South Dakota Question on water temps

Discussion in 'Maintenance and Troubleshooting' started by ff42, Mar 2, 2015.

  1. ff42

    ff42 New Member

    I have a Bard 4 ton single stage groung source heat pump with 4 200 ft verticle bore holes. In the winter, my incoming water temp is in the low 60's and outgoing is in the low 30's. Unit is flowing 11 gpm. Had my hvac contractor switch thermometers on the incoming and outgoing water lines and nothing changed. He said that I must have a warm spot underneath my front yard where the bore holes are. It has been like this since January of 2009 when the system was started up. The summer temps are coming in at low 50's and going out at low 60's. In the winter, the air temp leaving the unit is 88 degrees. The air coming into the unit from the cold air return is at 70 degrees. Unit seems to be running fine and using only minimal auxilliary heat when temps get to 20 below zero. My question is are these winter loop temps normal? If more information is needed, I will do my best to get it.
  2. pfer10

    pfer10 Member

    It sounds like your unit is running okay but something is wrong with the numbers. According to your numbers with a delta of 30F you're pulling over 160kBTu from the ground. That would be pretty hard to do with a 4 ton unit.

    The summer entering temp should be higher than the winter entering temp. Did you mis-type the 60 entering temp?
    Palace GeoThermal likes this.
  3. ff42

    ff42 New Member

    Just checked the temps again and incoming is 61 outgoing is 29. The temp outside is 34 above zero and pretty windy. Summer temp wasn't a typo although they are a lot closer together than the winter temps. Will talk to my hvac guy this weekend at the home show. Any particular question I should ask? Thanks in advance.
  4. pfer10

    pfer10 Member

    How did you check your flow? A 4 ton unit should extract ~42k from the loop. At a 32F delta that is only 2.6GPM for 42K BTU. If those temps are correct then the flow has to be wrong.

    There is something wrong somewhere. Not saying your unit is performing wrong as 18F delta on the the air side is right. Since your entering temp is 60 your loop is performaning very well. That is better entering temps than open loops. Do you have hot springs in your area?
  5. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    I have never heard of a heat pump that drops the EWT 30°. I am not sure that is even possible. This is really strange
  6. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I thought that too.

    Old guys see numbers as relationships.

    This is does not ring true.

  7. Tamar

    Tamar Member Forum Leader

    Where and how is the EWT being measured? PT port at the unit or some other way?
  8. ff42

    ff42 New Member

    I have a clear tube that measures flow. I am looking at it and it reads 11 gpm at the top of the float. That's where it says to check it. Not sure if there are any hot springs around here.
  9. ff42

    ff42 New Member

    Thermometers are not measuring at the unit. They are inline with the pipe coming into and going out of the unit. The brand of thermometers are Weiss. They are solar/digital thermometers. Can I measure temp at the unit? If so, how?
    Last edited: Mar 3, 2015
  10. ff42

    ff42 New Member

    I will talk to my hvac guy this weekend. My bills have not been out of line at all. January was fairly cold and the heat portion of my bill was $99 for the month. That's heating 3400sf of a ranch house with finished basement. The unit also has a de superheater and there is a fan tech HRV hooked up also. Not sure if that will make any difference.
    Last edited: Mar 3, 2015
  11. Tamar

    Tamar Member Forum Leader

    How close to the unit?
  12. ff42

    ff42 New Member

    They are both about 3 ft away.
  13. mtrentw

    mtrentw Active Member Industry Professional Forum Leader

    A picture would be worth a thousand words. It is clear that the incoming temp is not correct. The heat extraction noted is a physical impossibility and it simply defies logic that the EWT in winter is 10 degrees warmer than in summer.
    1. Bad thermometer.
    2. Solar Digital Thermometer experiencing some sort of interference.
    3. Perhaps an area of stagnant water that the incoming thermometer is reading, thus it stays near ambient room conditions (is there a piping arrangement or shutoff valve near the thermometer which would cause this)
    4. Improper insertion of thermometer in the temperature well.

    Maybe swap the two thermometers as a first step?
  14. pfer10

    pfer10 Member

    I bet your EWT is actually ~37or38.
  15. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Your numbers are off, they simply do not add up.
    Either your flow is off, or your temp (EWT) is off. It does not matter if your garden has a hot spot. Your installer should have been suspicious. The delta T is in and out the heatpump. What you are describing is physically impossible.

    Also your EWT in south Dakota with your loop length and building load should be around 30-35F right now, check your thermometer.
  16. ff42

    ff42 New Member

    Hvac guy already swapped them. The temp does move several degrees if the unit hasn't run in awhile. I can feel the fluid in the sight tube of the flow meter and it does feel pretty warm. The temp in the mechanical room is 70 degrees. Shut off valve is 3 feet away from thermometer. In the summer, the temp difference is about 6-8 degrees.
    Last edited: Mar 3, 2015
  17. ff42

    ff42 New Member

    Ok. I'll ask my hvac guy this weekend.

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