Kansas 2 ton vertical loop

Discussion in 'Maintenance and Troubleshooting' started by charr, May 30, 2015.

  1. arkie6

    arkie6 Active Member Forum Leader

    I would think that having those purge ports located at the very top of those loop pipes would be the most advantageous point to insure that all of the air is removed from the system.
  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Going from 6 to 5 gpm would make no meaningful difference, all what it does is that your leaving water temp in A/C mode is 1-2F degrees higher. You also might loose some turbulent flow, but the magnitude is really insignificant. The unit still puts pretty much the same amount of BTUS in the loop. In case there would be something wrong with the unit, it would reject less heat, not more, thus the fast swinging is not explained by that. It is not unusual for a vertical loop to go down to the low 30s quickly and then stabilize due to the phase change.

    The loop design describe I would consider more than accurate to support a 2 ton heat pump. So there are really only 3 possibilities:

    1) Everything is fine and you have incorrect reading due to effect of ambience temperature on the sensor
    2) No flow through 1 loop
    a) You have air in one loop.
    b) Your loop is kinked

    Now, assuming you have a single 25-85 pump, please confirm, which is the smaller pump, your pressure drop would be 19.5 ft hd giving you about 9.5 - 10 gpm with the 25-85 pump at full power. I would say you are far away from that.
    No lets say that one borehole is locked, and you are pushing all the flow through only one borehole, your pressure drop would be 27 ft hd at 5 gpm, and your pump could make a 27 ft at 5 gpm. A perfect match. If you have only 1 ft/hd higher pressure drop, you flow would go down to 3 gpm. The 25-85 is pretty much not performing anymore at those higher pressure drops. Looks to me that is what you are seeing.

    So it appears that all your flow goes down 1 borehole, and the other one is air locked/kinked etc. That would also explain the quick swings you are seeing. Is the loop field headered outside, or do the 3/4 pipes come in and are manifolded inside?

    And yes, you should have bought the unit through the same company as well.

    I would purge, and if that does not help dig up the header trench. But check the temps first with a needle thermometer.
  3. charr

    charr New Member

    Checked the temps with a meat thermometer we had and readings were very close to tstat. Will double check that this week but tstat seems okay. As for pump I will confirm on Monday but I think it is high head pressure 25-140. The book that came with my unit only showed the 25-140. The newer book shows a standard and high head but language seems to indicate my unit would be high head anyway. My unit was either late 2012 early 2013 and I don't think the model numbers even had a differentiating factor for pump on those units. They seem to now. What would a 25-140 do to those calculations? As for loop the only manifold is the one right by the unit inside. I posted a pic of it on one of the posts.

    Attached Files:

  4. arkie6

    arkie6 Active Member Forum Leader

    Page 6 of the May 2012 Climatemaster catalog states the following:

    "This internal loop circulator is the variable speed Grundfos Magna 25-140 for all TE30 units."

    The Grundfos Magna 25-140 pump curve is also provided and it shows it is capable of 47 to 48 ft hd at 4 to 6 gpm.


    Apparently, the low head pump only became available in later year models.

    The current Climatemaster TE 30 series catalog last updated Feb, 2015 lists both the "1" standard head pump "UPM Geo 25-85 Standard Head Variable Pump" and the "2" high head pump "Magna Geo 25-140 Pump" with pump curves shown for both.


    You can open the front of your unit and see which pump you have. The UPM Geo and Magna Geo pumps are different in appearance as per the Grundfos catalog below:

    http://net.grundfos.com/doc/webnet/hvacoem/pdf/The new OEM Circulator Range U.S.pdf
    Last edited: Jun 7, 2015
  5. charr

    charr New Member

    It is that magna geo pump so the high head one. Model number in attachment.

    Attached Files:

  6. arkie6

    arkie6 Active Member Forum Leader

    Based on one of your photos that shows the communicating thermostat (I've thus far been avoiding opening attached your files because they are so unnecessarily large and I have a slow internet connection), it provides the following regarding the pump:

    Pump Watts 143
    Flow Rate GPM 4.3
    Pump Speed 81%

    Looking at the Grundos pump energy consumption curve, the pump should consume ~175 W max at around 4 GPM, so you are not too far from pump maximum output (~82% of max output as also indicated by the pump speed). With two 3/4" x 400' loops in parallel (they are piped in parallel correct?) and connected to the pump with <200' of 1-1/4" pipe, that pump should be easily move 4.3 GPM through that loop at less than 50% rated power.

    I'm betting that one of your 3/4" loops is blocked either due to a large air bubble at the top of the loop or the pipe was crushed/kinked during or after install. Have you had any heavy equipment near the wells or lines running to the house?
    Last edited: Jun 8, 2015
  7. arkie6

    arkie6 Active Member Forum Leader

    What is he using to flush the loop? That 2 psi pressure drop is meaningless without knowing the flow rate.
    Palace GeoThermal likes this.
  8. charr

    charr New Member

    Did not know pics were taking up that much size. The only heavy equipment after loops were drilled was same company's excavator for header pit work. If I understand the question correct the loop from the house to first hole and then to second is about 110 to 120 degree angle. Loop was flushed with a 90 psi max flush cart. The book does say use at least 100 so perhaps that could be issue. Should 90 psi get the job done?
  9. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    GPM on the flush cart is more important than PSI. The minimum velocity for flushing is 2 feet per second, and the flushing should be done both ways through the loop.
  10. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    with the Magna 25-140 pump it is much uglier. It should move at least 10 gpm at 80%, but it only moves about 6 gpm. You have some sort of flow restriction in your loop, either air or kinked pipe (or other rarity, like a sharp edged rock on it, can't really think about anything else). 90 PSI are fine,. It is not the pressure but the flow rate it can achieve. If a flush cart could not do it in the past, my vote moves out of the "air lock" category and into the "kinked loop". You have to dig up the header pipe where it Ts off to each borehole and see how much flow you can get through each. Or something else is blocking the flow. Stones, debris. Or your pump is faulty and not pumping right. But unlikely given that your loop swings that much, which suggests a partial locked loop.

    Fact is, you don't seem to have enough flow through your loop field, and your high temp swings suggest that only only one borehole sees water flowing through it.
  11. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    I agree. At this point the diagnostic indicates digging up the header pit and flow testing each loop independently. I once had a stone stuck in the u-bend, I am guessing as flow testing was like nite and day for 1 loop in the field.
  12. gijoe

    gijoe New Member

    Whoever performs the flushing of this unit should be aware that, unlike external flow centers, flushing can only be done in one direction.
    From the manual:

    "Units with internal variable speed pumps also include a
    check valve internal to the pump. It is not possible to flush
    backwards through this pump. Care must be taken to
    connect the flush cart hoses so that the flush cart discharge is
    connected to the “water in” flushing valve of the heat pump."

    The fact that your psi has dropped in the loops suggests 1)air in loop or 2)the internal expansion tank was not used or set-up properly. #2 suggests lack of familiarity with this heat pump by the installing contractor (if that was in fact the case). If a contractor is not familiar with these models and does the same process used on other/older models, it could easily lead to flushing/purging issues.

Share This Page