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Messages - denogail

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Thank you Richard...I do understand the idea of isolation...between the two units.  I have been monitoring the first modification...the shorting of the sense tube touching the insulator on the evaporator...What I did, was to make a"J" on the end, like the book calls for, but 1/2 the size.  Meaning, there is about 2 inches of sense tube involved instead of the 5 inches.  This has lowered the internal temp of the top evaporator by 3 degrees.  Yes, that is an improvement.  Keep in mind that I never really had a problem with keeping stuff frozen for months on end.  But, I just wanted to get the box a little colder.

I understand, also, about the speed resistor, and the #2 compressor running at 2000.  In the beginning, when I install these 3 different units, 2 in the freezer, and 1 for the refrig..seperate box...I connected blue LED's to each AUX fan terminal on the controller.  These LED's are on the dash of the boat, with labels, so I know when each unit turns on and off.  I have timed the on/off duty cycle, to make sure that none go over 50% ON I have heard/read? the units are not designed for that.  Anyways, the refrig runs at about 25% duty cycle, and the top evaporator in the freezer runs at about 20%, when the box is down to temp, and I have not put anything new in to be frozen.  The bottom evaporator in the freezer, well it does turn on, sometimes, but the ON/OFF duty cycle of that evaporator is around 5%.

So, as soon as I get time to crawl outboard, where the compressors are located, and hang upside down, I will install the relay, that you have mentioned.

Thanks again..Denns

Again..Richard, thank you for the information.  I do have the necessary relay and switch.  I understand what you are saying.  I will get to the back of the units and make the necessary changes. 


Richard..good morning...

first question...yes...two complete independent AB units wired separately to the main buss with individual circuit breakers.
Yes...both ab units have the stainless steel box with the two small fuses, and the LED.
Yes....two separate TSTATS

After 24 hours of run time with the reduced sense tube connected to the top evaporator, I have lowered the internal evaporator temp by about 3 degrees, which is OK.  And, actually, I am happy with this.  This system has been installed for about 7 years now, without any problems, and I do not have any problems now.  Just thought I could get the freezer a little colder.  This is a 2.3 cuft area, and is full of meat.  We travel to the Bahamas for 6 months, and everything stays frozen.  Until ready to consume. 

Richard..I know, if it ain't broke, don't fix it and if it ain't broke...don't use it!  I just thought it would be nice if both units turn on and off at the same time.  I installed 2 units in the same box for redundance incase one or the other should fail, while I am out in the middle of nowhere, with a box full of meat, fish, and lobsters.

I built the box, with good quality urethane foam.  5 inches on the bottom, 4 inches on all sides, and 5 inches on the top.  Top loading, with an internal fiberglass vapor barrier.

One thing that I did notice was...the upper evaporator, with the reduced sense tube has taken control of the box.  Meaning, that it gets the freezer colder and the lower evaporator never gets a chance to cycle on, as coldness to speak.

I was just thinking, if I could turn on both units, when the top evaporator turns on, the bottom evaporator would get used more, and the whole freezer would get colder.

Using a relay...would that go into the TSTAT wire?  One TSTAT turns on the other TSTAT..

Richard..thank you for your expert help and recommendations.

OK, Richard...I removed the sense tube, and put a smaller "U"..about 1/2 the normal recommended size and reclamped it.  This did in fact lower the temp a few degrees.  I will wait for 24 hours, to see what the final temp settles into, as the 2.3 CUFT freezer is loaded to the top with meat.

Now, my next question, to the expert is:  Since I have 2 evaporators (2 complete systems) running in the box, the bottom evaporator probably will never turn on.  In case you are confused, I installed two evaporators, when I built this freezer, thinking that one would not handle the load.  I drilled out the pop rivits on the top evaporator, to remove the bottom plate.  So, picture one evaporator sitting on top of the other. Well, that really wasn't a question...but here is the question.  Is there some way that I can tie one TSTAT to run both units.  I am thinking it would be nice to have both compressors/evaporators turn on and off at the same time.  Other wise, the bottom evaporator, as mentioned, probably will never turn on, unless there is a failure in the top unit.

I hope I have explained myself..what do you think...DenO

wow...Richard, I did not think of reducing the amount of sensing tubing touching the evaporator...that will be easier and cheaper for me to do.  I do have the sense tube formed in the "U" shape, as recommended in the install lit. thank you for the info.  I will do it tomorrow, and let you know.


I know this probably has been asked by other, so forgive me.  I see over on the web site that they have for sale a "freezer" thermostat that will bet the Adler Barbour colder, for a freezer configuration.  Is this just a change in the resistor value in the TSTAT itself, or is it a different sensing tube.  I would like to get it colder in there, and extra run time is OK.  Is it true that if I just change the resistor value to make the compressor run faster, will only make the box get cold...faster...but not colder?

If I do need a different TSTAT..what do you recommend?


Boat Refrigeration / Re: How do I lower the temperature in my freezer....
« on: November 10, 2013, 07:09:57 am »
Thank you Richard for the info on the small + and the F wires running a small relay to provide a  closure to the yellow and green wires on the other tstat for an ON signal.

I will do this...however..just one last question and I think I know the answer to this...but when in doubt, one should ask the expert...Should I use the top evaporator/tstat as the master or the slave or the bottom evaporator/tstat.  As I mentioned in an earlier post, the top evaporator/tstat cycles much more then the bottom, and the coldness that that produces sinks down to hold the bottom off.

Thank you again for your time...


Boat Refrigeration / Re: How do I lower the temperature in my freezer....
« on: November 09, 2013, 06:50:51 am »
Good morning Richard...anyways...morning is here.  In looking at the wiring diagram for the standard tstat, I see that only two wires of the 4 are used for the standard tstat.  This means that the tstat itself is a simple switch, depending of course where the knob is set to turn on and off.  In tracing the yellow and green wire back to the compressor control module, it appears to me that the tstat switch when it gives the command to turn on the compressor,  is simply suppling a ground signal to the brown wire as it goes into the compressor control module plus a resistive value for speed. it possible to control both compressors/evaporators with a single tstat.  The reason you I have noticed over the years that this system has been running is that: When the bottom evaporator does turn on (and doesn't happen to often...because the top evaporator works more dropping the "coldness" down to the bottom of the box, holding the bottom evaporator off) the temperature in box drops down to around 0 degrees F.

So, do you think it is possile to take either tstat, disconnect the wires from one and tie the yellow and greens wires together, respectively to control both evaporators/compressors with one tstat?

Thank you again...DenO

Boat Refrigeration / Re: How do I lower the temperature in my freezer....
« on: November 06, 2013, 05:48:24 pm »
Once again, Richard, thank you for your input....always ask the pros which you are!

I will reduce the sensing tube contact down to 2 inches or so.  One final question, it true that the compressor cannot or should not run more then a 50% duty due to the possibility of premature failure?

Thanks again...very much...DenO

Boat Refrigeration / Re: How do I lower the temperature in my freezer....
« on: November 06, 2013, 06:58:49 am »
Thank you Richard for your reply.  As far as to evaporators in one box..let me try to explain again.  These are the large evaporators by Adler Barbour (now Dometic).  The first vertical evaporator mounted on the back wall down at the bottom of the box.  The second evaporator, I removed the thin metal bottome plate of the second vertical evaporator by drilling out the pop rivits and then mounted this evaporator on the back wall on top of the first.

Now you mentioned a freezer there such a think?  Where can I get 2...?

Is it possible to put an extra piece of insulator between the sensing bulb and the evaporator on the side?  Would this trick the existing thermostat to think that the evaporator is not getting cold enough to turn off, and run longer?

Thank you  DenO

Boat Refrigeration / How do I lower the temperature in my freezer....
« on: November 04, 2013, 07:01:46 am » is what I have.  I built my own box with 5 inches of good R value foam all around.  The freezer (dedicated) is about 3.5 cubic feet.  I have 2 Adler Barbours stacked one on top of the other (large evaporators), each with it's own thermostat control and compressor.  I remove the bottom plate of the top vertical evaporator so I could load frozen stuff straight through to the bottom evaporator.  I have had this system working now for 7 years, and stuff does stay frozen, but the temperature runs at about 22 degrees F.  Nothing goes bad at this temperature, and we are out in the Bahamas for 6 months.

The question is: How can I make the temperature lower.  Would changing the resistor value in the thermostat, thus making the compressor run faster lower the temp?  But, I seem to have read somewhere, that the Danfross compressor should not run more then a 50% duty cycle...true or false?  Right now, I believe my duty cycle is around 25%, so I think I could afford to run the compressor at a  higher speed.  What do you think, and what resistance value should I use in the thermostat?

BTW...the top evaporator runs much more then the bottom, due to the coldness sinking, holding the bottom evaporator off.  But the bottom does turn on once in a while.  When this does happen, the temperature in the box drops to around 0 degrees F and slowly warms up to 20 or so degrees.

Again, all works well, and the fish and lobster stay frozen, but I would like to get it alittle colder.  Thank you for your reading time.


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