what are appropriate entering water pressures?

Discussion in 'Open Loop' started by kelargo, Jul 16, 2011.

  1. kelargo

    kelargo New Member

    what are appropriate entering water pressures?

    I am looking at my manufacturer's product documentation. The GPM volume and Entering Water Temperature ranges are listed. The documentation also shows the pressure drop through the system. But I'm not seeing specific info on recommended entering water pressure.

    Is there any rule of thumb as to valid pressure ranges? Is 90 PSI too high?
    Is 30 PSI too low? as long as the recommended GPM is kept?

    Documentation says flow ranges between 7 and 13 GPM and pressure drop of 3 to 7 PSI.

    Wondering if an irrigation pressure regulator would be ok ?

    something like this:

    PMR35MF4F4F - 1"" 35 Pressure Regulator 2-20 GPM, by Senninger

    thank you
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader


    Pressure is irrelevant. Pressure drop is to determine flowrates.
  3. kelargo

    kelargo New Member

    wouldn't too high a pressure cause excessive wear in the coils? 90 PSI is not too high?

    pipe size is also a major factor in flow rates, to deliver the volume.
  4. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader


    Yes, that goes without saying, but that is a different question. You want to minimize head loss in your plumbing setup to reduce your pump size. Once again, the heat pump doesn't care about pressure as long as it has flow (and no air).

    Usually when we go down this path, you are looking at tying geo in to your domestic system? Most geo spec's are going to assume you have a dedicated source.

    Any pressure reducer/ flow regulator is going to introduce inefficiencies in to the system. Pump is likely oversized for example. We are all about efficiency, but if you are working with what you already have - reduce away. Put it somewhere in the " middle" :) 10-30 psi range is fine.
  5. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Aggree with above.
    If you are running the geo from a household supply you used energy to achieve the pressure. The lower the out put pressure the lower the amount of energy needed to move a given volume of water. High pressures 40-90 psi create noise in the coil that can be a form of noise pollution in the home. A pressure reducing valve like the one you mentioned will help to avoid the "roar" of water through the coil.
  6. kelargo

    kelargo New Member

    energy loss?


    So, I guess the energy lost from the water going through the regulator results in an increase in water temperature, as well as being absorbed into the regulator body and tubing?

    Is it a very significant amount? In some way, this might not be bad, in that it would increase entering water temperature some small amount? and better than having the energy lost as sound being generated in the coils! :D

    any idea in how much energy gets lost in other things in the water path? such as a Blue-White flow meter? or a Sediment filter? I can always put in pressure sensors along the pathway to see the results.. just wondering ...
  7. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Head loss

    Your energy loss is in the oversized pump required to pump through the system. Each of those fittings adds a head loss to the system. That a larger and larger pump would be required to deal with.

    Basically, unless you are re-sizing a pump and not already working with your oversized domestic pump, you have already lost all the energy anyway ( without getting too specific).

    Edit - of course you may have a vfd, or multi speed pump, or parallel plumbing, but I'm assuming not or you likely would have mentioned it.

    The real answer is you are saving on capital costs by using what you already have but you will be paying more in operating costs.
    Last edited: Jul 16, 2011

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