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Grunert Holding Plate Trouble
May 4, 2011
8:20 am
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Steve Pooler
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rka699 said:

To answer your post furthur, I have never done any checking of temperatures in my boxes.  I set the termostat(on both freezer and frig) at a very low setting, about 2-3 on the stat and let the unit cycle.  While at the dock, I leave the unit on all the time and the compressor cycles on and off from time to time, but I am not sure if it is the freezer calling for cooling or the frig.  In retrospect, I have not done a good job of documenting what is going on with my system.

Thanks again for your time, comments and advise,

Raymond Ames

I can't really answer those questions for you other than to say…Weigh the differences and decide what is better for your usage.

  • Do you really need Hold Over periods since you have an inverter & will that inverter/battery package power the system efficiently…Meaning will it add substantial run time (and fuel usage) to the engine recharging batteries on long passages ??…Remember that standard plates will likely cool the box down much quicker after opening, but will cycle the compressor on box temp…Not plate temp.
  • Would extra space in the box/s be beneficial ??…Or not really a concern ??

Don't feel bad about not documenting what was going on in your system…Most people don't understand hold over plates and (thus my article) use them like any standard system as they would at home…

As I said in the article though…Hold over plates were not designed or intended to operate that way, and are not as good at it as standard plates would be...Remember that the compressors duty in the holding plate application is meant to keep the plate frozen (solid) and that the box temp when that plate is frozen depends on all the box factors (insulation, gaskets, plate size etc.) or BTU of heat leaking in...This is Hold Over temp, and that's what it is Intended/Designed to do.

 

Steve~

 

May 4, 2011
7:37 am
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rka699 said:

Wow!  After reading your post, I take it that you are not a big proponant of holding plates...It's not that I don't like hold over systems...They are good for the purpose intended...But I wrote that article for folks to understand that they should not be expected to perform the same as what they may be used to at home, and that there are drawbacks that come with the technology...Understanding their operation/function is one of the biggest misunderstandings...With the expense that I will be going through, I'm not sure if I should change to a flat plate or stay with my current design.   In reviewing the data, my box was underdesigned to begin with for a 24 hour BTU loss, I am more like 12 hour loss.  For all of these years, I have not worried about power consumption as I have a wind generator, large house batteries with inverter,  and a genset, so even on long cruises, I just run the unit a couple of times a day to maintain temperatures....This is why I asked about your "Hold Over" temps...Meaning what temp did the box/s maintain for the longest period...With the system off...This should be when the plate/s were transitioning from solid to liquid...And defines "Hold Over" temp 

Yes the plates are expensive, $600.00+/- per plate.  In talking to Barry at Grunert, he stated that he had seen this situation only six times in his 20 years at Grunert, so maybe you have had more exposure to the situation than he....Yes Grunert builds a quality plate, but In my 20+ years servicing the west coast of Fl, I have seen many other brands...

Also as stated in your Grunert manual...They use a Brine solution (salty & safer than toxic glycol if leaking into box) then vacuum/evacuate the air from the plate to prevent corrosion inside...If this vacuum seal gets compromised (or someone opens the plug to check) the corrosion starts working on the tubing from that point on.  

Having said all of that, I am just not sure what to do at this point.  As usual, there is no simple answer.

I welcome your comments and advise.

 

Thanks again, Raymond Ames

May 3, 2011
10:48 am
rka699
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To answer your post furthur, I have never done any checking of temperatures in my boxes.  I set the termostat(on both freezer and frig) at a very low setting, about 2-3 on the stat and let the unit cycle.  While at the dock, I leave the unit on all the time and the compressor cycles on and off from time to time, but I am not sure if it is the freezer calling for cooling or the frig.  In retrospect, I have not done a good job of documenting what is going on with my system.

Thanks again for your time, comments and advise,

Raymond Ames

May 3, 2011
10:40 am
rka699
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Wow!  After reading your post, I take it that you are not a big proponant of holding plates.  With the expense that I will be going through, I'm not sure if I should change to a flat plate or stay with my current design.   In reviewing the data, my box was underdesigned to begin with for a 24 hour BTU loss, I am more like 12 hour loss.  For all of these years, I have not worried about power consumption as I have a wind generator, large house batteries with inverter,  and a genset, so even on long cruises, I just run the unit a couple of times a day to maintain temperatures. 

Yes the plates are expensive, $600.00+/- per plate.  In talking to Barry at Grunert, he stated that he had seen this situation only six times in his 20 years at Grunert, so maybe you have had more exposure to the situation than he. 

Having said all of that, I am just not sure what to do at this point.  As usual, there is no simple answer.

I welcome your comments and advise.

 

Thanks again, Raymond Ames

May 3, 2011
8:05 am
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Steve Pooler
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If you haven't already...I encourage you to go back thru your Passagemaker manual...It has a lot of good info, and here is a current copy in PDF if your's has gone by the wayside...

** you don't have permission to see this link **

 

Also: The below spec guide pages 29-30 are helpful in sizing plates for temps with a given box...

** you don't have permission to see this link **

 

Steve~

May 3, 2011
7:39 am
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Steve Pooler
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A few thoughts of caution/advise…

I know they are not cheap but…If you have had one plate fail and they are all the same age…The next may not be far behind.

What would really be a letdown is to go to the expense of replacing everything except 2 plates…Only to have the same thing happen to the new equipment from an old plate failing in the near future…

I mentioned it & of course it's your risk & decision  Confused

Next I might ask how the boxes performed with the plates configured as they were…What were your hold over temps ???

If considering plate replacement we may be able to improve on box hold over temps by changing plate temps…Grunert does offer three plate temps down to -18 -9 & 0 degrees.

I know you have lived with this hold over system for years but my post on hold over systems in this section will describe more of what I'm asking/talking about as to "Hold Over" temps…/forum/hold-overcold-plate-refrigeration/cold-platehold-over-refrigeration/

 

Steve~

May 2, 2011
7:32 pm
rka699
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Yes, I had the system installed in 1997.  I assume at that time that all componants where new.  I have since talked to Grunert and they concur with your findings that i will probably need to replace the condensing unit as well as expansions valves.  What fun!  I am not sure why the installer did what he did, i.e. a freezer plate in the frig and a frig plate in hte freezer but i am going to change the plates to have them in the right location.  I will have a 10 x 16 and a 10 x 20 zero degree plates in the freezer and a 10 x 16 26 degree plate in my frig.  My frig has 6 cubic feet of space and my freezer has 5.78 cubic feet.  Do you concur that this is the right thing to do? 

 

I appreciate your comments and time,

 

Raymond Ames

May 2, 2011
9:55 am
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Steve Pooler
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Hi Raymond…Thanks for posting~

What you are describing is not good news & yes I have seen the below many times…

It's highly likely that your refrigerant leak is inside the plate that has lost it's eutectic…Then what happens is, now the system is low on refrigerant, and due to that loss of refrigerant, the system compressor pulls the refrigerant circuit down into a vacuum when running…

This vacuum (suction) pulls the eutectic liquid into the refrigerant circuit thru the leak in the plate tubing…It then spreads throughout the complete system, and will (sometime soon) short out the compressor motor because it's now in the crankcase oil.

From your description of plates (odd temps for application) It's possible that there has been plate replacement in the past…

Have you owned this system since installation ?

Steve~

May 2, 2011
1:12 am
rka699
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I have a Grunert Passage Maker system installed in my boat.  I have a 10 x 20 0 degree and a 10 x 16 26 degree plate in my freezer section and a 10 x 20 0 degree plate in my refridgerator section.  Don't ask me why this is configured this way but it has been working wonderfully for the past 14 years.  I now have a problem with the 10 x 20 holding plate in my freezer, it has lost all of it's eutectic and at the same time I have lost all of my refrigerant.  I removed the plate for inspection and can see nothing on the outside that would be suspect of a leak.  I removed the "fill" plug on the side of the plate but in appears to have solid metal inside of the hole.  The refrigerant line appears to be clean on the inside.  I presserrized the refrigerant line with 20 psi but could not determine any leak.  Do you have any idea what could have went wrong and have you heard of this on other systems?

 

Thanks, Raymond