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 > Testing ARPrvSafe and Fridge operation

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Salvo

California

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Posted: 12/22/13 07:19pm Link  |  Quote  |  Print  |  Notify Moderator

I installed the ARP controller in my MH. The install instructions were straight forward and easy to follow. It takes a good 2 hours to install.

Here's what you get.
[image]

The controller is mounted just below the fridge.
[image]

The temperature sensor is mounted on the heating tube above the AC heating element.
[image]

The ARP controller opens up a relay that cuts power to the Norcold controller.
[image]

I ordered the controller that has the data streaming connector. I can now store temperature data on a laptop. That will be a big benefit in understanding operation of the fridge under various conditions.

Here's the turn-on plot. It takes less than 25 min to get to operation temperature of 360 degF.
[image]

The first on-off-on cycle. There's a little overshoot.
[image]

Multiple cycles and turn-off
[image]

The fridge may not be in equilibrium yet. The first few cycles have about 22 min ON time and 25 min OFF time. No food was in the fridge for this test.

The ARP controller shuts the fridge down when the temperature rises above 444 deg.F.

Sal

pianotuna

Regina, SK, Canada

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Posted: 12/22/13 07:34pm Link  |  Quote  |  Print  |  Notify Moderator

Hi Salvo,

As always, informative. Thanks for posting these results.

Did you happen to note the ambient temperature?


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp hours of AGM in two battery banks 12 volt batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

Old-Biscuit

Verde Valley

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Posted: 12/22/13 08:29pm Link  |  Quote  |  Print  |  Notify Moderator

What were freezer & food section temps?

What temp setting (1-5) was used?

Fairly repetitive ON/OFF cycle.......
And having a shut-off at 444*F is a heck of a lot better than the 750*F Norcold Bandaid Recall Fix.

Be interesting to have a fridge you could destroy by testing it in off level conditions to see the ON/OFF cycle and how much affect off level has on temp rise over time.


Is it time for your medication or mine?


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path1

Varies with weather

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Posted: 12/22/13 10:14pm Link  |  Quote  |  Print  |  Notify Moderator

Thanks for posting. That is exactly what I'm looking for. As several have mentioned RV's have a lot to burn in them. This looks like it will shut off frig at certain temp. This is what I had in mind.
http://www.rv.net/forum/index.cfm/fuseac........d/tid/27198095/srt/pa/pging/1/page/1.cfm

if you can stop something from going 300 degrees to 700 maybe some fires will be eliminated.

(I'm reading 2 page disclaimer right now)

KJINTF

Western Montana

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Posted: 12/23/13 06:23am Link  |  Quote  |  Print  |  Notify Moderator

Sal

Thanks for posting the above data - I have the same frig

Was the test done using propane?
If on electric does the ARP work the same?
Just noticed the data streaming is a USB connection via an external conversion cable - does it output a csv file?

* This post was edited 12/23/13 07:00am by KJINTF *


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Salvo

California

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Posted: 12/23/13 09:20am Link  |  Quote  |  Print  |  Notify Moderator

Answering questions.

Ambient temperature when starting the test at 9am was 53 degF. That was the boiler tube temperature recorded by the ARP unit.

I had the fridge on the "warmest" temperature setting: "1". It would have been great to also record the fridge food section temperature, but it didn't occur to me at that time.

This test was with propane. It should work the same with 120V ac.

I believe the data has tab separated values. The data goes directly into an Excel file. I screwed up my Excel file by initially choosing the newer version of Excel which I didn't have. This caused all sorts of errors when I looked at the file. The ARP package comes with two versions of a Excel files containing macros to acquire the data and do what ever else it does. I don't know what it does as my "operator error" prevented this from happening. I saved the unusable file into a txt file and then imported this data into my version of Excel. Temperature is measured every 2 seconds. That's a lot of data when recording for 6 hours.

I had to purchase the data cable from Digikey for $20. It would have been nice to have a standard USB connector on the ARP unit. It does not. I have seen a photo of a ARP controller with a mini USB connector. I think Paul, the person who sells/designed the controller, envisions everybody purchasing the ARP controller that does not have the data out stream feature. You can also push the display button on the controller to display current boiler temperature on all units.

I plan to do more testing the following weeks while in Baja. If I get a chance, I'll see how off-level affects boiler tube temperature.

Sal

Old-Biscuit

Verde Valley

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Posted: 12/23/13 02:08pm Link  |  Quote  |  Print  |  Notify Moderator

Salvo wrote:

Answering questions.

I plan to do more testing the following weeks while in Baja. If I get a chance, I'll see how off-level affects boiler tube temperature.

Sal


I wouldn't intentionally run a your fridge off level just to gather some data......
Off level will damage an absorption fridge and that damage is accumulative.

IF one had a fridge that was surplus..then I would test it. Not one I had/wanted to keep

Chris Bryant

Arden, North Carolina

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Posted: 12/23/13 02:53pm Link  |  Quote  |  Print  |  Notify Moderator

The ARP is very sensitive- it's interesting how small a tilt it takes to make a measurable rise in boiler temp.


-- Chris Bryant
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Gjac

Milford, CT

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Posted: 12/24/13 08:37am Link  |  Quote  |  Print  |  Notify Moderator

Old-Biscuit wrote:

What were freezer & food section temps?

What temp setting (1-5) was used?

Fairly repetitive ON/OFF cycle.......
And having a shut-off at 444*F is a heck of a lot better than the 750*F Norcold Bandaid Recall Fix.

Be interesting to have a fridge you could destroy by testing it in off level conditions to see the ON/OFF cycle and how much affect off level has on temp rise over time.
Is the Norcold recall fix measured at the same place as the ARP? If it is 300 degrees is a lot more heat? How many inches above the electric element is the temp sensor mounted?

Salvo

California

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Posted: 12/24/13 12:03pm Link  |  Quote  |  Print  |  Notify Moderator

I placed the temperature sensor about 3 inches above the curved tube that contains the ac heating cable.

What's the writing on the wall?

1. 750F is good enough to prevent fires.
2. 750F will probably cause fridge damage.
3. Replacing heating units is a good business for Norcold.

Sal

Gjac wrote:

Is the Norcold recall fix measured at the same place as the ARP? If it is 300 degrees is a lot more heat? How many inches above the electric element is the temp sensor mounted?


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