Fire Safety Product
Learn about the Fridge Defend from ARP and how it is designed to prevent RV refrigerator fires.
By Steve Froese, F276276
In the November-December issue, I wrote about the idea of helping to keep your RV and your family safe while traveling by installing a fire suppression system. Continuing the theme of fire safety, in this issue I’ll discuss a way to guard against RV refrigerator fires.
Many RV owners have heard stories of RV fires involving an absorption-type refrigerator, and some have experienced such a fire themselves. RV refrigerator manufacturers Dometic and Norcold both had extensive RV recall campaigns in the early 2000s. Both manufacturers have made improvements to their units, but issues can still occur.
The cooling units in these refrigerators use highly flammable chemicals (hydrogen, sodium chromate, and ammonia). If these substances escape and contact the nearby fridge heat source, fire can result. Cooling unit failures can occur due to a combination of welding stress concentration and internal corrosion.
The Fridge Defend incorporates a temperature probe on the boiler tube that signals the device to shut down the fridge as needed and then restart it when safe to do so.
Even in the absence of a catastrophic fridge failure, normal RV travel occurrences such as driving up a hill, parking off level, poor fridge ventilation, a flat tire, or a leveling jack sinking into the ground can result in an absorption refrigerator overheating.
Absorption fridges operate using fired boilers. In other industries, standard practice generally mandates the use of monitoring systems to avoid thermal runaway (a loss of temperature regulation, resulting in an uncontrolled increase in temperature). The Fridge Defend by ARP, a product designed for RV absorption refrigerators, utilizes advanced controls monitoring and self-testing to meet this requirement.
I decided to install a Fridge Defend in my refrigerator compartment instead of a fire suppression system. Owners could install both for optimum protection. The Fridge Defend will shut down an absorption refrigerator if the boiler tube reaches temperatures outside the safe operating range. It monitors the corrosion reaction rate, which depends on temperature and flow conditions. Flow conditions determine the production of refrigerant by the boiler in absorption RV refrigerators.
The Fridge Defend will restore power to the refrigerator once the operating temperature returns to normal. This is unlike the Norcold system, for instance, which will lock out the controls system if an over-temperature instance occurs, requiring a manual reset of the system.
Why is an automatic restart important, though, if a cooling system failure occurs? Surely, we wouldn’t want the fridge to restart in this case. Consider a situation where you are parked on an incline, even a slight one, and have not taken the time to level your RV. In this example, the heat from the energy source will flow straight up rather than through the center of the burner tube, since the tube is not perfectly vertical. This can easily result in the burner tube overheating, even though the cooling unit has not failed.
Relying on a Norcold recall kit, the burner tube would heat up beyond the safe operating temperature parameters, and the temperature sensor would detect this and lock out the control system for the fridge. Once the RV is level again, we assume that the fridge can be safely operated. However, with the recall kit in place, unless the owner knows how to reset the control system, a visit to an RV service center would be required. This can throw a wrench into your travel plans for sure.
Another thing to mention is that with the factory design, the systems shut down at a very high temperature (1,200 degrees Fahrenheit/649 degrees Celsius), so if they do happen to lock out, irreversible damage may have occurred to the cooling unit as a result of the high lockout temperature.
The Fridge Defend by ARP uses advanced controls logic to monitor cooling unit temperature. It will temporarily shut down a fridge in the event of overheating and then start it up again if and when it is safe to do so. The temperature threshold on the Fridge Defend is much lower than that of the original-equipment-manufacturer systems, meaning shutdown occurs at a temperature much higher than normal operating temperature but still well below that which could cause damage to the system.
ARP was founded by Paul and Mao Unmack, a husband-and-wife duo who are both engineers. They were not satisfied with the temperature monitoring utilized by Norcold and Dometic and decided to apply their engineering knowledge and experience to designing and building a “better mousetrap.” The result is a refrigerator over-temperature protection unit that uses complex algorithms to provide safe and reliable fridge temperature monitoring.
Installation is quite straightforward and should take less than one hour for anyone with basic DIY skills. I rate the difficulty level of the installation procedure as two on a scale of one to five.
You can purchase a Fridge Defend unit online at the ARP website – arprv.com. The product is available in two main configurations: with cooling fans or without. The website contains vast amounts of information regarding how the system works, as well as plenty of historical information related to the reason behind the refrigerator recalls that occurred and the solutions implemented by the manufacturers.
Besides these page links, the website also has installation instructions and videos. In my opinion, the ARP website is one of the most informative resources for details regarding cooling unit failures. In the unlikely event you can’t find what you are looking for, you can use the “Contact Us” link, and Paul or Mao will be happy to respond.
If you are interested in going the extra mile to protect your RV and your family, check out the Fridge Defend by ARP system at arprv.com. Combining an ARP system with other fire suppression systems in vulnerable areas of your RV can bring much-needed peace of mind.
Send your troubleshooting questions to Steve Froese at techtalk@fmca.com. The volume of correspondence may preclude personal replies. Not all responses will apply in every instance. Some situations may require a visual inspection and hands-on testing. If you choose to follow any procedures outlined in this column, first satisfy yourself that neither personal nor product safety will be jeopardized. If you feel uncomfortable about a procedure, stop and make an appointment with an RV service facility.
You may also want to consult the FMCA Forums (https://community.fmca.com) to see whether your question has already been addressed or, if not, to post it.