2 units, one loop field questions

Discussion in 'General Discussions' started by Jerome Scarpati, Jun 23, 2018.

  1. Jerome Scarpati

    Jerome Scarpati New Member

    Hello all,

    Quick question concerning conflicting info I am getting locally.
    Quick overview of the project:
    - new construction 4200 square ft home
    - one 4 ton unit in the basement
    - one 2.5 ton unit in the second floor
    - 8 individual loops of 800 ft all terminating in the basement

    Conflict:

    The original thought was to run all 8 loops into a single supply and return manifold, take that supply and return to a 4 pump QT-EA flow center. This would have two pumps for the second floor unit and 2 pumps for the basement unit. The nice part of this, in my mind, was that when one unit is working and the other isn’t, the working unit would have the benefit of the entire 6400 Ft of loop field. Also, when the kids all move away and we close down the second floor, my basement 4 ton unit would have the luxury of the entire loop field.

    The problem is that I have a local geo professional helping me out who claims that running both units off the same loop field is a recipe for disaster... he worries that one is going to steal from the other? He wants me to run 5 loops for the basement and 3 loops for the unstairs unit. I am just not sure if I follow the logic there and wanted to get some other opinions. I can’t be the only person to run two units off one loop field.

    Thoughts anyone? Is there a correct way to do this?
     
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    He's just afraid of the math. Combining the loopfields on a 2-circuit flowcentre makes perfect sense. Or a variable speed with valves.

    Commercial systems will run 10+ units off one loopfield.
     
    waterpirate likes this.
  3. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    The comments from your installer are silly, with the BS meter swinging out strongly.

    4 constant speed pumps in a flow center, especially 2 pumps for a 2.5 ton heat pump, strongly indicates an un-evolved installer. Who does not understand efficiency in a system.

    You'll be wasting a lot of pumping power. It raises a red flag.

    Key is a variable speed flowcenter, brochure attached.

    I have attached a piping diagram for 5 HPs on one loop field, concept is the same for 2 HPs, you don't need the dual pump loop field, in this example they are there only for redundancy.
     

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