horizonal Summer loop temps.

Discussion in 'Vertical and Horizontal Loops' started by SolarPower, Jun 19, 2019.

  1. SolarPower

    SolarPower Member

    I have a 3 ton system with 4 loops 600 foot each.

    Two 300’ trenches 3’ wide 6’ deep loops go out then up two foot them back.

    This is our first summer with geothermal we are in the south just outside Greenville SC ground temp 6’ down about 56 degrees.

    We started out the summer with a couple week heat wave some days were 98-99 degrees.

    The system did great and never had to kick on stage 2 until it is around 96 outside.

    My loop temp cools some over night and now it is getting up to about 80 degrees.

    LWT-EWT is about 9.1 degrees difference.


    I have one pump Grundfos UP2699FC pressurized system and have set it to medium for the summer.

    I guess I was wondering if loop temp 80 degrees was normal. It seemed to go pretty quick from winter loop temp to summer loop temp.

    Yes, we did have a heat wave for a couple weeks. I just have nothing to compare it to all the public data for loops I could find were in the northern part of the country.

    They might just start using AC.

    It is working really well the house is very comfortable and the humidity is being controlled well. We have solar power banked 1,000 KWH to use this winter for heat.

    Is there a loop temp that I should be concerned with? I guess I expected the loop to stay cooler than 80 degrees at this point in the summer. But I have nothing to base this on other than knowing the ground temp at 6'.

    Other horizontal loop systems in the south what are your loop temps?
    Last edited: Jun 19, 2019
  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    56F is pretty low for SC, we are looking at 59F in the NYC area.

    It is a bit early to say, nothing bad is gonna happen if th etmnep will go up to 100F or 110F. Just a bit less efficient cooling.
  3. SolarPower

    SolarPower Member

    Thanks for the reply.
    I looked at some of your systems you have online very nice to see systems loop temps online.

    I found this on a South Carolina Geo installers web site.
    Average ground temperatures in the Carolina's are between 60 and 65

    Seeing what temp you have in NYC this seems a lot closer to being correct here.
    That would make a lot more sense to what loop temps I am seeing.
    Last edited: Jun 20, 2019
  4. ChrisJ

    ChrisJ Active Member Forum Leader

    The 9.1* Delta T seems a little high. I would try the pump on high see if it comes down a bit.

    How is the electric use compared to the mini-splits?
  5. SolarPower

    SolarPower Member

    I just set it back to high. I thought a higher Delta was preferred.

    If I compare it to the old natural gas heat and the old AC unit we are doing great.

    Comparing it to the mini splits is much harder.

    The mini splits did not directly cool the bathrooms, laundry room and one small office/bedroom.

    It is really hard to compare right now we have more solar banked than last year. But my son has his own car and we are driving our EV less.

    I have an energy monitor on the Geo but I did not have one on the four mini splits. My bedroom mini splits were 27 seer.

    The geo system is using 1.8-1.75 kw when running. My gut feeling is that there are some savings over mini splits but it is not a huge difference.

    Our home is more conformable and the small bedroom my father-in-law stays in sometimes is now heated and air-conditioned this is a big win.

    Humidity is controlled a little better.

    I have no hard numbers for this and no easy way to show them.
    Last edited: Jun 21, 2019
  6. ChrisJ

    ChrisJ Active Member Forum Leader

    You know your home...More comfort is a plus.

    See if changing speed has any affect on EWT.
  7. SolarPower

    SolarPower Member

    Here it is on high not really that different 8.1 delta T


    I did look back on my electricity bills and this year I have banked 37 kw solar more than last year at this time.

    That is about $4 difference. I also saved $4.86 in hot water. $8.86 saved I can now buy a burger.

    I knew this would not be a big money savings. Mini splits are supper efficient and they paid for them self’s in savings.

    They are really great in the summer.

    We are not disappointed at all. Geo keeps the whole house more comfortable. Each room in the house is a much closer to the same temp.
    Last edited: Jun 23, 2019

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