New geothermal install

Discussion in 'General Discussions' started by Nathanls14, Oct 11, 2019 at 12:06 PM.

  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,
  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.
    waterpirate likes this.
  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.

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