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Hoghead 28-04-2018 01:28

Freezer thermostat - analogue or digital?
 
I am changing my fridge set up from fridge + freezer with individual holding plates, to a spillover system with both holding plates in the freezer

Thermostats are both analogue
I understand I need a freezer thermostat to replace the fridge one

Is there any benefit to change to digital thermostats and will I see any noticeable gain?

Can one thermostat control both compressors or do they need individual controls?
I suspect not but worth asking........

Is there a dual channel digital thermostat?

I have 3 digital controllers, with one to turn the spillover fan on and off as required, and as a bonous give me digital temperature readout in the fridge.
Another will give me digital readout in the freezer, so that advantage of the digital thermostat is moot

I was told here that these controllers will not replace the thermostat. I still do not understand why these controllers cannot use their set points and integral 20A relay to turn on the BD50 compressors?

travellerw 28-04-2018 05:34

Re: Freezer thermostat - analogue or digital?
 
I just installed an Inkbird digital thermostat on my freezer. Its only been about 2 weeks, but so far its been fantastic.

https://www.amazon.com/Inkbird-All-P...nkbird+digital

It gives you the option to attach the sensor whereever you want in the cabinet, or on the plate.

If I was in your situation, I would be tempted to try and control both compressors with one unit. According to the documentation on my compressors, the control circuit is a resistive sensing circuit with 15ma of current on the wire. I would be temped wire the "C" wires together on one relay input, then wire the "T" wires together on the other relay input. However, you might have an issue with each controller "seeing" the other controller and running continiously.

A better solution would be to use the Inkbird to control 2 separate automotive relays. Then those relays could control each compressor. Your total investment would be under $25.

Maybe one of the refrig specialists will join in and call me an idiot. However, until then, that would be my plan if I was in your situation.

OzePete 28-04-2018 05:36

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by Hoghead (Post 2623035)
I am changing my fridge set up from fridge + freezer with individual holding plates, to a spillover system with both holding plates in the freezer

Thermostats are both analogue
I understand I need a freezer thermostat to replace the fridge one

Is there any benefit to change to digital thermostats and will I see any noticeable gain?

Can one thermostat control both compressors or do they need individual controls?
I suspect not but worth asking........

Is there a dual channel digital thermostat?

I have 3 digital controllers, with one to turn the spillover fan on and off as required, and as a bonous give me digital temperature readout in the fridge.
Another will give me digital readout in the freezer, so that advantage of the digital thermostat is moot

I was told here that these controllers will not replace the thermostat. I still do not understand why these controllers cannot use their set points and integral 20A relay to turn on the BD50 compressors?

Digital temperature controllers are a far better option than old vague mechanical types. For a start they are very accurate, you can properly set the cut out temperature and the hysteresis (or cut-in) and you have the bonus of a temperature read out.
Whoever told you they can't replace a thermostat is wrong because the ARE a thermostat! They can be used in any application where temperature control is needed and that includes controlling the old Danfoss and now Secop BD50 compressor range. Better still they can be remote located.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

Paul L 28-04-2018 09:19

Re: Freezer thermostat - analogue or digital?
 
OzePete,
What digital thermostat do you recommend?

sy_gilana 28-04-2018 10:06

Re: Freezer thermostat - analogue or digital?
 
Totally go digital. Programmable hysteresis, they are the best change you can make.

I installed these... $40.00

AKO - Thermostat / Controller (Panel)

OzePete 28-04-2018 15:37

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by Paul L (Post 2623206)
OzePete,
What digital thermostat do you recommend?

As the previous poster said..
The Elitech STC-8080 12VDC controller suits your job but if you can find an Elitech STC 600 12VDC controller they are better (But near twice the price) as they are water proof and have remote relay. We use the STC 600 Elitech only now and being water proof has made them near 'bullet proof'
The digital controller can be located anywhere and the probe wires extended to suit so if you choose the STC8080 you can locate in a good dry space.
BTW, if you have a 110 or 240VAC Elitech controller you can slide the cover off and remove / bypass the tiny transformer so it will operate from 12VDC.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

Hoghead 28-04-2018 21:02

Re: Freezer thermostat - analogue or digital?
 
I have three of these - 12V and an internal 20A relay

https://www.aliexpress.com/item/W323...311.0.0.Fk9DWF

Cheap enough to throw away if the Elitech or other brands are really any better.

One for the fridge spillover system controlling a computer fan at 0.3A
Easy enough

Another was planned for the 2 compressor + 2 holding plate system in the freezer.
The third is either a spare, or to control the second compressor in the event that using a single controller is a bad idea

Hoghead 28-04-2018 21:19

Re: Freezer thermostat - analogue or digital?
 
Lots of them with a 2 relay output x 12 VDC:

https://www.aliexpress.com/wholesale...o+relay+output

Can one not simply connect each individual relay to its own BD50 compressor?

I will have a circulation fan in the freezer compartment so hopefully both holding plates will be at similar temperatures

They all seem to have cool on one relay and heat on the other. Not sure if the set points could be entered so that one could use both in "cool" mode

OzePete 28-04-2018 21:28

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by Hoghead (Post 2623464)
Lots of them with a 2 relay output x 12 VDC:

https://www.aliexpress.com/wholesale...o+relay+output

Can one not simply connect each individual relay to its own BD50 compressor?

I will have a circulation fan in the freezer compartment so hopefully both holding plates will be at similar temperatures

They all seem to have cool on one relay and heat on the other. Not sure if the set points could be entered so that one could use both in "cool" mode

Hi HH,
Regardless of brand I think you will find that Elitech manufacture all of those. We use their STC600 because it is waterproof and supplied with twin remote relays.
They usually have SPDT switching so you should be able to control two systems with one device but why bother when they are so cheap! Also with two devices you get to have two temp monitors at all times.

Cheers OzePete

travellerw 29-04-2018 04:11

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by Hoghead (Post 2623464)
Lots of them with a 2 relay output x 12 VDC:

https://www.aliexpress.com/wholesale...o+relay+output

Can one not simply connect each individual relay to its own BD50 compressor?

I will have a circulation fan in the freezer compartment so hopefully both holding plates will be at similar temperatures

They all seem to have cool on one relay and heat on the other. Not sure if the set points could be entered so that one could use both in "cool" mode

Those are the exact same unit I linked to on Amazon (branded Inkbird).

First.. Although they say 2 relay, one relay is for heating and one is for cooling. I have found no way to make both relays operate as cooling relays (without physical modification). However it would be trivial to cut a trace on the board and run a jumper wire to make both cooling relays.

Second.. You need to look closely at the descriptions. Some of these devices have a "delay" setting and some don't. You NEED the "delay" setting. It prevents the unit from trying to cycle the compressor on too quickly before the pressure has equalized.

I took mine apart before installation. Although its not "waterproof", the board was conformally coated. Pretty hard to beat at $15 shipped directly from Amazon's warehouse, with Amazon's warranty.

Cpt Mark 29-04-2018 10:02

Re: Freezer thermostat - analogue or digital?
 
Chiming in with another question. I have an old 110V 3/4 hp motor dual plate, dual cabinet system with analog thermostats.. One side gets and maintains its chill and then the entire system shuts down where both sides should run independently. Not sure why this is happening but I suspect a faulty thermostat. I will test this and assuming that is the case could I replace both thermostats with one of these?

Origin Elitech ECS-180neo 110V Digital Temperature Controller Centigrade Thermostat w Sensor

Hoghead 29-04-2018 21:51

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by travellerw (Post 2623565)

Second.. You need to look closely at the descriptions. Some of these devices have a "delay" setting and some don't. You NEED the "delay" setting. It prevents the unit from trying to cycle the compressor on too quickly before the pressure has equalized.

Mine are single relay units so one for each compressor. Or I could splurge and buy a cheap dual relay unit and cut and jump the trace as you suggest

Delay is programmable from 0-10 min.
What is an appropriate delay?

SV THIRD DAY 29-04-2018 22:39

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by Hoghead (Post 2624014)
Delay is programmable from 0-10 min.
What is an appropriate delay?

Typical is 3 min.

OzePete 29-04-2018 22:40

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by Hoghead (Post 2624014)
Mine are single relay units so one for each compressor. Or I could splurge and buy a cheap dual relay unit and cut and jump the trace as you suggest

Delay is programmable from 0-10 min.
What is an appropriate delay?

3 minutes should see your system balance out for a zero load start

Sorry Rich, didn't notice your prior post...

SV THIRD DAY 30-04-2018 07:19

Re: Freezer thermostat - analogue or digital?
 
That's called a Double Blind Answer Confirmation from two Eutectic Holding Plate guys....ha ha ha....:)

Cheers Pete

travellerw 30-04-2018 08:05

Re: Freezer thermostat - analogue or digital?
 
Thanks for posting Pete and Rich.. I had a local guy tell me 6 minutes.. I guess I will be adjusting it down.

patprice 08-06-2020 22:32

Re: Freezer thermostat - analogue or digital?
 
Old thread I see but all above discussion revolves around a BD50. Is it all aplicable to my BD35?

SV THIRD DAY 08-06-2020 22:38

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by patprice (Post 3159594)
Old thread I see but all above discussion revolves around a BD50. Is it all aplicable to my BD35?

Yes....the BD50 and BD35 use the exact same controller and thermostat.

patprice 08-06-2020 23:02

Re: Freezer thermostat - analogue or digital?
 
Thanks SVTD I will give a digital thermo a try.
Have ordered this one....
https://www.ebay.com.au/itm/12V-All-...72.m2749.l2649

Outventure 19-07-2021 05:01

Re: Freezer thermostat - analogue or digital?
 
i have issues with my freezer and thought i'd ask here before opening a new thread.
I have an isotherm freezer and it's a nice stainless steel inside unit that I rather repair instead of replacing. It works, but doesn't freeze below -3°C (26° F)
So I had already 3 fridge mechanics on the boat who installed additional fans, replaced the gas and finally I ordered a brandnew compressor and controller (BD50) and had it installed. Even now it doesn't go below the above mentioned temperature. So the last thing i may replace on the unit is the thermostat. I already have that inkbird digital 12V one, but my last fridge mechanic didn't want to install it. (wasn't capabable i guess). Where i am, there isn't much of a choice of marine mechanics.. (Panama Pacific Westcoast).

I am in Europe at the moment and may order a manual Vitifrigo Thermostat, however, i would love to hear some feedback from people who ordered and installed one of these digital thermostats. Did you get your fridge / freezer to work better?

Thanks so much for any help!

Bill O 19-07-2021 05:57

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by Outventure (Post 3447307)
I am in Europe at the moment and may order a manual Vitifrigo Thermostat, however, i would love to hear some feedback from people who ordered and installed one of these digital thermostats.


See link in response #19 above. This will work as a digital thermostat and will be much cheaper than a Vitifrigo thermo.

Outventure 19-07-2021 06:11

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by Bill O (Post 3447342)
See link in response #19 above. This will work as a digital thermostat and will be much cheaper than a Vitifrigo thermo.

Thanks Bill. I have that thermostat (the amazon inkbird version) already as I've read that it may work, however I was looking for a confirmation of someone who has actually installed it on his fridge / freezer. May i ask if you have done so?

Bill O 19-07-2021 06:26

Re: Freezer thermostat - analogue or digital?
 
Not on an Isotherm, but for a fridgoboat freezer (should be the same though w/a BD50).

Biggest thing is to set your range so it moderates the frequency of the compressor turning on/off.

Was your old thermo for a fridge? Shouldn't be too hard to put in the inkbird to test if it just a wrong/bad thermostat.

If that doesn't do it, would open a new thread and get Richard involved after you discuss specific symptoms. (is the tube coming out of the box freezing?, amp draw, etc.)

Richard Kollmann 19-07-2021 08:12

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by Outventure (Post 3447307)
i have issues with my freezer and thought i'd ask here before opening a new thread.
I have an isotherm freezer and it's a nice stainless steel inside unit that I rather repair instead of replacing. It works, but doesn't freeze below -3°C (26° F)
So I had already 3 fridge mechanics on the boat who installed additional fans, replaced the gas and finally I ordered a brandnew compressor and controller (BD50) and had it installed. Even now it doesn't go below the above mentioned temperature. So the last thing i may replace on the unit is the thermostat. I already have that inkbird digital 12V one, but my last fridge mechanic didn't want to install it. (wasn't capabable i guess). Where i am, there isn't much of a choice of marine mechanics.. (Panama Pacific Westcoast).

I am in Europe at the moment and may order a manual Vitifrigo Thermostat, however, i would love to hear some feedback from people who ordered and installed one of these digital thermostats. Did you get your fridge / freezer to work better?

Thanks so much for any help!

I would like to point out a thermostat only stops and starts compressor and low box temperature is determined by how long compressor is allowed to run.

The evaporator inside box and the refrigerant flow control ( probably Capillary tube ) determines limited Btu output of compressor. So there is a good chance a larger BD50 will not improve that units performance.

I would suggest two tests, Bypass present thermostat so compressor runs continuous to see how cold the freezer will get in 4 hr, 6 hr or when desired box temperature is reached. If this compressor is a BD35 then I would see that it is running at max speed of 3500 Rpm.

It this box's heat to be removed is too large for evaporator to handle a fan moving air across evaporator plate offer a lower box temperature but not normal low freezer temps of 8 to 15 degrees F.

An amp reading after unit runs for 30 minutes with box temperature will determine amount of work done at that moment.

Outventure 19-07-2021 08:34

Re: Freezer thermostat - analogue or digital?
 
Thanks Richard for the feedback.
Ok, i will run these tests that you mentioned. thanks.
Just as a conclusion for my immediate question: that inkbird digital 12v thermostat would be the right choice, also over a mechanical original one.

I got the BD50 as the old one was also a BD50. I am in tropical temperatures (around 32 C / 90 F most of the time) and I really need that freezer for the fish that we catch ;) . Also I've invested already too much to just stop now and I can't see a reason why I wouldn't get it to work with that brandnew compressor / controller..

Richard Kollmann 19-07-2021 14:54

Re: Freezer thermostat - analogue or digital?
 
Quote:

Originally Posted by Outventure (Post 3447461)
Thanks Richard for the feedback.
Ok, i will run these tests that you mentioned. thanks.
Just as a conclusion for my immediate question: that inkbird digital 12v thermostat would be the right choice, also over a mechanical original one.

I got the BD50 as the old one was also a BD50. I am in tropical temperatures (around 32 C / 90 F most of the time) and I really need that freezer for the fish that we catch ;) . Also I've invested already too much to just stop now and I can't see a reason why I wouldn't get it to work with that brandnew compressor / controller..

I am not the one to ask about electronic thermostats especially on refrigeration using evaporator temperature controlled thermostats. I do recommend an adjustable remote thermometer calibrated for area where frozen fish are kept.
I lived in tropical weather 30 years with both my boats 12 volt refrigeration systems running at my dock. On your freezer I would expect to see amp flow of 6 to 6.5 until box temperature is below +15 degrees. Assuming compressor is running at max speed. The current across thermostat to get max speed is 5 milliamps.

I have had six cu ft freezer system designs using BD50 compressors that run in hot weather almost 100% of the time maintaining 4 to 8 degrees F freezer temps.

Bill O 19-07-2021 16:17

Re: Freezer thermostat - analogue or digital?
 
1 Attachment(s)
Quote:

Originally Posted by Outventure (Post 3447461)
Just as a conclusion for my immediate question: that inkbird digital 12v thermostat would be the right choice, also over a mechanical original one.

Attached is the Frigoboat MkII electronic thermostat hook up instructions which is basically the inkbird controller in cooling mode.

Still wanted to know if a tech filled your system, possibly overfilled it and maybe part of your problem. Is the line coming out of the box going back to the compressor frozen/heavily frosted?

Do what Richard suggested to test to see if you system can pull the temp down.

Outventure 13-08-2021 12:31

Re: Freezer thermostat - analogue or digital?
 
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..)

alaskanviking 13-08-2021 16:50

Re: Freezer thermostat - analogue or digital?
 
took me a little bit but i found the article

https://seabits.com/save-battery-bee...dge-optimizer/

Haven't heard anything lately on it, and i cant check the product website here at work

Outventure 13-08-2021 17:58

Re: Freezer thermostat - analogue or digital?
 
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!

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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