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01-08-2013, 10:44 AM
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#1
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Senior Member
Trailer: 1983 13 ft Scamp
Posts: 3,082
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Thermostatically controlled refrigerator vent fan
What thermostatically controlled switch should I get to turn on a fan on the back of the frig to keep coils cool?
Turn fan on at
80 degrees ?
85 degrees ?
90 degrees ?
95 degrees ?
100 degrees ?
Should it be a normally open switch or a normally closed thermostat temperature switch?
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01-08-2013, 10:52 AM
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#2
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Senior Member
Name: Steve
Trailer: 2018, 21ft escape— 2019 Ram 1500 Laramie
NW Wisconsin
Posts: 4,500
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Switch
Normally open "Closes on Temperature Rise"
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01-08-2013, 11:00 AM
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#3
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Senior Member
Trailer: Trillium 2010
Posts: 5,185
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You're ahead of me. When needed I hang mine on the outside with a couple of paper clips and attach it to the battery with alligator clips. Raz
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01-08-2013, 11:47 AM
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#4
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Senior Member
Trailer: No Trailer Yet
Posts: 5,112
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It seems like it would make more sense to put the thermostat inside the fridge and have it kick on at 40 degrees F.
You might even be able to liberate one from a discarded refrigerator on the curb.
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01-08-2013, 12:19 PM
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#5
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Senior Member
Trailer: 1983 13 ft Scamp
Posts: 3,082
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Adding a fan on the inside of the frig. that kicks on a 40 degrees.
Adding a fan on the outside of the frig. fins that kicks on a ______ degrees?
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01-08-2013, 12:34 PM
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#6
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Senior Member
Name: Dave W
Trailer: Trillium 4500 - 1976, 1978, 1979, 1300 - 1977, and a 1973
Alberta
Posts: 6,926
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I am assuming that you want the fan to come on only when the fridge is cooling. Why would you want it otherwise?
I guess it depends on where you put the sensor. The top horizontal pipe, just after the chimney gets the hottest. It is almost too hot to touch, so I would use the 100°F, (or higher) sensor on the cool end of that. That way when the fridge is off, so is the fan. To determine the correct temperature for the sensor, I would run the fridge on 12VDC, or 120VDC, (likely the coolest it will run). Then measure the temperature at the point that you want to mount the sensor.
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01-08-2013, 12:56 PM
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#7
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Senior Member
Trailer: No Trailer Yet
Posts: 5,112
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Quote:
Originally Posted by Kevin K
Adding a fan on the inside of the frig. that kicks on a 40 degrees.
Adding a fan on the outside of the frig. fins that kicks on a ______ degrees?
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I'm assuming that you want the fan to run when the fridge can't maintain 40 degrees inside without assistance from the fan. Ideally you'd monitor the inside temperature, as that is what you really care about.
I guess a second best way would be to monitor the ambient temperature inside the vented enclosure and have it kick the fan on at 80* F or so. I'd put the sensor below the heat exchanger so it measures incoming air temperature.
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01-08-2013, 12:59 PM
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#8
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Moderator
Trailer: 2009 19 ft Escape / 2009 Honda Pilot
Posts: 6,221
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Quote:
Originally Posted by Thomas G.
It seems like it would make more sense to put the thermostat inside the fridge and have it kick on at 40 degrees F.
You might even be able to liberate one from a discarded refrigerator on the curb.
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The fan inside the fridge should run full time, as its chore is to circulate the air, resulting in an even temperature inside, regardless of temperature.
For the venting fan, it could be a thermostatically controlled one, or if it was me, I might be inclined to just have it on a switch for when I wanted it on.
__________________
2017 Escape 5.0 TA
2015 Ford F150 Lariat 3.5L EcoBoost
2009 Escape 19 (previous)
“Most folks are about as happy as they make up their minds to be.” — Abraham Lincoln
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01-08-2013, 01:14 PM
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#9
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Senior Member
Trailer: 92 16 ft Scamp
Posts: 11,756
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I am with Jim, my fridges performance can vary depending on whether it is running on propane or electrical & whether or not there is any breeze outside or not. I would be inclined to think a manual on and off switch would be better than an auto system based on outside temp - why drain battery power if you dont need to. A switch located inside the trailer with a light on it as a remember the fan is on would be a good thing - I know I have forgotten on more than one occasion to turn my outside fridge fan off. ;-)
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01-08-2013, 01:16 PM
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#10
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Senior Member
Name: Jon
Trailer: Escape 21C
New York
Posts: 2,387
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Quote:
Originally Posted by Jim Bennett
The fan inside the fridge should run full time, as its chore is to circulate the air, resulting in an even temperature inside, regardless of temperature.
For the venting fan, it could be a thermostatically controlled one, or if it was me, I might be inclined to just have it on a switch for when I wanted it on.
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2X. I've got mine on a switch - lets me shut it off if I want quiet.
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01-08-2013, 01:29 PM
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#11
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Senior Member
Trailer: No Trailer Yet
Posts: 5,112
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I've got my interior and exterior fans on a switch, too, but the OP's question was about how to thermostatically control the fan.
I still think that it makes sense to control the external fan based on internal temperature. If it is 40 degrees or below inside, you don't need the fan. If it is above, the fan can help to bring the temperature down.
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01-08-2013, 02:12 PM
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#12
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Senior Member
Trailer: Boler (B1700RGH) 1979
Posts: 5,002
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How about double throw center off switch: one way to power the fan regardless of any temperature (manual on), the other way to power the fan through the thermostatic switch (auto), and center position off (manual off)?
In this case, I would want the fan when the refrigerator needed help, so I would locate the switch at the top of the coils but away from the burner exhaust, and choose a temperature above that observed for a running refrigerator in cool ambient conditions, but below that observed when the refrigerator is running continuously to keep up.
I understand Tom's point: if it can keep up without assistance, there's no need to run the fan.
__________________
1979 Boler B1700RGH, pulled by 2004 Toyota Sienna LE 2WD
Information is good. Lack of information is not so good, but misinformation is much worse. Check facts, and apply common sense liberally.
STATUS: No longer active in forum.
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01-08-2013, 03:08 PM
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#13
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Moderator
Trailer: 2009 19 ft Escape / 2009 Honda Pilot
Posts: 6,221
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Quote:
Originally Posted by Brian B-P
I understand Tom's point: if it can keep up without assistance, there's no need to run the fan.
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Unless you are using propane, often the increased circulation will allow you to use a lower temperature setting due to the efficiency it introduces, thus saving fuel. If you are on electric, and can keep the temps in the fridge low enough, any extra energy cost due to a higher setting is on the campgrounds dime.
All this is dependent upon how well the existing fridge in your trailer is vented. I have yet to have trouble keeping things cold in temps well above 30°C, though I have heard of others having troubles with the same trailer.
__________________
2017 Escape 5.0 TA
2015 Ford F150 Lariat 3.5L EcoBoost
2009 Escape 19 (previous)
“Most folks are about as happy as they make up their minds to be.” — Abraham Lincoln
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01-08-2013, 04:43 PM
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#14
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Senior Member
Name: Steve
Trailer: Scamp 13
California
Posts: 1,890
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In my case my intent is to use the muffin fan with a manual switch and a thermal switch as back-up for my failure to operate properly.
I have purchased from Senasys ( senasys.com ) an airstream mount Thermal Switch part # 2511F002 switch 070 F-563 Close 70 degree F, Open 60 degree F
$9.75 with shipping close to 15 bucks
This switch will turn on the fan at 70 degrees F and turn it off if it reaches 60 degree F ambiant air temperature.
With my desert camping I can easily see 50 degree temperature swings in a single day especialy in the spring and fall. I will run the wiring from power to a manual switch then to the thermal switch sitting in ambiant air in the lower outside refrigerator compartment and then to the fan. Camping in the desert the fan will be needed most of the time anyway but late in the night the thermal switch will turn off the fan so I dont have to, and prevent over cooling and to conserve battery. Much more reliable than me doing it.
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01-08-2013, 10:07 PM
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#15
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Member
Name: Sam
Trailer: Owner 16' Amerigo
Tennessee
Posts: 79
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I have a 3 way also and I have build duct work over my coils with two 12 volt fans. The duct work has insulation on the outside and will have the ducting vented to the outside, and I have not decide if the input air should be cabin or outside. I'll have to play with that. The exhaust will be insulated and of course vented over board. After reading posts of others I plan on an inside fan to move the air around, but I will have a remote thermometer inside, so I make sure I have refrigerator running right. I also plan on an extra layer of insulation around my Refrigerator. With all the complains about warm refrigerators I am taking the extra steps to make mine work as good as possible. Could be over kill, but I am leaning on the very safe side.
Sam
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01-09-2013, 10:26 AM
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#16
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Senior Member
Trailer: 1983 13 ft Scamp
Posts: 3,082
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Sounds like the best way to go is with a switch for the fan inside the frig. and a switch for the fan on the outside fins of the frig. I will use. 2 of these LED light switch's.
I will place the switch's in the upper left of my microwave cabinet.
Thanks for all the tips.
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01-09-2013, 01:10 PM
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#17
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Senior Member
Trailer: Trillium 2010
Posts: 5,185
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Check the refrigerator installation manual for baffle information. Depending on how far apart the intake vent and exhaust vent are, the manufacture may recommend adding baffles to direct the air flow and increase the draft. Like a chimney. Basically by adding baffles you can direct the air flow such that it better removes the heat. Adding a fan is good. Adding a fan and baffles is better. Casita may already have put them in. They are easy to spot with a mirror. Raz
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