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Non-pressurized flow center?

Chuck_17Chuck_17 Posts: 111Member
Ground source heat pump system with closed loop wells.
I'm looking at a non-pressurized flow center (Phoenix Energy Supply). Installed and has been in operation.
I'm not quite sure what to make of it.
I don't think there is an expansion tank on the system so let's say the system is not pressurized.
How would you know there is enough water in the system?
What is the advantage?

Comments

  • hot_rodhot_rod Posts: 11,461Member
    The tank or canister becomes the fill point and also the expansion space.

    A couple things to remember with open, unpressurized loops. Oxygen will get in and O2 supports corrosion. Most pump manufacturers suggest against cast iron body circs on open systems.

    Some manufacturers have tried an E coating on the volutes for this issue, limited success from what I see and hear in the field.

    With an open system you have little NPSH on and circ connected into the systems. In some cases as many as 4 pumps are in series so the potential for cavitation is increased especially if high head models are used.

    If you use any inhibited fluids like glycol of alcohol based the inhibitors will need to be checked and boosted as the constant O2 ingress will deplete the protection of the inhibitors.

    Advantages? Easy to monitor and fill the system, some air elimination is possible in the tank.

    Personally I feel any hydronic, solar, geo, wood fired device should be under pressure for all the above reasons.

    More and more we see ECM GEO circulators being used in closed loop systems with modulating or staged heat pumps, an ideal match for adjusting to changing load conditions.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Chuck_17Chuck_17 Posts: 111Member
    I'm still a little foggy on how it is not pressurized. All the heat pumps are above the flow center. How to fill enough but not pressurize?
  • A.J.A.J. Posts: 257Member
    Good point Hot Rod, we started out doing pressurized loops but the last couple of years we started doing nonpressurized because of the ease. Maybe we should go back if the geo market ever bounces back.
    Andy
  • ethicalpaulethicalpaul Posts: 714Member
    For a DIYer the non pressurized flow center is really super easy to install. No pressure rig to worry about, just pour the water and glycol in, run it for awhile with the filter tube installed to catch any dirt and to let the bubbles come out and you are golden.
    1 pipe Utica 112 in Cedar Grove, NJ, 1913 coal > oil > NG
  • leonzleonz Posts: 328Member
    edited October 2018
    Chuck said:

    Ground source heat pump system with closed loop wells.
    I'm looking at a non-pressurized flow center (Phoenix Energy Supply). Installed and has been in operation.
    I'm not quite sure what to make of it.
    I don't think there is an expansion tank on the system so let's say the system is not pressurized.
    How would you know there is enough water in the system?
    What is the advantage?

    =====================================================
    ===============================================================================================================================================================

    Is there a problem with the heating/cooling system? If the system has a leak the circulating pump would fail.


    The problem with closed loop systems is that it is only as good as the last butt electowelded fusing point which is the U in the bottom of the hole.
    With a surface installation its a case of how deep they set the tubing , how far apart the loops are, how well the pipe is bedded with sand to protect it in the trench enough pipe for a continuous loop with no butt welded joints .

    The manufacturers of the U connector joints that are fused to the two loop pipes are lowered in to the drilled well use a heavy weight to hold it in place down in the bottom of the well to keep it from becoming buoyant and pushing up when the well is plugged with that thermally enhanced clay grout crap.

    When the geothermal business started using the butt fused U joints that were sealed in the "thermally enhanced clay grout" they had many many bad U connections that failed and the well fields were either abandoned or re drilled and the mess was still in the ground AND you never new which loop drained the system UNLESS you pulled every loop out if you were able to.

    I still choke when I see or hear people brag about thermally enhanced grout as all it does is doing is insulating the piping reducing the ability of the system to transfer heat and conduct cold temperatures back to the tubing and your better off pumping mason sand in the hole with the tremie pipe when you lower the loop if you insist on doing it that way.

    Me I would rather see an open loop system which is preferable in any case or a semi open loop system in drilled rock or a sealed and cemented steel threaded pipe joint casing with a deep well depth for cooling and heating using one deep well or a shallow twin well system where one well is used for heating and the opposing well is used for cooling at a longer distance away from the home or business as the earths ability to shed the heat from the water would be reduced if the wells are too close to each other.

    I still get a bit twisted and cringe when I see these systems installed using HDD rigs that drill a radial spoke pattern from a single point using "thermally enhanced grout" (UGH) and soft copper pipe in the loops and its only a matter of time before the copper goes bad in the ground.
    They use a small surface placed vault to make all the header pipe connections for the radial drilled loops to send one pipe into the home for the cold water/glycol mix and a second header pipe connection from the home in the vault to return the hot water/glycol mix to be cooled.

    =======================================================
    For every one hundred foot of well depth you would have approximately 1 ton of cooling power and the related heating BTU value amount.
    In a semi open loop you drill into bed rock and if you get water you can drill further and increase the wells depth as long you have a continuous depth of bed rock and no heavy black clay that would act like bed rock and eventually collapse up to the bottom of the casing.
    (been there done that with my own potable water well)

    The semi open loop method using steel casing cemented into the good bedrock for the well and would allow the user to have a deep well depth and the static water level would be where it rises under its own pressure in the well and stops.

    Most of these systems use a single deep well submersible pump
    with a 2 pipe jet sanitary seal to return the hot water back in to the well.
    The deep well lets the user simply pump from the bottom of the well to get all the cold water the system needs and the warm water is just drained back into the top of the water column using a 2 pipe jet pump sanitary seal and the warm water would just fall back down to the bottom of the well to become cooler again.

    Using a deep well submersible pump lends it self to lightning strikes and failure(been there done that many times at my house as the steel well casing loves acting like a lightning rod and the water in the well; well you know that water loves to conduct electricity and short out well pumps.
    (been there done that with close to 15 pumps since this well was drilled in 1979).

  • ethicalpaulethicalpaul Posts: 714Member
    > The manufacturers of the U connector joints that are fused to the two loop pipes are lowered in to the drilled well use a heavy weight to hold it in place down in the bottom of the well to keep it from becoming buoyant and pushing up when the well is plugged with that thermally enhanced clay grout crap.

    This wasn't my experience. The drilling contractor drilled 550' down. Then he lowered the pipes basically by hand off of a spool until it got to the water line where as you say it became buoyant.

    At that point, they just filled the pipes with water to allow them to be pushed all the way to the bottom. Then they pumped in the grout. The grout was measured by my engineer on site for heat conductance value to ensure they were mixing it properly.

    There was no weight on the bottom of the pipe and I saw the weld, as well as the intermediate welds they did on site, and if they fail before I do (in about 40 years hopefully), I'd be pretty shocked.
    1 pipe Utica 112 in Cedar Grove, NJ, 1913 coal > oil > NG
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