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Old 10-03-2019, 07:48 PM   #21
marklg
 
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Default Re: Vitrifrigo C115IBD4-F-1 Compressor Fridge

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I'm sure it is possible, but I haven't tried. It definitely has enough oomph to get lower temps. I just did not want to freeze stuff in the fridge. Since the thermostat is in the fridge section, it holds that to within +/- 1 degree F. The freezer is held to +/- 3.5 degrees.

I expect if the divider was insulated, the freezer would vary even more. So the fridge would be 40 +/-1 and the freezer would be maybe between 0 and -10. You can't hold both at very precise temps without two compressors or something else to actively control the relative temps.

I also expect if more insulation was added between the freezer and fridge, it may be a little less efficient and the fridge temp may even vary more than +/- 1 degree. I might try something to see. It might even get the freezer colder if frost starts to build up in the freezer. That is somewhat of an insulator. There is a frost tray below the freezer. Some insulation could easily fit in there and not take up any space. Maybe I'll take a look at that.

I don't detect any fans inside the unit.

Regards,

Mark
I did try putting insulation in the tray below the freezer. I tried a piece of 1/2" iso in the back 1/2 of the tray and the front 1/2 of the tray. The results were not as expected. The fridge temps went up to 39 +/- 1 F and the freezer swung between 3 and 10 F. I don't consider that a big improvement and am confused as the thermostat control is at the bottom of the fridge in the back. I would have expected the freezer to go down and the fridge to keep the same temperature. I've got a question into their support and will see what they suggest.

Regards,

Mark
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Old 10-03-2019, 07:56 PM   #22
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Default Re: Vitrifrigo C115IBD4-F-1 Compressor Fridge

The knob may be at the back of the fridge, but the capillary tube (the temp probe) is almost certainly mounted just below the evap plate. Thats why the fridge got warmer.

You can swap to a fridge calibrated thermostat with the cap tube in the fridge area. Or even a digital thermostat if desired. Combined with insulation on the freezer side it can result in a decently cold freezer.
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Old 10-03-2019, 09:04 PM   #23
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Default Re: Vitrifrigo C115IBD4-F-1 Compressor Fridge

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Originally Posted by Midwestdrifter View Post
The knob may be at the back of the fridge, but the capillary tube (the temp probe) is almost certainly mounted just below the evap plate. Thats why the fridge got warmer.

You can swap to a fridge calibrated thermostat with the cap tube in the fridge area. Or even a digital thermostat if desired. Combined with insulation on the freezer side it can result in a decently cold freezer.
You mean this?

Thermo.jpg

So, the thermostat does measure the temp below the evap plate, the freezer varies a lot and the fridge varies a little due to thermal mass? I guess that does make sense.

So, I will just put insulation below the evap plate and turn the thermostat down. That should result in a colder freezer and the same temp in the fridge. Trying that next. This is a brand new fridge under warranty. Don't want to modify it just yet.

Regards,

Mark
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Old 10-03-2019, 09:14 PM   #24
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Default Re: Vitrifrigo C115IBD4-F-1 Compressor Fridge

No worries. Most of those fridges use simple spade connectors at the thermostat, which is mechanical. You can get a 25$ 12V temp controller on Amazon. Then just disconnect the terminals from the existing thermostat, and connect to the relay terminals on the temp controller. The temp probe for the new thermostat can be run into the fridge past the seal for testing purposes. No permanent mods needed.

Putting a bit of foam between the cap tube and the evap plate will cause the fridge to cycle less often. This will result in larger temp swings in the freezer, but the average temp will be lower without a significant change in power consumption.
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Old 10-04-2019, 08:26 PM   #25
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Default Re: Vitrifrigo C115IBD4-F-1 Compressor Fridge

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I remember seeing a spec of 40 Ah per day for this fridge, but can't find that reference again. It seems right at that number. It uses 45 Watts, so it is on about 1/2 the time.
That's good to know. I've seen where several manufacturers are saying 25% is a good estimate for the duty cycle. I have been using the 25% in my calculations and will now modify to 50% (1/2 time). This increases my overall total load by ~10% (refrig goes from 10% to 20% of the total).
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Old 10-04-2019, 09:00 PM   #26
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Default Re: Vitrifrigo C115IBD4-F-1 Compressor Fridge

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That's good to know. I've seen where several manufacturers are saying 25% is a good estimate for the duty cycle. I have been using the 25% in my calculations and will now modify to 50% (1/2 time). This increases my overall total load by ~10% (refrig goes from 10% to 20% of the total).


Thought I read somewhere that Danfoss compressors run for 21 minutes out of each hour. My Isotherm uses about 60 watts when running.


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Old 10-04-2019, 10:47 PM   #27
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Default Re: Vitrifrigo C115IBD4-F-1 Compressor Fridge

Another reference point: I installed a Danfoss compressor in my Edgestar POS fridge body. It runs 33% duty cycle at 75F ambient. Draws 4.2 amps when on (12V nominal system)
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Old 10-05-2019, 07:37 PM   #28
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Default Re: Vitrifrigo C115IBD4-F-1 Compressor Fridge

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Another reference point: I installed a Danfoss compressor in my Edgestar POS fridge body. It runs 33% duty cycle at 75F ambient. Draws 4.2 amps when on (12V nominal system)
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Originally Posted by gltrimble View Post
Thought I read somewhere that Danfoss compressors run for 21 minutes out of each hour. My Isotherm uses about 60 watts when running.
So maybe 33% is a closer estimation for typical 12v refrigerator duty cycle? For design purposes I may go just a tad more conservative though. I'm looking at a Vitrifrigo model DW210IXD4 that draws 61W when running so it's not exactly inconsequential.
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Old 10-05-2019, 08:56 PM   #29
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Default Re: Vitrifrigo C115IBD4-F-1 Compressor Fridge

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Originally Posted by bsqr View Post
So maybe 33% is a closer estimation for typical 12v refrigerator duty cycle? For design purposes I may go just a tad more conservative though. I'm looking at a Vitrifrigo model DW210IXD4 that draws 61W when running so it's not exactly inconsequential.
With all the testing I've done, it has always been between 40-50% runtime with a 75-77 F outside temp and some added insulation.

Regards,

Mark
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Old 10-05-2019, 09:24 PM   #30
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Default Re: Vitrifrigo C115IBD4-F-1 Compressor Fridge

My NovaKool 9.2 cu.ft. refer has been running for a couple of months now. It has the Danfoss "35" compressor. I have been keeping pretty close tabs on it as it's sitting in the driveway running continuous.

It has been loaded with a couple of water/ice jugs in the freezer and fridge along with a 12-pack and some bait.

What I am seeing is 550 watt hours consumed in 24 hour period.

So, 550 / 24 = 22.91 watts per hour.

Running I see between 56 and 70 watts. Specs say it should be 64 watts, or 4.8amps. I think my numbers vary at start up etc.

I think that all this is telling me it's running about 36% of the time?

I love this fridge. 33/6 degrees constant and batteries are back to 100% by 11AM
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