South Dakota New to Geothermal, have some general questions

Discussion in 'Maintenance and Troubleshooting' started by MicaTurtle, Sep 18, 2020.

  1. MicaTurtle

    MicaTurtle New Member

    Hi all,
    I recently bought a house that has a Geothermal system that was installed in 1998 (when it was first built), that came with no manuals or any type of documentation that I can find, and let me tell you, it's a been a crash course in HVAC learning compared to my old "normal" electric AC and gas furnace. While trying to familiarize myself with my system (something I like to do BEFORE something goes wrong, so that I don't get seen as an easy mark by repairmen) I've come into some questions.

    1. Is a Geothermal system and "heat pump system" the same thing? Are there any other HVAC systems that use heat pumps?

    2. What is the difference between the a closed loop and an open loop system?

    3. I'm assuming the reason that coolant is used most of the time instead of just water is because in places like where I live (South Dakota), water could freeze and rupture pipes? Is that correct or is there a different reason?

    4. I think I'm correct that all Geothermal units are "ground source" (meaning that they take heat or cooling from underground) However, how can I tell if I have a "direct exchange" (it just pumps coolant around thru the ground) or a "water source" (it pumps water down into pipes interwoven with the coolant pipes) system? (If I'm wrong with any of my definitions, PLEASE let me know)

    5. If a certain manufacturing company has their logo emblazoned on the large metal box in the basement (in my case, FHP Energy Systems), does this mean they probably made the whole system, including the box (I think it may be called a cabinet), the pipes to the underground, and the heat pump? Or is it normal to piecemeal system parts out to whomever installers/contractors can get the best deal from?

    6. My serial number on the sticker on the side of the metal box thing in my basement says "FHP Manufacturing Division", and has a serial number that starts with an EJ ... I know it's manufacture date is in 1998 because of this page - - However, it has the a model # of GT026-1VTN, as well as a model # of HP100-1XS (on a different sticker) - Which one is the model number for which part?

    7. I think I have R-22 refrigerant/coolant running thru the pipes of my system, I know that they recently outlawed the production of NEW R-22, and that eventually I'll have to flush all the old stuff out and replace it with an alternate coolant. Does anyone know how to tell how many gallons of coolant are in your system? and/or approx. how much it will cost to have it replaced eventually?

    Thanks for this site, and for all the information it provides.
  2. gsmith22

    gsmith22 Member

    1. geothermal system is probably better called a "ground source heat pump system" which would have pointed you in the right direction that they are in fact heat pumps. It extracts heat from the ground (heating) or rejects heat to the ground (air conditioning) via the water based ground loop. At the inside of the house, it distributes heat via air (forced hot air or a/c) or water (radiant).

    2. closed loops is just that - a fixed amount of water is pushed through the system between the heat exchanger in the heat pump out to the heat exchanger in the ground. An open loop system extracts water from an exterior source (typically an underground aquifer) runs it through the heat exchanger and then puts it back to the exterior source. the water drawn in is not the same water that the system is rejecting to the ground.

    3. antifreeze is used in closed loop systems only to prevent the loop from freezing and not being able to circulate the water. loop temps commonly drop to ~30F during heating season

    4. yes - see #1. Direct exchange wouldn't have hdpe pipes carrying water. I believe they take the condenser coil and run it into the ground so refrigerant is directly exchanging heat with the ground instead of a water loop. Water based geo system have several heat exchangers inside of them to transfer heat between the ground loop, refrigerant loop, and method of heating/cooling the house.

    5. they would have made the box only which contains the heat pump. ground loop is constructed on site piecemeal (which is why the systems are expensive to build). I would guess they probably didn't make any loop pumps used to circulate the water in the ground loop.

    6. not familiar - hopefully someone else will chime in who is

    7. every heat pump I have ever seen tells you how much refrigerant is in the heat pump on the unit label. BUT, I think you will find that a replacement unit will be your best and cheapest route. Significant efficiency gains have been made since 1998 not to mention the likelihood that current refrigerants won't run the system or at least run it well. If you are going to get a new unit, do it now. Federal tax credit is 26% this year, 22% in 2021, and then disappears after that.
    MicaTurtle likes this.

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