Testing ARPrvSafe and Fridge operation

Chris Bryant wrote:
One thing to keep in mind- the ARP is designed and calibrated to shut down before damage occurs- if you read the technical docs, it shuts down when the boiler temp is over what a properly operating unit would be- the only way the boiler temperature would be that high is if it is starved for ammonia. Keeping the unit from catching fire is just a side benefit :)
The OEMs really should have this installed from the factory- the technology integrated in to the control unit would be far superior to anything they have now.

It is my understanding that the designer/inventor of the ARP did approach Dometic and Norcold with this device but in BOTH cases was flatly turned down.

You see, if the CU is proactively monitored and cared for they (the fridge companies) would SELL LESS fridges and CUs as REPLACEMENTS.

This in turn would be reflected in their bottom line in reduced sales and profits. You bet they are making a killing in aftermarket sales by allowing a higher off level spec and higher boiler temps...

One thing to keep in mind- the ARP is designed and calibrated to shut down before damage occurs- if you read the technical docs, it shuts down when the boiler temp is over what a properly operating unit would be- the only way the boiler temperature would be that high is if it is starved for ammonia. Keeping the unit from catching fire is just a side benefit :)
The OEMs really should have this installed from the factory- the technology integrated in to the control unit would be far superior to anything they have now.

Thanks for posting this information. Knowing the results of your testing I suppose one could just put a remote temp probe there and monitor for temps in excess of 444 degrees. Going a little further one could adjust the leveling jacks for the lowest temps then set the bubble to the temp reading. Have a Merry Christmas.

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?

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?

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

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

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

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?

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/fuseaction/thread/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)