Flow switch lockouts--over 100 in 6 weeks

Discussion in 'Maintenance and Troubleshooting' started by Lockedout, Feb 8, 2012.

  1. Bergy

    Bergy Member Industry Professional Forum Leader


    This is a GWT070 6 ton unpressurized closed loop system and would require 18 GPM flowing through both the source and load side.

  2. Bergy

    Bergy Member Industry Professional Forum Leader


    You said "As we watched it yesterday---with the cover on---the compressor would stop suddenly--well below the temp setpoint and with a pressure of 400-425 psi---and then the flow switch would lock out after 30 seconds. Is it sensing that the flow has stopped midcycle and is acting correctly? Is it possible that excessive heat is building up inside the cabinet and forcing some kind of electric short?"

    This is a very intresting statment. The compressor shuts down THEN the flow switch locks out may cause me to lose some sleep thinking about that... :cool:

    Also, what 400-425 PSI are you speaking of? What is measuring that PSI?

  3. geoxne

    geoxne Active Member Forum Leader

    Doc said-
    Don't blame Bergy, that was me. I apologize, I was reading the 1st stage performance chart.

    I do not understand why gauges have been put on the refrigerant circuit, if the lockout is for water flow. The GWT070 has 2 mechanical flow switches (Load and Source) wired in series to the control board. If there is a flow switch lockout, it should be determined which side is causing the lockout before any other work is done. We still have not seen any load side temperatures to see if they are out of range.

    The lockout lamp on the outside does not tell you what the lockout is caused by, the LED lights on the control board do. Is it possible the unit is locking out for something else?
  4. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    400-425 psig for R410a corresponds to a saturation temperature around 120*F. That's high.

    The request for load side temperatures is in order. This may be a case of low airflow or a dirty aircoil - have either been checked?

    Has compressor current been measured and compared with RLA?

    I wonder if the low flow alarm is coming in after the loop fluid stops flowing owing to pump shutdown following a trip.

    Given that systems, particularly open loop, can operate on as little as 1.5 GPM per ton, I would not expect that being a bit below 3 GPM per ton is responsible for a low flow trip.
  5. jrh

    jrh Member

    How does your installer know there is a pressure drop of 4(PSI?) on the Load side if there are no ports to get a reading from?

    I would agree that 13 gpm on the source side should not cause the flow switch to open. Has the Flow meter been on the flow center showing 13 gpm as it locked out? Or was flow meter on it an hour earlier?

    I am also troubled that refrigerant gauges have been on the unit before flow has been verified on the load side. This shows a lack of fundamental knowledge of water to water heat pumps.

    My guess if that the pumps on the load side are are not separated Hydraulically. This is very important.

    I took Enertechs factory training.They were very clear that they want the Load side flow to match the source side flow.
  6. jrh

    jrh Member

    How many pumps are on the load side?
    Are those pumps or zone valves that are wrapped up in the insulation?
  7. ACES-Energy

    ACES-Energy Member Industry Professional Forum Leader

    Doc is in Buffalo and I am in Rochester if you need any support on site.

    If it is who I think it is, I have been to a few of those jobs to correct. I believe those are pumps, not zone valves under the insulation.

    Although from what I have read, your loop field should operate fine, but over time you should give some though to changing out for Methanol.
  8. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    My earlier response didn't account for water rather than air on the load side, but the same reasoning still applies.
  9. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader


    while Enertech publishes its performance data with a delta t of 6.9F corresponding to 18 gpm flow, do you have any reference that the GWT070 (which by the way is discontinued) actually requires 18 GPM flow on the load side? For example Climatemaster gives you a range of 6-18F for a delta T on the load side, which corresponds down to 1.3 gpm/ton.
    Flow switches kick in at 1.1 gpm/tom on the Enertech equipment, if I am not mistaken.
  10. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader


    AJ is right. I have a deja vue here as well. Lets cut to the chase: Who is the installer?
  11. Bergy

    Bergy Member Industry Professional Forum Leader


    Enertech's minimum closed loop flow rates would be 2.25 GPM/ton. However, Optimum flow rate is 3 GPM/ton. In Enertech's training they want source side and load side flow rates equal.

  12. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    This does not make any sense. So if I have an open loop with 1.5 GPM, now it is OK to have 1.5 GPM/ton on the load side, especially with the heatpump putting out more heat because of the higher EWT? Don't get me wrong, naturally, I am a big flow fan, since it increases the efficiency, but would I add a second pump to increase the flow to be right at the specs? No.
  13. Lockedout

    Lockedout New Member

    A solution finally!

    Since I last posted 2 weeks ago---

    The system has been running without locking out with the cover OFF. The contractor contacted Enertech 2/13 and they determined it was a faulty Logic Board. The new board was installed Thursday (3 days ago) and the cover was placed back on. The system has NOT locked out since. The temperatures have been in the 20s at night--so I'm hopeful he has finally solved the issue. Thanks to your comments and the independent contractor review, we have a rather lengthy list of items that need to be corrected, but for now, I consider the flow switch lockouts resolved. I thank you all for your input and comments. :)
  14. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    No Problem

    Our pleasure.

  15. Bergy

    Bergy Member Industry Professional Forum Leader

    I'm sorry for not answering your question earlier.... Because the Load Side is a closed loop, water flow should be set to 3 GPM/ton. This is per Enertech's Tech service department.


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