Trial of a new type of RV fridge controller

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Gary RV_Wizard

Site Team
Feb 2, 2005
West Palm Beach, FL
I've been discussing the Norcold fire problem and similar fridge temperature issues on other brands with Paul Unmack, a consulting Process Control engineer and RV owner. Paul has developed a temperature sensor and controller module that monitors and regulates the temperature of the boiler in an absorption fridge more closely than the factory controllers. Equally important for the Norcold 1200's, his monitor prevents the boiler tube from ever getting so hot that a shutdown is necessary. It automatically cuts it off well short of the danger point and restarts once it cools.

Basically the Norcold recall box lets the temperature soar to near 800 degrees F. before irrevocably shutting down. At that temperature it is pretty much conclusive that the cooling unit has failed.  However, Paul contends that operation above about 200 degrees C. (about 390 F.) is totally unnecessary for good cooling action and that the boiler can be controlled to much lower temperatures.  These videos are a bit techie but it describes what happens in the fridge boiler and how it can be controlled better.

Paul is looking for a small number of people for some further testing and reporting on his controller module, which he hopes to put into production soon. The primary purpose of this is to gather data on the temperature ranges encountered in normal fridge usage by a varied population of RVers.  To do that, he wants to install both the controller and a data gathering module in more Rvs.  I'm going to have one installed on my Norcold and I am extending an invitation from Paul to others on this group who might be interested in doing the same.  I think he may be willing to install it even if you don't want to participate in the data gathering, but there would probably be a modest charge for the device.

I have no financial interest in this device but the concept is intriguing to me. Doesn't seem to be any real risk in giving it a try.
I know he is working on Nocold refers, but is the same controller applicable to Dometic.  I would think it would be as the systems are similar.
I would be interested in testing a Dometic version too.
Paul says his controller works with any absorption fridge, though of course the wiring to tie into the standard controller will differ slightly. It's really a boiler tube monitor, so is an adjunct to the factory system. It doesn't replace the Norcold "recall" fire safety box either, though presumably the recall module could never see a valid overheat condition once the ARP module is installed.

I'm pretty sure he has at least one Dometic model using the ARP unit, but I'll ask. What Dometic models do each of you have?
I would we willing to help with data collection. I have a Amish cooling unit in my Norlcold RIM1201.
I'll pass all your names onto Paul Unmack. I'm not sure how many volunteers he is looking for, or how many he will be able to support with trial units. He is hoping to have production-level ARP modules available sometime in September, so nothing would happen before then.
Gary RV Roamer said:
I'm pretty sure he has at least one Dometic model using the ARP unit, but I'll ask. What Dometic models do each of you have?

I have the 1062 with the mods in it from 2009, November If I remember correctly.
My Dometic is working fine with all the updates, but I would certainly entertain purchasing the aftermarket monitor/controller as a safety precaution and with the expectation that removing 600 degrees of over temp before shut down would extend the lifespan of the fridge.

Whether or not it was declared as a sale point, that's what I would expect as a by product of keeping the maximum temperature down and that seems a worth while expense.

Beta me if he wants, I'm open to it. If not, I'll be watching the marketplace.

I have the Dometic RM 2652
I'm interested, it sounds like a good option for a Demotic RM7130, especially for us full timers.

Thanks for the interest. He is looking for a dozen or so volunteers and I think we have more than that so far from this site and the American Coach Owner Club, which also was invited to participate.

I think that the production ARP unit will have suggested retail of around $120. Early testbed users will get a much better deal than that (tbd), and their unit will include a data collection cable that will plug data into a spreadsheet via a CSV file. Users would be expected to send in their data files periodically.  There is a possibility that there may be some discounted early units without data collection, but nothing decided yet.

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