 0 C: 15.88 F: 60.58
    Feb 09 03:40:03 Sensor 0 C: 16.06 F: 60.91
    Feb 09 03:45:02 Sensor 0 C: 16.25 F: 61.25

    When the pumps stop normally it does the same thing.
     
  19. ant

    ant New Member

    I have more information. I opened the climatemaster up and looked at the DIP switches. SW12 was ON meaning that the desuperheater HWG is disabled. So the desuperheater is not running although the HWG pipe is too hot to hold. So I turned everything off, set SW12 to OFF (ie. turning the desuperheater on, after all I do have one) and restarted. Everything started after a delay and the compressor ran for about 2 minutes and then cut off. I put the CXM controllor into test mode and it told me that the error was FP1 "water coil low temperature". According to the manual, the cause is the thermistor is below the low temperature protection limit setting and the temperature is rising at less that 2F per 30 seconds. This check is disabled for 120 seconds. I turned everything off, disabled the desuperheater again, waited 15 mins and restarted. Everything is back the way it was.
     
  20. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    DSH is never shut off. The dip switch controls the circulation pump for the DSH.

    By the way, is your jumper cut? JW3

    If not it would show a FP1 fault code at your loop temps.
     

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