Maryland Trane GSUF060 geothermal heatpump performance

Discussion in 'Maintenance and Troubleshooting' started by officeguy, Oct 20, 2015.

  1. officeguy

    officeguy New Member

    I just closed on a home that has a 2001 vintage 5Ton Trane GSUF060 heat-pump hooked up to vertical loops. During my walk-through a couple of days before the closing, I found that the heat output of the system wasn't sufficient to raise the temperature of the home without kicking the heat-strips on.

    The differential between the return and the main output was about 13F. Upon further investigation, it turned out that one of the Grundfoss pumps on the pump module wasn't running due to a wire-nut that had backed off. Also, the 'IN' and 'OUT' connections on the loop side of the system had been switched during installation.

    After getting the second pump online, the differential increased to 16-18F in heating mode. The sellers contractor has the hose kits on order to switch the loop to the correct configuration and I have a holdback on the purchase price that covers potential repairs.

    Now I am looking for a data source that tells what this system is supposed to put out. Trane has been less than helpful. The sellers contractor tells me that 'it's supposed to do that' [​IMG] The only manual I can find from Trane is a generic users manual that doesn't have performance tables. So if someone has experience with this particular system, could you please give me some pointers towards:

    - what GPM flow does this unit require on the loop side ?
    - what temp differential should I see on the loop side ?
    - what temp differential should I see in heating mode on the air side if my return is around 70F ?
  2. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I need a road trip, I'll come fix it for you.

    The reason you can not get info out of Trane is they have none. The engineering happens at American Standard.

    The manufactures all use the same stuff so this should be easy.

    Loop side GPM should be around 3 per ton. R-12, R-22, or R-410A, should all be the same even some big commercial type refrigerants the same. What we are looking at is how to move the heat from the lawn into the house, all close enough to be called the same GPM.

    The loop side delta T can very. I would have you go find a manufacturer with open engineering files and interpolate. One needs to look at EWT and LWT plus EAT and LAT. Then look at any ones tables for the refrigerant your unit uses and make a SWAG. I am going to add delta T rise through the air coil now because all these numbers are a moving target.

    The reason it is so easy to build a bad geo or air transfer heat pump is that the numbers move while you watch them for testing.

    As a unit runs on start up the IAT is maybe 55* F. The loop has never run and sends in 75* EWT. The system has run for an hour while you run around and take all the numbers. After that hour the IAT or EAT is now 62* and after an hour of run time the loops are EWT at 68*. As we start into hour two of operation, the home is up to 62* and the loops are down to 70* .

    I started fooling with Geo when we ran out of natural gas,when Jimmy Carter was President. God's speed, Jimmy.

    It has taken me this long to get the thermal transfer and apply it well.

  3. officeguy

    officeguy New Member

    Thanks. I know my question is lacking a lot of the necessary detail. The thing is, those units didn't come with all the built in diagnostics. It has the two ports on the loop side to measure temps and pressures, but you have to tabulate it yourself. Right now, I am not heating the house, so I dont really know what the steady-state is going to be.
  4. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Tranes are really commercial grade units. So you won't find much support unless you have a Trane guy around. And that Trane guy is generally not interested in residential work.

    The only ones I've seen in houses is because the homeowner "knew a guy". But then had us do the work?

    edit: I have two trane units kicking around from a bankrupt commercial client and I can't even source a price on them.
  5. KidMelody

    KidMelody New Member

    The newer trane systems are rebranded waterfurnaces. I just installed their TVGX which is the waterfurnace series 7. I know someone that works at waterfurnace in Indiana.

    A trane system from 2001 I have no clue though. A trane rep told me they got out of geothermal for residential and focused on commercial geothermal for a period of time.
  6. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    The delta T on the coil should not change much wether one loop pump is running or two. The capacity is not changing much with different flow rates (wether you have 3 gpm with 2 pumps, or 2 gpm with pump), especially when the loop is around 55F. You probably picked more of a steady state air temp after running it for a while.

    Measure the pressure drop on the loop side between going in and out of the unit. With that you can compute the flow rate. Then measure the delta t.
    Take the flow rate in GPM, multiply it with the delta T and multiply that with 485 (assuming you have antifreeze in the loop in Maryland). That will give you the heat extraction. Check the specific heat extraction in the table. That way you know that your refrigerant circuit is OK. That is pretty much all you can do.

    If I am not mistaken, Trane GSHPs are made by Waterfurnace (at least recently), so the parts should be similar if not the same.
  7. officeguy

    officeguy New Member

    It is a push-pull setup with one one pump on the line going to the wells and one on the return. If one of the pumps is off, the GPM is decreased.

    There is a 2T split unit for the upstairs bedrooms but it is hooked to a different well.

    I am a noob to the geothermal system world. How do I determine GPM. I assume by measuring pressure between the heat-pump 'in' and 'out' ports. Is the table to calculate GPM from pressure drop specific to the unit or is there a standard table you can use for all pumps ?

    I dont know who made the actual box, Trane or Waterfurnace. Any way to check based on the innards ?
  8. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Older heat pump techs do not need smart phones to fix stuff.

    We learned to take readings with reliable instruments and act in the best interest of our customers.

    GPM in and out and the table should give you GPM total heating or cooling.

    Do you want affirmation or real numbers?
  9. geoxne

    geoxne Active Member Forum Leader

  10. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    here is also a flow rate calculator. You need the pressure drop at a given flow, and it will calculate the flow at your measured pressure drop.
    It is specific for each unit, so the tables are in the installation manual.
  11. officeguy

    officeguy New Member

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