Fridge Defender for Narcold N180.3 and other units

grassgd

Does anyone have experience with the Fridge Defender sold by ARP to protect overheating of the refrigerator boiler when on propane? 

According to the arprv.com website, when operating on propane, the unit can get too hot and cause damage.  The device they offer appears to offer high temp shutdown of the unit to avoid this damage. 

They also offer the protective device with or without fans to facilitate air flow to aid in the units cooling.  I have been testing my unit to find out what methods improve the units cooling with the addition of a fan or by adding a temporary "flue" to the upper vent opening to aid in natural draft of the unit with or without adding a fan but until reading on the arprv.com website was unaware of the potential for high temps causing damage.

Grumpy_G

While I do *not* have any experience with the product itself I do have experience with a fridge going into what I like to call "overdriven" mode. Several years ago I had a trailer with a fridge that was controlled by an electronic module. The module had failed in a way where it would not turn off the heat source (regardless if gas or AC) when the target temperature was reached, creating an overheat condition of the boiler. The symptom was that the fridge would start to cool just fine for several hours but then overheat and the temperature in the compartment would rise. I probably overheated it 7 or 8 times until I figured it out (the thermistor tested good btw). Replaced the control module and fridge was working fine after that. It did not suffer damage from overheating for 8+ hours overnight. In theory severe overheating causes crystallization of sodium chromate that is added to the absorption cooling system. Maybe newer designs avoid going into the danger zone by limiting the maximum heat. 

In my unsolicited opinion, the fridge defender might have been useful 20 years ago when there were fridges causing fires from overheating. Heck the arprv.com website looks like it's 20 years old . For the N180 and the older 3163 (which are untypical designs) the fridge defender only cuts off the gas supply but does nothing on the AC side. So if the thermostat does not shut off AC power the fridge is still going to overheat. 

RVMike

Yes, I installed one in my last RV.  I might install one on my new 320 s.  (I have other priorities now like a brake controller and some new glycol.) The hardest part of installing the Fridge Defend was removing the fridge (had to cut through silicone glue holding it in.) The installation of the device was easy.  My only reservation with the use of it was that my install had a lot of 'open' (to the boiler) reports to the unit which would then shut down the fridge.  Not all the time, but sometimes.  When that happened, I would just shut down the Fridge Defend. Otherwise, I was happy with its operation.  The coded reports were not especially intuitive, needed to print out the manuals to understand the thing.

The Fridge Defend will shut down the over heating whatever the source, not just LP.  Read their website: "Electric heaters can cause the boiler to overheat in a number of ways. Here are just a few:"

Out of level conditions are the big problem with absorption refrigerators. Fridge Defend will shutdown the fridge when out of level overheats happen.  I guess is that the RV manufactures are switching to compressor refrigerators because of absorption fridge fires.

Grumpy_G

The Fridge Defend will shut down the over heating whatever the source, not just LP.  Read their website: "Electric heaters can cause the boiler to overheat in a number of ways. Here are just a few:"

I can only go by the installation instructions on the arprv web site which clearly show that for the N180 it only controls the LP interrupter. That seems to be the case for all "manual" fridges, presumably because the manufacturer does not want the liability for modifications to the high voltage side. On fridges with control boards the product manipulates the control side to turn off either heat source.