pianotuna
Regina, SK, Canada
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Joined: 12/18/2004
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Hi Chris,
I can't give you an exact temperature--but I can say that in the winter time my thermo cube turns on at 35 f and off at 45 f.
https://www.amazon.ca/Farm-Innovators-TC........hermostatically-Controlled/dp/B0006U2HD2
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.
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Cummins12V98
on the road
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Joined: 06/03/2012
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My last DRV had the frig in the slide with the two vents on the slide outer wall. I cleared out all the loose insulation so it had a clear path from lower to upper areas. I then added a small computer 12V fan to the back side of the upper vent. I placed it on a 12V switch. The temp drop in the frig was remarkable!!!
2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's
37,800# GCVWR "Towing Beast"
"HeavyWeight" B&W RVK3600
2016 MobileSuites 39TKSB3 highly "Elited" In the stable
2007.5 Mobile Suites 36 SB3 29,000# Combined SOLD
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SJ-Chris
San Jose, Ca
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Joined: 09/24/2017
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Finally got around to adding some fans behind one of my Class C RV's refrigerators to try it out.
Two of these fans....
https://www.amazon.com/gp/product/B08FBP2ZM5
0.25amp, 15CFM, 32.8 dBA (Each)
$9 each
One of these thermostats....
https://www.amazon.com/gp/product/B0B2WTPJ3G
~$4
~$3 worth of other wire, zip-ties, etc.
$9 + $9 + $4 + $3 = $25 modification
Tested this on back to back days that had identical daytime high 90 degree temps.
Started with the refrigerator on for 24hrs prior to starting the test. Only opened the doors to check the temp after they had been closed for 24hrs.
With the fans OFF, at 3pm in the peak of the afternoon heat, the freezer was 11 degrees F and the refrigerator was 43 degrees F. (warmer than I would like)
With the fans ON (the next day), at 3pm in the peak of the afternoon heat, the freezer was 6 degrees F and the refrigerator was 37 degrees F.
Result: 6 degrees cooler with the fans on (thermostatically controlled) behind the refrigerator.
I consider it a win. I plan on adding one more fan (...might help another 1-2 degrees) and cleaning up the wires a bit. Will probably add to one of my other RVs that has a fridge that runs at about 40 degrees F during the heat of the day.
![[image]](https://i.imgur.com/xPqGcRFl.jpg)
One last thing for me to figure out....I'm sure someone here can assist...
Currently, I am tapping 12v power off some easy to access wires (the orange and white wires coming from the right side of the photo). I thought they would only be hot (have power) when the refrigerator was on. I was wrong though...they are always hot/on.
Can someone tell me which of these wires is ONLY hot/12v when the fridge is turned on inside the RV? Is it the red wire that I marked with the yellow "A"?
![[image]](https://i.imgur.com/mX6y82nl.jpg)
Thanks!
-Chris
San Jose, CA
Own two 2015 Thor Majestic 28a Class C RVs
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enblethen
Moses Lake, WA
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Joined: 01/05/2005
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I would not tap any wires. Power the fans up off the 12-volt Red and Black. Install a manual switch or route through small thermostat.
Bud
USAF Retired
Pace Arrow
2003 Chev Ice Road Tracker
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SJ-Chris
San Jose, Ca
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enblethen wrote:I would not tap any wires. Power the fans up off the 12-volt Red and Black. Install a manual switch or route through small thermostat.
It is running through a thermostat. But as currently wired, the thermostat always has power, and if the temps rise enough (even if the refrigerator isn't on), the fans will go on....even if the RV is in storage. Yes, I can open the side panel and disconnect the power to the thermostat (...I have easy connectors on the power lines to the thermostat), but I'd rather just have it wired to the "Fridge on/off" power so that it will never be on if the fridge is not on.
-Chris
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bucky
Raleigh metro
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Joined: 05/07/2003
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This issue needs two different discussions.
Roof vent
Side vent
Roof vent systems vent themselves.
Side vent systems normally found in slides need help which is shy those systems have fans as they don't self vent as well as reef vent designs.
Puma 30RKSS
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fyrflie
Martinez, CA. USA
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Joined: 07/31/2003
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One thing I found this winter , when I replaced my frig cooling unit, was that the area above the fridge was not blocked off from the backside ventilation area. So any heat generated by the frig would rise up and fill that void, then eventually push into the coach.
Before I slid my fridge back in, I installed a piece of sheet metal to block off that void area and keep the heat rising up and out the roof vent.
My thought is that the efficiency of the refer depends largely on the removal of heat from around the cooling unit, so any effort made to assist that process can only help.
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SJ-Chris
San Jose, Ca
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bucky wrote:
Roof vent systems vent themselves.
Side vent systems normally found in slides need help which is shy those systems have fans as they don't self vent as well as reef vent designs.
While it is true roof vent systems vent themselves (via the fact that hot air naturally rises), assisting this airflow (ie. adding fans) helps the process and appears to make the cooling happen faster, colder, and also using less propane when not hooked up to electric. My motivation was 99% just trying to make my fridge/freezer a little colder. With the 2 fans I added, the fridge/freezer is running 6 degrees F colder. For a $25 modification, I consider that a success/worthwhile.
I don't have a side vent system (found in slides), but it is easy to understand that naturally they will not vent as well since they don't have a roof vent. For those designs assist fans would appear to be even more helpful (or necessary).
Obviously, if someone is happy with their fridge/freezer temps then no modification is necessary.
Stay cool!
Chris
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hotjag1
Lake Chelan, Wa/Lake Havasu, Az.
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Joined: 07/14/2002
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I wired a 4" 12v fan in the back of the refers on both of our motorhomes. The Allegro has side vents and the Isata has a roof vent. The fans made a difference on both RV's keeping the refers in the high 30's to 40 degrees on 90plus degree days. I turn them on manually with a switch when needed.
* This post was
edited 08/13/23 04:42pm by hotjag1 *
hotjag1
2003 40' Allegro Bus, 3 slides, 400hp 8.9 liter ISL Cummins
2000 24' Dynamax Isata
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SJ-Chris
San Jose, Ca
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Added a 3rd fan and repositioned a few things. Cleaned up the wiring. I'll be taking it out in a week and we'll see how it does. This next trip will only be in ~80 degree weather, so I don't know if the fans will come on often and/or be of much help. The real test will be the next time I am boondocking in 95F+ temps.
![[image]](https://i.imgur.com/p6CH92al.jpg)
These 3 fans will move 15cfm x 3 = 45cfm in theory. Running a test right now in ~94F temps while in storage.
-Chris
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