Hi John. Good post.
JBarca wrote:
Chris, I have been following your post.
I did review the ARP system a while back, just never made it to installing any, yet. I called and talked with them today. They are very down to earth, and they are a, know what they are doing company.
I have visited the ARP site and seen many many posts from the makers of Fridge Defend on some online forums. It seems like they have a good product AND they seem to be genuinely passionate about safety. Very knowledgeable. Seem like nice people. Seems like they want to help people.
JBarca wrote:
I am going with the Fridge Defend V5.11 with the fan control. I want to add the defrost fans inside the fridge and to cycle them you need the fan control version. The V5.11 has an alarm, so you know when you have a problem and you and tweak the settings as needed. Since most all the fridges I work on are older, there may be some level of coolant damage from prior owners, so the fridge may have limited life, but having the fire safety part is a big plus.
If you are looking for an integrated system that controls the boiler temp, the fan(s) behind the refrigerator, and fans inside the refrigerator, then the Fridge Defend is definitely for you.
I'm not anti-Fridge Defend...I think they have a great product. But I'm a DIYer and I enjoy tinkering with modifications. I personally believe that from a safety standpoint, the most important thing on these absorption refrigerators is to keep the boiler under 220*C. I believe a simple high temp thermostat can easily accomplish this task, and they only cost $20. If I only had 1 RV I would probably still just buy a Fridge Defend. But I've got 3 RVs. So if I can implement this DIY fix it will save me 3x the money.
JBarca wrote:
Since I already have a fan up on the roof vent and a thermal disk switch to turn it on and off, I may switch the roof vent fan to the Fridge Defend. You just parallel the inside defrost fans with the roof vent fans. The ARP fan relay is rated at 20 amps, plenty for the milli amp fans I use, and the ARP defrost fans.
I'm not sure why you would want to tie your roof vent fan to your inside defrost fans. They aren't related in function. The Fridge Defend has a feature to control fan(s) that are placed behind the refrigerator to provide extra cooling to the coils behind the fridge and it seems like you'd want to use these controls for your vent fan.
(Side note: I'm also planning a DIY modification for putting fans behind the refrigerator controlled by a separate thermostat.)
JBarca wrote:
Another reason for the Fridge Defend not yet mentioned is cold weather. I know you may not camp in cold down to freezing, and below, but in our area, freezing temps are here and we do winter camp.
If you want to get close to 32F outside or go below, the fridge as it stands in the stock configuration will slow down and may stop working. The heating may not stop, but the fluid can slow down flowing from what I have read. It seems Dometic does offer a lower vent hood that has some blocked off vents to lower the amount of cold air entering.
This Dometic lower vent is made for cold weather, just they do not list much else or fit the older Dometic vent frames. Norcold sells a cold weather kit to heat up a certain return tube on the cooling coil. Here is one of them. https://www.amazon.com/Norcold-634913-Cold-Weather-Kit/dp/B00T36VI30
I have not been able to find Dometic offering that heat strip. By using the heat strip on the Norcold and helping to reduce the cold air intake, it is reported you can go down to 0F. Some folks use an incandescent light bulb in the outside compartment.
The ARP system will help to shut off the boiler heat if the coolant stops flowing due to the cold weather for any reason.
Doug may be able to add some more to this and if he knows if Dometic offers a cold weather kit or do you just use the Norcold one? Most all of the older campers I restore have RM2652 fridges that I service.
Thanks
John
I will admit, I had not thought about ultra cold weather usage. I have been camping down to ~30*F and didn't have any issues with the refrigerator/freezer temps. I don't have immediate plans to camp down to 0*F. I'm guessing that the boiler getting hot to the touch does a fair job heating the cavity/space behind the refrigerator. But I can see how if it were 0*F outside and that cool air is being pulled in then maybe it could affect the cooling unit functionality. If I was going to camp in such temps I think I would consider putting something along the back side of the rear vent to limit the amount of air that could enter. That seems like it would allow the heat of the boiler to keep the air behind the refrigerator warm enough for proper operation. Not sure if that is true or not, but I'd start there.
I am big on safety. I do think it is important for safety and also to help protect your cooling unit from overheating damage to have some sort of high temp thermostat (either DIY or Fridge Defend) on your boiler to keep it below 220*C (428*F).
-Chris
