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Author Topic: Rv fridge exhaust fan question  (Read 481 times)

GARYJ

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Rv fridge exhaust fan question
« on: October 28, 2019, 11:04:26 PM »
Mine is a 2007 Mallard travel trailer with a two door dometic fridge
Itís working just fine but Iíve been watching many YouTube videos about installing an exhaust fan to help discarding warm air and helping itís performance
Does it really work? Is it really worth the effort?
Thanks for your advices

Lou Schneider

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Re: Rv fridge exhaust fan question
« Reply #1 on: October 29, 2019, 12:05:50 AM »
Usually external fans only make a difference in high temperatures, above about 90 or 100 degrees unless there's another factor limiting the airflow over the refrigerator's rear coils.

The way the system is supposed to work is the hot tubing on the rear of the refrigerator sets up a chimney effect and convection carries waste heat out of the roof vent while sucking in cooler air from the bottom vent.

When the ambient air temperature is high enough, there's no longer enough temperature difference between the outside air and the hot tubing to maintain the convection flow.  The chimney effect breaks down and heat is no longer carried away from the cooling unit.  This is where a small fan blowing upward behind the refrigerator can help, restoring the airflow to carry the heat away from the refrigerator.
« Last Edit: October 29, 2019, 12:14:33 AM by Lou Schneider »

John From Detroit

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Re: Rv fridge exhaust fan question
« Reply #2 on: October 29, 2019, 06:32:59 AM »
When replacing my 14+ cooling unit that faild (I put fans on it oh about 12 years ago) my RV tech showed me the downside of those fans.

Have you ever notice how fans tend to get crudded up. Same for air conditioner condensers.. Same for the heat exchanger when you have fans blowing on it.....

I may again put fans on but now I know how to clean the heat exchanger

(The crud blocks or reduces air flow)
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lynnmor

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Re: Rv fridge exhaust fan question
« Reply #3 on: October 29, 2019, 09:43:42 AM »
Usually a fan is required if the fridge is installed in a slide and the vents exhaust thru the side.  The chimney effect is poor unless the air exhausts thru the roof.

Gary RV_Wizard

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Re: Rv fridge exhaust fan question
« Reply #4 on: October 29, 2019, 04:54:06 PM »
If the fridge is cooling fine in the places & temperatures you normally travel, I wouldn't install a fan. As others have explained, they are useful when the rear of the fridge area does not have adequate normal convection ventilation and thereby struggles to cool.  You stated you don't have that problem, so there is nothing to be gained.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

mudisfun

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Re: Rv fridge exhaust fan question
« Reply #5 on: October 31, 2019, 12:33:32 PM »
I placed two 5 inch fans at the top of the chimney to help with air flow over the fins... just two 5 inch computer fans which have a 95 degree F normally open bi-metal thermostat inline. When the temp in the chimney reaches 95F, the fans kick on increasing air flow and helping dissipate heat. When the interior temp drops, they kick off until needed again.

Total amp draw is something like .75 between the two.

Gary RV_Wizard

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Re: Rv fridge exhaust fan question
« Reply #6 on: October 31, 2019, 03:34:28 PM »
I doubt if that 95 degree thermostat ever opens while the fridge is on - the flue temperatures will probably always be 100+.   For example, Norcold fridges that have factory-installed fans switch on at 135 and off again when it drops to 115.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL