New geothermal install

Discussion in 'General Discussions' started by Nathanls14, Oct 11, 2019.

  1. Nathanls14

    Nathanls14 New Member

    Hi all, been a reader for a while as I had been toying with the thought of going geothermal (currently on a 22 year old 90% efficient LP furnace and an 8 year old R22 AC). This past weekend I took the plunge and they started the install which I have 2 questions on.

    I have a 2400sq ft ranch style home and the basement is 70% finished (I have all vents turned off in the basement as it stays at relatively stable temps year round). A manual J was done and came out to needing a 4 ton loop field/Geo unit. The 4 wells that were dug are vertical down to 155ft each connected in parallel.

    My first question is, I have 2 pumps installed for the loop field in a push/pull configuration and was wondering if that is overkill for my install. The pumps are both groundfos 116s.

    My second question is, I currently have 5 wire ran to the thermostat (I have an ecobee3). Would it make more sense to rerun the wire to make better use of the dual stage furnace (EL296UHV), which also has a separate hookup on the board for better dehumidification in the summer when the AC is running (I've read that this gets hooked to the ACC+ on the ecobee)The tech said they can set the dip switches for the dual stage to run off of a timer and if it's not satisfied within X amount of time then the second stage would kick on. Also, if I'm not mistaken, I believe I read that the waterfunace series 5 is also dual stage as well. With wanting to use the Geo unit to heat/cool, should I even bother with setting up the dual stage through the ecobee or the extra dehumidification process?

    Just trying to stay as informed as possible and make sure I get the best bang for the buck. Let me know what additional details you may need to help!

    Thanks for the help,
    Nathan
     
  2. ChrisJ

    ChrisJ Active Member Forum Leader

    WF 5 series is dual stage. I believe most 2 stage HP's up stage when the temp drops 1 or 2 degrees below set point.

    The 2 @ 26-116's is over kill and those are the least efficient pumps, depending on how the loop field is configured, should be using a single 26-99 grundfos.
     
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  3. Nathanls14

    Nathanls14 New Member

    So I don't need to worry about hooking up the 2 separate stages from my ecobee for the Geo unit. Should I still consider hooking up the 2 separate stages for the backup furnace, it will only be used when the Geo unit can't supply enough heat. I should've mentioned that I have a split system, 96% efficient furnace on LP for backup heat and the waterfunace 5 split.

    I was afraid of that answer about the pumps. What's the determining factor on whether a single 26-99 would work for my setup? What specs would you guys need to know?
     
  4. wing

    wing Member

    get onto the geoflow design calculator and derive a head vs. flow rate curve for your loop field/ heat pump piping.

    from there overlay with the pump curve(s) from the grundfos site.

    you'll have your answer then.
     
  5. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    you still need a 2 stage thermostat hooked up with a dual stage heat pump, you can use the 3rd stage to turn on your furnace

    26-116 pumps are efficiency killers and do not add much pumping power.

    I would go as far as saying that they should not be installed in a modern geo system

    Dual stage on a timer? Silly! Your thermostat should do that
     
  6. Nathanls14

    Nathanls14 New Member

    I ended up having the install company rerun 8 wire to my thermostat. I have it set up for dual stage Y1 and Y2, only single stage backup with LP to W1 (I could jump W1 to W2 so it runs dual stage when backup is called), and also ran the accessory wire ACC+ for the dehumidification cycle on the furnace for the summer. I've had a hell of a time with the install company, they only had Y2 hooked up originally so nothing happened with stage 1 outside of the furnace fan coming on and the connection from the flow center to the waterfunace5 were never tightened fully and leaked while running. They are coming back next Friday to walk through everything, although I've fixed it all.

    I've had several people tell me that the 116 is overkill and inefficient, let alone dual pumps. Seeing as it's already installed, would I have any issues if I unhooked the power to one of the pumps and ran with a single pump? When that one pump fails then I have a spare? Thoughts/suggestions?
     
  7. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Pump guys do not recommend to pump through a de-active pump. High pressure drop, too (flow restriction). There are caps available to take out one pump, you are still being stuck with 1 inefficient pump. Can't you ask the installation company to take back the flow center and put a single pump 26-99 in? Or even better a inverter driven pump?
     
  8. Nathanls14

    Nathanls14 New Member

    Doc, appreciate you chiming in on this post and Wing appreciate the help you gave me with the flow rate curves.

    I ended up buying a blank off plate and took one of the 116s out of my flow center. Interesting thing is that both pumps were only pulling 2.6 amps vs 3.6 and with one single pump it was only pulling 1.2 amps so I am actually close to the wattage of a 99 (unless my brand new fluke meter is incorrect).

    Anyway, I wanted to post some before/after stats, and get some comments if you see any issues (I don't personally see any but I'm brand new to this so what do I know). I also want to ensure I am pulling the info correctly as well as calculating my stats correctly. I have 3 separate sets of stats, one from the tech, and 2 from me. Mine will be at full and part load so stage 1/2 while the tech's will only be stage 2.

    I do have a question with regards to SEER and COP calculations. In the WF manual it states that SEER is Capacity/watts while another site I found states ((Temp Delta * GPM * 60 * 8.35)-(Watts * .85 * 3.412))/watts. Depending on which calculation I use, the WF calculation always comes in lower. I've posted both results below. Which should I use and which is more accurate? Also, do I include the wattage from the furnace in the SEER/COP calculations, currently I am not?

    Measured by tech during walkthrough
    Stage 2
    Heating:

    EWT - 55
    LWT - 52
    PSI In - 25
    PSI Out - 18
    GPM - 18 (Calculated based on WF5 table which doesn't go high enough so it's estimated)
    Volts - 242
    Amps - 14.6

    Cooling:
    EWT - 57
    LWT - 62
    PSI In - 35
    PSI Out - 25
    GPM - 21 (same issue as above)
    Volts - 243
    Amps - 12.25

    Based on the above info I calculated:
    Heat of Rejection/Extraction - Cool - 50,925 & Heat - 26,190
    Capacity - Cool - 42,289 & Heat - 36,440
    Efficiency WF - Cool SEER - 16.7 & Heat COP - 3.6
    Efficiency Web - Cool SEER - 17.9 & Heat COP - 4.1

    Before (with 2 116 pumps in flow center)
    Stage 1
    Heating:

    EWT - 47
    LWT - 45
    PSI In - 33
    PSI Out - 26
    GPM - 18 (Calculated based on WF5 table which doesn't go high enough so it's estimated)
    Volts - 242
    Amps - 11.6

    Cooling:
    EWT - 57
    LWT - 61
    PSI In - 34
    PSI Out - 26
    GPM - 19 (same issue as above)
    Volts - 239.6
    Amps - 9.4

    Based on the above info I calculated:
    Heat of Rejection/Extraction - Cool - 37,684 & Heat - 18,333
    Capacity - Cool - 31,150 & Heat - 26,477
    Efficiency WF - Cool SEER - 16.3 & Heat COP - 3.3
    Efficiency Web - Cool SEER - 17.4 & Heat COP - 3.7

    Stage 2
    Heating:

    EWT - 45
    LWT - 42
    PSI In - 34
    PSI Out - 27
    GPM - 17 (Calculated based on WF5 table which doesn't go high enough so it's estimated)
    Volts - 240
    Amps - 13.8 (0.8 amps less than what the tech read)

    Cooling:
    EWT - 52
    LWT - 59
    PSI In - 35
    PSI Out - 28
    GPM - 18 (same issue as above)
    Volts - 239.6
    Amps - 11.6 (0.6 amps less than what the tech read)

    Based on the above info I calculated:
    Heat of Rejection/Extraction - Cool - 58,491 & Heat - 23,910
    Capacity - Cool - 50,428 & Heat - 33,519
    Efficiency WF - Cool SEER - 21.3 & Heat COP - 3.5 (it's interesting that my SEER and COP is better in stage 2 than stage 1, did I not wait long enough before taking readings?)
    Efficiency Web - Cool SEER - 22.7 & Heat COP - 4.0

    After(with 1 116 pump in flow center)
    Stage 1
    Heating:

    EWT - 50
    LWT - 47
    PSI In - 33
    PSI Out - 28
    GPM - 14
    Volts - 237.6
    Amps - 10.1

    Cooling:
    EWT - 50
    LWT - 59
    PSI In - 39
    PSI Out - 35
    GPM - 13
    Volts - 241.7
    Amps - 7.8

    Based on the above info I calculated:
    Heat of Rejection/Extraction - Cool - 50,319 & Heat - 21,049
    Capacity - Cool - 44,850 & Heat - 28,011
    Efficiency WF - Cool SEER - 28.0 & Heat COP - 4.0
    Efficiency Web - Cool SEER - 29.5 & Heat COP - 4.7

    Stage 2
    Heating:

    EWT - 49
    LWT - 45
    PSI In - 32
    PSI Out - 28
    GPM - 12
    Volts - 240.7
    Amps - 12.2

    Cooling:
    EWT - 55
    LWT - 64
    PSI In - 38
    PSI Out - 34
    GPM - 12
    Volts - 244
    Amps - 10.4

    Based on the above info I calculated:
    Heat of Rejection/Extraction - Cool - 52,380 & Heat - 23,280
    Capacity - Cool - 45,018 & Heat - 31,799
    Efficiency WF - Cool SEER - 20.9 & Heat COP - 3.7
    Efficiency Web - Cool SEER - 22.2 & Heat COP - 4.3

    Ductwork Temp Diff:
    Tech Heat Supply - 67 Return - 89
    Tech Cool Supply - 66 Return - 42
    2 pumps Heat Supply - 66 Return - 87
    2 pumps Cool Supply - 66 Return - 39
    1 pump Heat Supply - 66 Return - 86
    1 pump Cool Supply - 66 Return - 38

    There really was no difference in any of the ductwork readings between mine and the tech's, or stage 1/2 with 1 or 2 pumps. My assumption with Stage 2 vs Stage 1 is that the temp stays similar but the CFM of air through the house is higher thus heating/cooling faster is that accurate?

    All in all, it's been an experience to say the least, and I appreciate everyone's input as well as the knowledge of this board as that is what I used to leverage info for the install. Looking forward to any comments, thanks again.
     
  9. wing

    wing Member

    I include here the loop supply and pump curves based on loop configuration parameters supplied by Nathanis14. Loop curves were calculated using the Geoflow on line calculator and the pump curves are directly from the Grundfos web site. Noted that the installer ‘always includes two 116-99 pumps in series’ for a four ton heat pump build.

    These are the theoretical curves for a single 116-99 pump. The projected 14.5 gpm loop flow rate closely matches what the user saw on the actual installation. Two 116-99 in series would have been overkill for this setup.


    9459FE88-D2A2-4897-9DAC-70B728795C22.png


    Docjenser notes that 116-99 pumps are efficiency hogs and have little value in a residential installation. So this next set of curves is a ‘what if’ in the case the more common Grunddos 26-99 pump was used instead. And indeed, the 26-99 is plenty of pump for this loop configuration. Nathanis14 is likely using the 116-99 as that is what he had on hand for his system.


    3E8C79FA-D34F-4837-A512-66B4A4FC8DCD.png




    This stuff actually works !
     
  10. David Maynard

    David Maynard Renewable

    Nathan, with regards to the loop pumps I would strongly recommend a flow center as they offer easier servicing and flushing. If you decide to use individual pumps, I would suggest consulting the pump sizing calculator on http://calculators.geo-flo.com/pump-sizing . You will need to create a login but the software is great, in my estimation.
     
  11. Nathanls14

    Nathanls14 New Member

    I do in fact have a flow center The flow center was installed with 2 26-116 pumps and working with Wing it was determined that I could get by with 1 26-116 pump (ideally I should be able to get by with 1 26-99 pump based on his calculations). The flow center made it very easy to take out one of the pumps, apply a blank off plate and bleed the air that in introduced in to the loop. I also took before and after readings which I posted above to get some feedback and ensure that there is nothing else anyone sees that looks out of place.
     
  12. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Your numbers look good.

    The point is that you pulling significantly lesser amps without any significant difference in capacity, thus you have a better COP and EER.

    The heap pump's capacity is only minimally influenced by lesser water flow, however, you cut your pumping power in half. I use usually only 2.25 gpm/ton. I go the extra mile and use always variable speed circulator pumps, with average power usage over the season being 92 watts. I also dial down the blower for lesser noise and lesser power draw. It increases the compressor wattage slightly, but overall it increases the efficiency of the whole system by 12-15 %.
     
  13. Nathanls14

    Nathanls14 New Member

    Doc, appreciate the reply. For my 2 stage furnace I believe stage 1 is set to 70% blower speed which draws roughly 1.6 amps while stage 2 is 100% and draws 4 amps and does increase sound substantially. I can control the speeds via dip switches but have not gotten that far yet, any particular recommendations for stage 2 speed?

    When I calculate my COP and EER, should I include blower watts as well? I have a split system so I wasn't sure if that should be included or not as an all in one system would include it would it not?

    Which circulation pump do you typically use and how does the system know what speed to run the pump at?
     
  14. David Maynard

    David Maynard Renewable

    I'm not sure about the blower watts for COP calculations.
    The variable speed Geo-Link flow centers will require communicating controls with Waterfurnace products to communicate pump speed, which is set up with the AID tool.
     
  15. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Blower and pumping watts need to be included in the COP calculations.

    You cannot ignore the parasitic energy losses of the accessories.
     

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