Match Well to Geothermal efficiency

Discussion in 'Solar and Geothermal Water Heating Forum' started by harleyhf, Dec 10, 2009.

  1. harleyhf

    harleyhf New Member

    Dec 9, 2009
    La Porte Indiana
    Need advise to size well to 5 ton 2-stage Geothermal Heat Pump. HP demands 7gpm at 1st stage everyday use and 15 gpm at 2nd state initial or high demand. 2 stages accomplished by dual solenoid flow valves on outlet of HP responding to calls from multi-stage White-Rodgers 90 series HP Tstat. This is a 2600 sq ft Lake house in Chicagoland area, eighteen feet from seawall, but lake level and watertable fluctuates 10-20 feet over 20-50yrs and iDNR would threaten if I pipe year-round a 1-1/4 inlet line into the lake and run a jet pump, so 4" well is acceptable solution. Soil is sandy loam and most wells in region are 65-70 ft deep, with one 130 ft. Well will be 30ft from home. Geothermal unit is below ground at lake level.

    4" well spec'd and yesterday the prospective well driller got adamant with me after I questioned his singular decision to spec me a $4000 65ft install with Grundfros 22 SQE Variable speed pump in event I want to water the lawn or find other uses for well. Yes I would love add'l capacity but appears it defeats the savings of the GSHP efficiency and my drinking water has to be City Water by ordinance. (For summer use I will continue to drag the jetpump out and water the lawn separately) Regarding Grundfos SQE selection, I was very concerned as I heard reports of short 2-5 yr life, but well driller told me he has been installing Grundfros for 13 years and only twice has had SQ failure and Grundfros took care of it under warranty. He suggested I call Heat Controller OEM and get their view which was same as his - VSP for Constant pressure. My concern remains pump life and efficiency to justify my very expensive decision to GSHT. Blog-lurking tends to tell me 'size pump to 15 gpm GSHP need for efficiency and low pressure from selected pump required, finishing installation with 5gal tank and Cycle Control Valve for constant pressure and pump life, cycling, and cooling'. My questions here include (I don't know what I should look at to see the amps at 5gpm versus rated 15 gpm capacity at well depth or to get low pressure related to gpm flow needed) what brand & model pump would you suggest that would meet my flow requirements, yet when GSHP is idle, would "amp down" significantly for energy savings with the 5gpm bypass in the CSV? As sandy, what pump is durable in presence of sand? And in area with minerals reported, which pump is durable in avoiding failure from hard water (reports of stainless steel Grunfros failure due to imbalance from hard water deposits on impeller shaking it apart was made to me by another Grundfros well installer whereas he claimed plastic impellers were more resistant to failure from hard water deposits) Appreciate your insight and experience in separating the 'wheat from the chaff'. Any other suggestions I should be considering as I go well driller shopping for Geothermal only application?
  2. nhmaster

    nhmaster Master Plumber

    Jul 30, 2008
    Tech. Instructor
    S. Maine
    Stay the hell away from any variable speed water pump. They are expensive and they do not last.
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  4. harleyhf

    harleyhf New Member

    Dec 9, 2009
    La Porte Indiana
    1hp 2-wire Gould, Myers, or Schaefer for Geothermal/Whole Hse

    Thanks for reply on VSP for Constant Pressure - right there with you.

    What can helpful seasoned veterans comment - Comparing the Myers, Gould, and Shaefer Submersible lines for my Geothermal Pump application 15gpm (with highly probable later addition of 10gpm house water)? [Performance, efficiency, long life]

    Here is what I am getting back from well drillers licensed in my area-

    1a. Geothermal for now - had one well supplier quote 1hp Myers 20gpm with WX251 Tank & CSV1Z for Well at 70ft for $3185 and another quote same but with WX102 Tank for $3200 (huh?).
    1b. Geothermal forever - Another quote 0.5hp Shaefer 15gpm at 10psi (we are on Lake, nearly at lake level) with CSV1Z at 70ft for $3300

    2a. Submersible and Booster Pump design as seen at "Two Pump Geothermal System" with 1hp Myers, two WX102 Tanks, 3/4Booster & Control Box, CSV1W on Booster for 50psi and CSV1Z for Geothermal for 20psi at 70ft for $4300
    2b. Awaiting quote from Shaefer well driller

    Is there any opinion on performance, durability/life, and "energy efficiency by high-demand versus low-demand amperage consumed" on Myers versus Schaefer versus Goulds for 4" submersible in 1hp 2-wire catagory for my geothermal/whole house split application with 3/4hp booster pump? Sorry for length of post, trying to narrow the purchase as its C-O-L-D out there and I'd like to make an informed decision since I hope it is a 15-20 yr purchase.
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