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Glycol header pressures- help please

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  • Glycol header pressures- help please

    Hello. I installed my glycol unit which I purchased used. The previous owner told me that they had 1.5 inch headers with no pressure reducers etc and the unit ran at 20 psi.

    Fast forward to today. My headers are 2 inch copper. I thought this would reduce pressure plenty I have taken all the steps recommended by pro refrigeration and I am confident in that.
    Click image for larger version

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    Here is a picture of the pump

    My glycol header is near 60 ft long. My pressure is running at 45 psi. I have not put this to my tanks and will not until I can reduce it.

    Any ideas or suggestions? New pump, vfd? I'd appreciate any help.

    Thanks

  • #2
    VFD connected to pressure sensor.

    Comment


    • #3
      Ok. Thanks.

      Now here is another thought. I have my pressure relief valve set to not relieve at all. I know I would normally set it to just above 15. Is the prv supposed to be open any time a tank is not taking glycol? Or should header pressure be at 15 with all tanks not taking glycol and the pressure bypass closed?

      Thanks

      Comment


      • #4
        We have our PRV set to relieve (from the supply into the return) slightly below the setpoint on the supply side (15) so that there is always a little bit of flow to prevent the pump from being deadheaded.

        Comment


        • #5
          While not a perfect solution to your pressure issue, we installed a valve at the end of our line which connects supply and return. That way, we can partially open it to prevent the pump from ever deadheading and can use it to reduce pressure (by opening it more) if few tanks are calling for coolant. Also, I've found that if I'm transitioning from fermentation temp to conditioning temp on a lot of tanks I can open the valve fully when I set the chiller to reduce coolant temp and we get to working temp much faster. Then I return it to nearly close which maximizes pressure in the tanks calling for cold.

          Seems to speed things up a bit. But, this is not a giant tank farm by any means, 1 15, 3 17 and 1 7.
          Chief Fermentation Officer
          Oregon Mead & Cider Co.

          Comment


          • #6
            Bypass Regulator

            Every pipe system build out is unique in the way they run.
            All you need is a 3/4" unit for your purposes and they work reliably and are way cheaper and quicker than VFDs and other things.
            I have 3 Chillers on property. The package units all have these on board and my built up system has one that works in the exact same way. Put a gauge on your discharge line and set it right where you want. Pipe the outlet back to your glycol well.
            This is an example of what they look like.
            Shop Isopure Water For The #1 Premium Home Water Filtration Systems, Water Softening Systems, Replacement Filters, & More At The Best Prices For Sale Online.


            There should be a former thread on the subject where I listed the exact part# used. They are made by Watts.
            Never had one fail on glycol.
            Last edited by Starcat; 02-14-2016, 02:53 PM.
            Warren Turner
            Industrial Engineering Technician
            HVACR-Electrical Systems Specialist
            Moab Brewery
            The Thought Police are Attempting to Suppress Free Speech and Sugar coat everything. This is both Cowardice and Treason given to their own kind.

            Comment


            • #7
              Well. Now pressure is good but my compressor isn't running. It's real cold outside. It was running Saturday.

              Comment


              • #8
                Originally posted by Reinstone View Post
                Well. Now pressure is good but my compressor isn't running. It's real cold outside. It was running Saturday.
                You probably have a low pressure freeze. Check the concentration of your glycol. I'm in the northeast and we have had some negative temps. Had to go to the roof yesterday to ad more glycol and reset the low pressure trip. http://www.prochiller.com/reGlycolChart.html

                Comment


                • #9
                  Low Ambient Setup and Tuning

                  Originally posted by soia1138 View Post
                  You probably have a low pressure freeze. Check the concentration of your glycol. I'm in the northeast and we have had some negative temps. Had to go to the roof yesterday to ad more glycol and reset the low pressure trip. http://www.prochiller.com/reGlycolChart.html
                  The Glycol BRIX is critical as noted above, but there are an array of other very fine points that are almost always missed unless the system is dialed in by an HVACR Pro who understands Low ambient tuning which is as art and will vary depending on the location.
                  The BRIX can neither be too low nor too high. Both conditions will cause low ambient control problems but for different reasons. IN our location which can get moderately sustained cold but not severely cold for extended periods, 29 works. You need to remember that glycol viscosity is heavy and pumping efficiency is reduced with temperature drop and overconcentration This is a hint for over brix trips.

                  Low Ambient control on HVAC machines is accomplished in a number of ways which are getting more electronic in this age, but time tested systems operate as thus:
                  Flooding controls which require the critical receiver charge to be absolutely correct and not short.
                  Fan cycling controls, and depending on the number of fans on the condenser bank thermostatic controls on typically one fan in the bank...ALL which must be expertly tuned for the location in order for the system to be optimized.
                  Your Pumpdown control or LPCO also has to be correctly set ot it can and will cause problems.
                  Even a brand new unit is not unfortunately plug and play. An expert install and startup is everything to the future success of the system.
                  Warren Turner
                  Industrial Engineering Technician
                  HVACR-Electrical Systems Specialist
                  Moab Brewery
                  The Thought Police are Attempting to Suppress Free Speech and Sugar coat everything. This is both Cowardice and Treason given to their own kind.

                  Comment


                  • #10
                    Originally posted by Starcat View Post
                    The Glycol BRIX is critical as noted above, but there are an array of other very fine points that are almost always missed unless the system is dialed in by an HVACR Pro who understands Low ambient tuning which is as art and will vary depending on the location.
                    The BRIX can neither be too low nor too high. Both conditions will cause low ambient control problems but for different reasons. IN our location which can get moderately sustained cold but not severely cold for extended periods, 29 works. You need to remember that glycol viscosity is heavy and pumping efficiency is reduced with temperature drop and overconcentration This is a hint for over brix trips.

                    Low Ambient control on HVAC machines is accomplished in a number of ways which are getting more electronic in this age, but time tested systems operate as thus:
                    Flooding controls which require the critical receiver charge to be absolutely correct and not short.
                    Fan cycling controls, and depending on the number of fans on the condenser bank thermostatic controls on typically one fan in the bank...ALL which must be expertly tuned for the location in order for the system to be optimized.
                    Your Pumpdown control or LPCO also has to be correctly set ot it can and will cause problems.
                    Even a brand new unit is not unfortunately plug and play. An expert install and startup is everything to the future success of the system.
                    Great points. I actually have two sets of parameters that I've been using given the wide swing of ambient temps we experience here. One for spring into summer, then in fall I switch to winter.

                    Comment


                    • #11
                      BBQ.


                      Sent from my iPhone using Tapatalk

                      Comment


                      • #12
                        Originally posted by dmartin View Post
                        BBQ.


                        Sent from my iPhone using Tapatalk
                        Sorry. Seems like my two year old has been posting in various threads.


                        Sent from my iPhone using Tapatalk

                        Comment


                        • #13
                          Understanding the chiller system you purchased doesn't have a built in pressure bypass valve, but you have a PRV installed on the glycol loop that is set to not open- at any pressure.

                          If your tank jackets are not designed to handle more than 15 PSI pressure, I'd do a test and adjust the pressure relief valve to open and maintain 15 PSI Supply when only a single tank is calling for cooling. As more tanks open, the valve should modulate to bypass less and maintain this Header pressure. It isn't an issue if the header pressure exceeds 15 PSI when all of the inlet valves are closed because you won't be exposing the tanks to this pressure.

                          Also keep in mind that you don't want to "dead head" this pump when all of the tanks are OFF and don't require cooling, you will want some flow to be bypassed to prevent total loss of flow and risk damaging or losing the pump seal (and your glycol solution) from the heat that will be generated by the pumps rotating impeller without water flow.

                          Variable Frequency Drives are great for helping with this too- controlling via a pressure transducer and maintaining a setpoint pressure as tanks open and close. But this not a single solution as transducer sensors do fail and you will still want a Pressure bypass valve somewhere in the system to protect in the event the drive sensor fails and the pump could deliver >15 PSI pressure.

                          Hope this is helpful, good luck as you get your system dialed in!

                          Sincerely,

                          Jim VanderGiessen Jr
                          Pro Refrigeration Inc.
                          Last edited by jimvgjr; 02-16-2016, 04:56 PM.

                          Comment


                          • #14
                            Thanks

                            It's been a long weekend but with help from everyone here I worked through these issues

                            1. Compressor -low refrigerant pressure switch needed adjusted to meet the Illinois winter.
                            2. Glycol- solenoids not opening, prv not open at correct pressure


                            Running great now at 15 psi, with no load
                            12-13 psi with 4 tank load


                            Thank you very much.
                            Attached Files

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                            • #15
                              Oh yeah. Wrong pic. You get the idea

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