Randyretired Posted March 3, 2016 Report Share Posted March 3, 2016 A recent topic on the ARP Refigerator Control convinced me to buy one. Now installed I have a way to measure the temperature and I have been wondering what is the optimum temperature. Our refrigerator has 3 fans that are activated by temperature but when the sun is shining and the outside temperatures are in the upper 80's the fans seem to run constantly during cooling. The ARP indicates a temperature of around 169. Is that good or would another fan help? Is there an optimum temperature? Randy 2001 Volvo VNL 42 Cummins ISX Autoshift Link to comment Share on other sites More sharing options...
Kirk W Posted March 3, 2016 Report Share Posted March 3, 2016 I think that the answer is probably different for different models of refrigerator. Our compact model is using an ARP that includes the fan control and the fan does operate pretty constantly in hot weather. Good travelin !...............KirkFull-time 11+ years...... Now seasonal travelers.Kirk & Pam's Great RV Adventure Link to comment Share on other sites More sharing options...
dewilso Posted March 3, 2016 Report Share Posted March 3, 2016 I'd think ARP would know? Dave W. KE5GOH Stuck in the 70's --- In E. Texas Link to comment Share on other sites More sharing options...
ARPrvSafe Posted March 3, 2016 Report Share Posted March 3, 2016 Hi Randy, I am pleased to answer your questions, I will answer them inline below: Q1) what is the optimum temperature? A1) As Kirk stated, the temperature in the boiler of the fridge should be fairly constant. The boiler temperature will only change by a few degrees as the ambient temperatures change. Q2) Our refrigerator has 3 fans that are activated by temperature but when the sun is shining and the outside temperatures are in the upper 80's the fans seem to run constantly during cooling. A2) We were in Yuma yesterday at 90F, no wind, and the sun shining on the fridge. Our fridge (Dometic RM3663) ran all day, the 1 fan ran all day also, the fridge stayed at 38F and the freezer at 4F . When the sun set the ambient temperature dropped into the 80s and the fans started cycling. Our fan setting is on setting 4, please see bottom of following webpage for fan adjustment: https://www.arprv.com/rv-fan-vent.php Q3) The ARP indicates a temperature of around 169. Is that good or would another fan help? A3) The boiler temperature is a function of the pressure in the cooling unit, the location of the sensor, and some other factors. Without knowing the make of your fridge (one of the factors I would say that your boiler temperature is very good and reflects a healthy cooling unit. As stated above in A1, increasing the number of fans will not change the boiler temperature, to add to the above comment, the boiler is insulated and thus is fairly unchanged by high ambient temperatures. ARPrvSafe Question) Our question is pointing away from the ARP Control boiler temperature and more to the fridge performance, did the temperatures in the fridge stay at acceptable values? What type of fridge are we talking about? We did data log our fridge yesterday, not sure if anyone wants to see the boiler temperature curve? Let us know if there is interest in our uploading it? Link to comment Share on other sites More sharing options...
Randyretired Posted March 3, 2016 Author Report Share Posted March 3, 2016 ARPrvSafe, Thank you for the response. The refrigerator is a Dometic RM1350. I replaced the cooling unit a couple of years ago as the original failed after 3 years. On the original cooling unit the 2 factory fans ran nearly continously and I suspect that may have contributed to the early demise. I added an air deflector recommended by the cooling unit manufacturer and a 3rd fan when the new cooling unit was installed. The refrigerator temperature nearly always is 36 now so that is not a problem. Our fans are using the controll recommended by the cooling unit manufacturer and during cooler wheather as the fans cycle the boiler temperatures vary between 155 and 160. Later in the day when the temperature was in the upper 80's the boiler temperature was at 169 and the fans ran continually. Since fans are cheap and easy to add I was just wondering if I should add another. Randy 2001 Volvo VNL 42 Cummins ISX Autoshift Link to comment Share on other sites More sharing options...
ARPrvSafe Posted March 3, 2016 Report Share Posted March 3, 2016 ARPrvSafe, Thank you for the response. The refrigerator is a Dometic RM1350. I replaced the cooling unit a couple of years ago as the original failed after 3 years. On the original cooling unit the 2 factory fans ran nearly continously and I suspect that may have contributed to the early demise. I added an air deflector recommended by the cooling unit manufacturer and a 3rd fan when the new cooling unit was installed. The refrigerator temperature nearly always is 36 now so that is not a problem. Our fans are using the controll recommended by the cooling unit manufacturer and during cooler wheather as the fans cycle the boiler temperatures vary between 155 and 160. Later in the day when the temperature was in the upper 80's the boiler temperature was at 169 and the fans ran continually. Since fans are cheap and easy to add I was just wondering if I should add another. Hi Randy, Thanks for your informative response. Some of the present fan controls do not control the fans very well, I assume you are not using an ARP fan control? Fans running continuously can be from one of two issues: 1) You have a side-vent application and the fans need to be run continuously to help the cooling unit vent. 2) You have one of the cooling units where the snap-switch that controls the fans is mounted above the flue tube, thus when run on LP gas the fans always run. The temperature swing is very large for your boiler being from 155-170. If the fans are directly affecting the boiler temperature I would guess that the ARP temperature sensor is not in the correct spot? Or, more likely you are reading the boiler temperature when the cooling unit is not at steady-state boiler temperature. You can tell if you are at steady-state by reading the temperature about an hour after the heat source turns on. WHen the heat source turns on or off the temperature either raises or lowers, I wonder if you are reading during the startup or turn off period? 170 steady-state is what I would expect to see from your fridge. I am more concerned about where your fans are mounted rather than the quantity of fans. Did you go to our website and look at how we suggest to mount the fans, or in the case of the ARP fan control the blowers? A single blower mounted at the bottom and top is all you should need. Link to comment Share on other sites More sharing options...
Randyretired Posted March 3, 2016 Author Report Share Posted March 3, 2016 We are in Bullhead City and the outside temperature is 80. The refrigerator is in a slideout and the unit has been cooling for a while. The boiler temperature is 167. Also the refrigerator is on the West side so it is currently in the shade and the fans are cycling. The sensor is mounted about even with the 3rd coil as shown in fig. 3b sensor location 2. That was where I could reasonably reach without removing the refrigerator. The refrigerator is on electric and we have not tried gas yet since the ARP install. Two of the fans are in the factory location, moumted side by side about mid way on the refeigerator. The 3rd fan is on top. Randy 2001 Volvo VNL 42 Cummins ISX Autoshift Link to comment Share on other sites More sharing options...
ARPrvSafe Posted March 3, 2016 Report Share Posted March 3, 2016 The issue with the fans in the middle of the two side-vents is that they have a tendency to recirculate the air inside the cooling unit compartment. I would suggest installing a fan so that is positioned as shown on our website. Mount a fan or better yet a blower on the lower vent so it is sucking in cool air from outside. Putting the blower on the bottom is best because it is easier to move/pump cool air. Also, the cool air being brought into the cooling unit compartment will force the hot air up by natural convection. So yes, another fan/blower at the bottom is a good idea. Link to comment Share on other sites More sharing options...
Randyretired Posted March 3, 2016 Author Report Share Posted March 3, 2016 ARPrvSafe, Thank you, I will add another fan to the bottom. I put the refrigerator on gas after the last post and the boiler temperature is now 173. The outside temperature is 82 now. Randy 2001 Volvo VNL 42 Cummins ISX Autoshift Link to comment Share on other sites More sharing options...
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