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-   -   Freezer thermostat - analogue or digital? (https://www.cruisersforum.com/forums/f115/freezer-thermostat-analogue-or-digital-200513.html)

OzeLouie 13-08-2021 18:36

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by Outventure (Post 3462889)
Thanks again for the info and feedback.
I‘m back on my boat and bridged the thermostat and have the compressor running now for a continous 6 hours.
Temp doesnt go below -2 C / 28 F.
The line that‘s coming out of the unit is not frosted.
Totally clueless now and very frustrated.
If you have any idea what to do i‘d very much appreciate, otherwise i‘ll probably have to order a mobile freezer box. (Which im thinking that i should have done before throwing money at a new compressor..)

Provided the evaporator is frosted all over and the suction line is not, as reported, then the six hour constant run is as good as its going to be in your warm environment.
Adding any devise will not improve that, the system and or cabinet are not up to the task.

If you could advise the model number I will engineer the heat load, duty cycle and power consumption that your system should achieve to confirm if your system is operating correctly or not.

Also suggest you run your hand over the freezer cabinet outer skin looking for any 'cool patches that would indicate poor insulation?

Richard Kollmann 14-08-2021 06:07

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by Outventure (Post 3463061)
Thanks Alaskanviking!
This looks really awesome and like an addition to the freezer that I would love to have. However, I've already thrown a few hundred bucks at this freezer and before spending another 300 (what this unit seems to be) i'd love to know if that will really solve my problem.. i will get in touch with the producers, though. thanks a lot for giving this idea, I haven't heard of this device yet (and i have to admit I would love to get it only because of it's cool name ;) ):
cheers!

I have not seen any evidence in in your reporting that the compressor is delivering correct level of performance. True performance of your compressor can only be determined by amperage draw of compressor. Box temperature relates to evaporator's lowest temperature. This is why most small refrigerators thermostats control evaporator temperature. Lack of insulation with compressor at maximum performance with thermostat bypassed will result differently than you report.

Necessary missing information from your posts, Amperage draw of system and compressor manufacture model.

Outventure 18-08-2021 12:15

Re: Freezer thermostat - analogue or digital?
 
1 Attachment(s)
Ok. So i've installed the digital thermostat and after a while the temp inside the box went down to -7 degrees. That's at least enough for some icecubes for some rum and coke to cool me down ;) . And the digital thermostat is a nice thing to have actually. you can not only set the target temp , but also the temp range (so that you can adjust when / how often you want the compressor to start again) and it's nice to follow with my Bluetooth thermometers in the fridge.

In case anyone is wondering, the thermometers were 10 dollars each from Amazon, "govee" is the brand. Not sure how long they will last, but I put one in each of my fridges.

Next step is to increase the rpms of the compressor. So i've ordered 600 and 1500 ohm resistors that I will put in.

Will keep you updated! thanks so much for all the input, I really appreciate!

Bill O 18-08-2021 13:10

Re: Freezer thermostat - analogue or digital?
 
So in general it was a problematic thermostat all along!? Increasing the rpm should help get the temp lower.

Would be nice to experiment to find out which rpm was the most efficient at power consumption while getting the temp down lower.

Do you have any way to monitor the amp usage? We have one of these on our fridge and freezer compressors to monitor energy usage.

Outventure 18-08-2021 13:21

Re: Freezer thermostat - analogue or digital?
 
well, i have replaced the whole compressor unit and had a technician put new gas (hopefully in the right amount). i really can't say if the old compressor would have worked better with the new thermostat and it's nothing I could easily install back.
i will keep it though and maybe at some point use it for my small outside waeco fridge..
i will experiment with the resistors, however I only ordered 600 and 1500 ohms which will result in 3000 or 3500 rpms.
checking and optimizing the energy consumption is another level, for now my primary goal is to get it to properly freeze. but maybe i will get there one day ;)

Bill O 18-08-2021 13:47

Re: Freezer thermostat - analogue or digital?
 
Found this older PS article describing what I was suggesting as an experiment.

The Frigoboat speed board would have only given you the extra 2500 rpm setting (over the 2000 rpm I assume you are running now) than 2 resistors (3000 and 3500 rpm) that you have already ordered. While possibly easier to change rpm settings, the frigoboat board is probably more expensive.

Networker 18-08-2021 14:03

Re: Freezer thermostat - analogue or digital?
 
Dumb question but wouldn’t a freezer at 28f or 22f be ok? I just put one in my boat and still building the spillover wall, but right now it runs at 22f and everything inside is frozen solid. Once I put the spillover wall in place I presume it will go colder, but is it necessary?

OzeLouie 31-08-2021 18:38

Re: Freezer thermostat - analogue or digital?
 
Again, digital thermostats are the way to go for many reasons and one that hadn't been mentioned here yet... Digital thermostats are extremely accurate as they are not effected by the environment they are located in whereas most mechanic thermostats are. Most mechanical thermostat are not 'ambient compensated', the reason they are normally located inside the refrigerated cabinet and not outside! It's a 'no-brainer.. really unless you're a masochist who prefers a crank handle to a starter motor!! :banghead: :biggrin:

Cheers Louie

Richard Kollmann 01-09-2021 08:59

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by Networker (Post 3465745)
Dumb question but wouldn’t a freezer at 28f or 22f be ok? I just put one in my boat and still building the spillover wall, but right now it runs at 22f and everything inside is frozen solid. Once I put the spillover wall in place I presume it will go colder, but is it necessary?

The US Agriculture has posted on line many limits for storing defer-ant frozen food by month. Their maximum temperature for transporting frozen food is 24 degrees F. Temperatures stated in report do not indicate spoilage but flavor quality. If boat freezer evaporator does not surround product it needs to be rotated in box regularly. On any refrigerated area there needs to be air circulation around and under product in box, this is usually achieved in freezer by small wood rails running down from evaporator and across box's bottom and up the other side guiding the natural tumbling of warm air to evaporator.


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