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Isotherm ITC Digital Display Intelligent Temperature Control

Jun 3, 2012
569
Hunter 33 Bay Pointe, Quincy
I have the Isotherm Self Pumping Compact Refrigeration System. I later installed the Isotherm Intelligent ITC Digital Display Thermostat kit. My thermostat, however, does not work as it is described in the manual. According to the manual one of the features of this thermostat is that it will "overcool" when it senses that the batteries are being charged. Overcool is defined as lowering the normal setting by 5.4F (to 33F on mine) to store cold energy in the refrigerated items in the refrigerator. The compressor is permitted to go into high speed mode to accomplish this. When the Intelligent thermostat senses that the batteries are not being charged it automatically goes back to the normal temperature setting (39F on mine) and operates the compressor at a slower speed, except mine does not. Mine will always stay in overcool no matter what charge state my batteries are at. The threshold battery voltage that the manual says the system will switch out of overcool is 12.9 V. Mine never switches out of overcool and I have let it go down to 12.2 V. This is a great feature but it does not work. If it actually worked my batteries would keep my refrigerated items cold for longer with less battery consumption.

I contacted Isotherm customer support and received several different stories concerning this feature depending who I spoke to. One story was that it is not supposed to automatically go in and out of overcool, rather I must manually switch the system to ECO mode to exit overcool mode. Another story was that sure it may not work but all I have to do is operate it manually. And the last story, supposedly from the "Engineers in Italy," was that it may be a tolerance issue in the sensing of the battery voltage so why don't I just operate it manually and problem solved. Needless to say, I am very disappointed in Isotherm Customer Support. I requested a replacement circuit board but was refused. Beware fellow sailors!

Jackdaw, I think you have this system also. Does yours actually work? Anyone else have this intelligent thermostat system and does it actually works as advertised?
 
Jun 3, 2012
569
Hunter 33 Bay Pointe, Quincy
Apparently I am the only one who bought this system.
 
Sep 15, 2013
540
Catalina 270 270 Mystic Baltimore
I think I have one of those. First dumb question is do you have it set on the "arrow"?
 
Sep 15, 2013
540
Catalina 270 270 Mystic Baltimore
Nope. Do not have that one. Mine is the single dial. The "arrow" setting puts it in the auto made as you described.
 
Nov 7, 2011
2,509
Catalina 30 Mk II Barnegat, NJ
@RoyS
I'm interested in this as well as I'm planning on buying an Isotherm fridge.
According to the Isotherm literature (linked on the Defender website), you have the ITC controller. That appears to be a manual temperature control.
Isotherm's ISEC controller is listed as "automatic refrigeration control for high efficiency".

I wasn't sure what the differences between the two were so I just read the ITC manual.
Here is my take on it.
The Over Cooling function has to be turned on and off manually by the user.
The voltage table explains at what rpms the compressor can be run for various voltages. The high voltage is needed for the higher rpms for the Over Cooling mode to operate.
For Over Cooling to be automatic you need the ISEC controller.

Hope this helps.
 
Feb 5, 2004
3,933
Tartan 3800 Westport, MA
I am a bit annoyed at myself that I can't find the documentation I created for my fridge control design, but it won't be too hard to recreate.

What I'm talking about is that I researched this topic, thoroughly, and after sorting the features, and what my requirements are, designed a system. It does what the Isotherm Intelligent ITC Digital Display Thermostat does, as well as others out there. It turns out that for components of a marine fridge there's really only one game in town: Danfoss. They make compressor and evaporator units, and various controls, mostly for the refrigerated trucking market. These are repurposed by folks like Webasto, Dometic, et.al., in to marine fridges. The really intelligent part of the intelligent control is a controller Danfoss makes, the 101N0300, AOE - Adaptive Energy Optimization. You can find the manual by googling it. (I don't have the link handy.) The other part - "overcooling" when there's a charging source present - is fairly easily accomplished with an intelligent thermostat, or, in my case, two electronic temperature controllers, a voltage threshold detector, like a low voltage disconnect circuit ($5), and a couple of relays ($4). I use the Inkbird temperature controllers ITC-1000 ($15 each). One is set for "normal" use, on batteries, at 39º, the other takes over when V >= 12.7VDC (settable), and is set for 32º. Switches from normal to overcool and back, automatically.
 
Oct 26, 2010
781
Hunter 40.5 Beaufort, SC
Mine is the single rotary dial (non led/digital gauge) with an arrow for automatic overcool mode.

Seems to work fine. You do have to set the dip switches correctly, including any "offset" to get it to overcool to the 33 degree measured temperature. Its a little bit of a "trial and error" process.
 
Jun 3, 2012
569
Hunter 33 Bay Pointe, Quincy
Ward, you are both right and wrong about this controller. The manual is poorly written possibly as a result of having been poorly translated. On page 45 of the manual there is a chart comparing battery protection modes. I have selected "Medium Battery Protection" See chart below: With medium selected the "full speed overcooling threshold" is 12.9 V. When the voltage goes below 12.9 the system should switch out of overcooling but it does not. I have run the battery voltage down to 12.2 Volts and the compressor is still running at maximum speed and still attempting to overcool to 33F. You are right that it needs to be manually controlled but it is supposed to be automatic (intelligent).
 
Jun 3, 2012
569
Hunter 33 Bay Pointe, Quincy
Ward,
The manual does include a statement that to get out of ITC mode you must manually switch to EC mode. This is very confusing. Yes, to get out of ITC (Intelligent Temperature Control) you must switch to EC (Economy) mode. However, when in ITC mode the system should be fully automatic including the overcooling function. You should set it and forget it. If you want to not use the automatic overcool function you must manually switch out of it. Poorly written.
 
Jun 3, 2012
569
Hunter 33 Bay Pointe, Quincy
jviss, I salute you for building your own intelligent temperature controller. You are doing exactly what the Isotherm ITC thermostat claims it will do. Great if it only worked as described. Wish you worked for Isotherm because none of their engineers can figure this out.
 
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Nov 8, 2010
10,586
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
I have the Isotherm Self Pumping Compact Refrigeration System. I later installed the Isotherm Intelligent ITC Digital Display Thermostat kit. My thermostat, however, does not work as it is described in the manual. According to the manual one of the features of this thermostat is that it will "overcool" when it senses that the batteries are being charged. Overcool is defined as lowering the normal setting by 5.4F (to 33F on mine) to store cold energy in the refrigerated items in the refrigerator. The compressor is permitted to go into high speed mode to accomplish this. When the Intelligent thermostat senses that the batteries are not being charged it automatically goes back to the normal temperature setting (39F on mine) and operates the compressor at a slower speed, except mine does not. Mine will always stay in overcool no matter what charge state my batteries are at. The threshold battery voltage that the manual says the system will switch out of overcool is 12.9 V. Mine never switches out of overcool and I have let it go down to 12.2 V. This is a great feature but it does not work. If it actually worked my batteries would keep my refrigerated items cold for longer with less battery consumption.

I contacted Isotherm customer support and received several different stories concerning this feature depending who I spoke to. One story was that it is not supposed to automatically go in and out of overcool, rather I must manually switch the system to ECO mode to exit overcool mode. Another story was that sure it may not work but all I have to do is operate it manually. And the last story, supposedly from the "Engineers in Italy," was that it may be a tolerance issue in the sensing of the battery voltage so why don't I just operate it manually and problem solved. Needless to say, I am very disappointed in Isotherm Customer Support. I requested a replacement circuit board but was refused. Beware fellow sailors!

Jackdaw, I think you have this system also. Does yours actually work? Anyone else have this intelligent thermostat system and does it actually works as advertised?
Hi @RoyS , just saw this.

I have the ISEC unit, and have the opposite problem you have. No matter what I do, it controls at exactly 41.0F, and never goes into cold-store. Calls and emails to the distributor, the company both here and in Italy give wildly differing answers. The unit, compressor and box for sure can go colder, switch it to freezer mode and I can turn my entire fridge into a 0F icecube. Its a mess, and I've given up on messing with it; as the compressor and box are efficient enough for my needs. Would be interested if you ever get it sorted out. Let me know!
 
Feb 5, 2004
3,933
Tartan 3800 Westport, MA
jviss, I salute you for building your own intelligent temperature controller. You are doing exactly what the Isotherm ITC thermostat claims it will do. Great if it only worked as described. Wish you worked for Isotherm because none of their engineers can figure this out.
Thank you for the salute, the compliment. It's really not that complicated. I understand what the Isotherm folks wanted to do, and I would likely hav taken a similar approach, were I designing a volume, consumer product. But I think they reached beyond their competency, with the approach of "let's just connect everything to a microprocessor, and then it's a simple matter of software." And then, they suck at software. it is compounded by recognizing the bug, and trying to document their way out of it. Shameful. If they were smart, they would have approached Inkbird and had them do a special for them, based on the ITC-1000.
 
Nov 8, 2010
10,586
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Mine is the single rotary dial (non led/digital gauge) with an arrow for automatic overcool mode.

Seems to work fine. You do have to set the dip switches correctly, including any "offset" to get it to overcool to the 33 degree measured temperature. Its a little bit of a "trial and error" process.
@smokey73 , Very interesting. Can you send me a picture or illustration of your DIP switches?

Thanks!
 
Dec 23, 2016
130
Catalina 27 Clinton CT
jviss

Are you saying that it is in the software? They kind of bill it as an automatic unit and then waffle on it when pressed
 
Sep 15, 2013
540
Catalina 270 270 Mystic Baltimore
Jackdaw. I have the same unit you have except with a different evaporator coil. Attached is the manual. Dipswitch settings begin on page 15. If you set it to the default refrigerator settings everything should work. Mine works as advertised. My box goes down to 24 degrees F on "overcool" mode and floats up to almost 40 on saver mode. The dip switches are not set correctly from the factory and have to be set in order for everything to work right. There is room to tweak as well if you don't like the initial settings.
To the group. I did a lot of research on these things before I bought mine last year. I never saw the panel described above. The ISEC control for mine is just a dial.
 

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