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04-17-2021, 09:22 PM
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#1
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Is cool
Join Date: May 2019
Posts: 18
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Refrigerator Vent Fans
I've read a ton of threads on the subject, but haven't seen anybody that's sealed the vent to the fans. We're in Texas and it's always warm if not hot and/or humid, and have had our micro lite out 6x's and fridge has barely cut it, except on our 1 trip when it was cold outside. My thought is to seal the fans to the roof vent to create a vacuum, instead of just improving the natural convection. Roughing for at the least the foreseeable future is no sewer, so power running them is not an issue. Wasn't sure if there could be too much ventilation.
Measured today and the vent opening is 20.5"x6.5", I found this nice ready plate that would fit in there great, and I was thinking of sealing the fans to the top of the he vent with some foam gasket. Then the fans have a more open design vs some of the ones with spiral blades. Fans are rated at 50cfm (2 of these) and 100 cfm (one of these). Was gonna switch each individually, which would give us 50-200cfm in 50cfm increments.
Does anybody know if there can be too much airflow? Since the refrigerators operation seems pretty dependant on airflow over condenser, I'm not seeing any obvious downsides.
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04-18-2021, 10:32 AM
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#2
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Senior Member
Join Date: Jul 2017
Location: North of Seattle, WA
Posts: 17,263
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I haven't camped in Texas lately but I have camped on the East side of my state in 100 degree plus temps and found my refrigerator struggled.
I cured this by installing a Titan fan system on the roof end of my refer's vent stack.
Removed vent cover and secured the two 120 mm fans on top of the "bug screen" with them blowing up and out. The Titan fans have a controller that monitors the temp in the vent stack and if set on Auto will switch on when temp hits a preset threshold and as it increases the controller speeds the fans through several steps from Slow to max.
Power consumption is only around 1/2 amp so it's great when off grid.
Fans are nice and quiet, waterproof, and fit the vent stack perfectly. Controller fits nicely just above my refrigerator inside and can also be controlled manually if desired.
They can also be installed on the intake vent at the bottom of the vent stack, just make sure air flow is IN on that end.
To finish the project I also installed two 90 mm computer fans inside the refer directly on the "fins" that produce the cold in the refer. A DPDT switch wired so I had Off-1 ON-2 ON allows me to use only as much fan as needed to maintain 35 degrees in the refer. A couple pieces of aluminum angle, some 12 gauge bare copper wire and four electrical box ground clips made a great support, just using the ground clips to secure the wire to the fins, forming a loop at the other end, and screwing the loop to the angle brackets holding the fans was all I needed to mount the fans.
It really takes two fan setups to get the most out of the refrigerator. Cooling the back where evaporator and condenser are is important but getting the cool air distributed in the refer helps the system generate more "cool" both in the refer but in the freezer as well.
In my setup I find that leaving the Titan Fans on Auto, and a single fan running in the refer keeps my freezer down near zero and the refer interior at 35 degrees, all while only drawing less than .5 amp from the batteries. At night the Titan Fans turn off and the computer fan inside the refer only draws .25 amp while running by itself. Easy on the batteries.
You really can't have too much air flow but battery current draw when not plugged in can be an issue which is the beauty of the Titan system. The controller operates the fans only when needed, and in the amount of air flow that's needed.
Even if one doesn't boondock it's not a bad idea to "build" as if you were doing it all the time. Then you're covered during power outages, rest stops along the way when traveling, as well as just turning off fans when not needed to avoid unnecessary wear.
__________________
"A wise man can change his mind. A fool never will." (Japanese Proverb)
"You only grow old when you run out of new things to do"
2018 Flagstaff Micro Lite 25BDS
2023 f-150 SCREW XLT 3.5 Ecoboost (The result of a $68,000 oil change )
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04-18-2021, 10:41 AM
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#3
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Senior Member
Join Date: Jan 2016
Location: x
Posts: 12,423
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I would not seal off the chimney stack. TM install is impressive I went with large computer case fans controlled by snap disks to control starting the fans and stopping the fans that are mounted at the top of the chimney. I also installed to smaller computer fans on the inside of the Frig against the fins that run when the frig is on. My system has worked great in the hottest weather on gas or elect.
__________________
Retired Navy
Jake my sidekick (yellow Lab) 10/04 - 05/20
2017 RAM 2500 CC 4X4 Cummins Diesel
2016 Flagstaff 26 FKWS
AF&AM & El Korah Shrine of Idaho
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04-18-2021, 01:11 PM
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#4
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Senior Member
Join Date: Jul 2017
Location: North of Seattle, WA
Posts: 17,263
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Quote:
Originally Posted by SeaDog
I would not seal off the chimney stack. TM install is impressive I went with large computer case fans controlled by snap disks to control starting the fans and stopping the fans that are mounted at the top of the chimney. I also installed to smaller computer fans on the inside of the Frig against the fins that run when the frig is on. My system has worked great in the hottest weather on gas or elect.
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I agree, don't seal the stack. I left the area ac round the fans open so when they were off, normal convection was unimpeded.
__________________
"A wise man can change his mind. A fool never will." (Japanese Proverb)
"You only grow old when you run out of new things to do"
2018 Flagstaff Micro Lite 25BDS
2023 f-150 SCREW XLT 3.5 Ecoboost (The result of a $68,000 oil change )
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04-18-2021, 05:06 PM
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#5
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Is cool
Join Date: May 2019
Posts: 18
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I'll probably end up mounting, just on top of the vents, so it's close to the screen but not blocking.
I did purchase this and it has helped with the to swings from opening/closing.
https://rvcoolingunit.com/Dometic-3-...-P5661663.aspx
Thanks for input!
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04-18-2021, 07:49 PM
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#6
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Senior Member
Join Date: Jul 2017
Location: North of Seattle, WA
Posts: 17,263
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Quote:
Originally Posted by ChawlzW
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Nice fan setup.
They do work.
__________________
"A wise man can change his mind. A fool never will." (Japanese Proverb)
"You only grow old when you run out of new things to do"
2018 Flagstaff Micro Lite 25BDS
2023 f-150 SCREW XLT 3.5 Ecoboost (The result of a $68,000 oil change )
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04-18-2021, 09:34 PM
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#7
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Senior Member
Join Date: Jun 2011
Location: Big brown desert
Posts: 3,003
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I went with 2 120mm fans at the top of the chimney sucking out. I removed the screen and put them on the inside and made a new screen that was removable. I also put another fan at the bottom bringing in air. All 3 are hot all the time and last weekend the fridge was at 32 and freezer at -4. I do have the smaller fans inside blowing on the fins but I am needing to replace one from wearing out.
__________________
2014 Stealth Evo 2850- "Woodstock"
2011 Toyota Tundra Rock Crawler TRD 5.7- "Clifford"
2013 Honda Accord Coupe V6 w/Track Pack- "Julia"
Just glad to get away
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04-19-2021, 08:05 AM
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#8
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Senior Member
Join Date: May 2019
Posts: 1,013
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04-19-2021, 11:58 AM
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#9
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Senior Member
Join Date: Dec 2017
Location: Saint George, UT
Posts: 116
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This is an exhaust setup I made using two computer fans on Isata3. Held up by magnets, remove before leaving campsite.
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04-19-2021, 09:05 PM
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#10
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Is cool
Join Date: May 2019
Posts: 18
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Quote:
Originally Posted by 01tundra
I made my own steel mounting plate, used foam tape to seal the mounting plate to the plastic vent curb. Also used gaskets to seal the fans to the plate.
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How does it perform? Has having it sealed caused any problems? Too much airflow?
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04-20-2021, 07:05 AM
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#11
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Senior Member
Join Date: May 2019
Posts: 1,013
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Quote:
Originally Posted by ChawlzW
How does it perform? Has having it sealed caused any problems? Too much airflow?
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Works great for us, there's no such thing as too much airflow in TN.
Ours operate off of evaporator temperature so they only run when they need to based on my temperature set point.
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04-20-2021, 08:24 PM
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#12
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Senior Member
Join Date: Mar 2015
Posts: 822
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Quote:
Originally Posted by TitanMike
I haven't camped in Texas lately but I have camped on the East side of my state in 100 degree plus temps and found my refrigerator struggled.
I cured this by installing a Titan fan system on the roof end of my refer's vent stack.
Removed vent cover and secured the two 120 mm fans on top of the "bug screen" with them blowing up and out. The Titan fans have a controller that monitors the temp in the vent stack and if set on Auto will switch on when temp hits a preset threshold and as it increases the controller speeds the fans through several steps from Slow to max.
Power consumption is only around 1/2 amp so it's great when off grid.
Fans are nice and quiet, waterproof, and fit the vent stack perfectly. Controller fits nicely just above my refrigerator inside and can also be controlled manually if desired.
They can also be installed on the intake vent at the bottom of the vent stack, just make sure air flow is IN on that end.
To finish the project I also installed two 90 mm computer fans inside the refer directly on the "fins" that produce the cold in the refer. A DPDT switch wired so I had Off-1 ON-2 ON allows me to use only as much fan as needed to maintain 35 degrees in the refer. A couple pieces of aluminum angle, some 12 gauge bare copper wire and four electrical box ground clips made a great support, just using the ground clips to secure the wire to the fins, forming a loop at the other end, and screwing the loop to the angle brackets holding the fans was all I needed to mount the fans.
It really takes two fan setups to get the most out of the refrigerator. Cooling the back where evaporator and condenser are is important but getting the cool air distributed in the refer helps the system generate more "cool" both in the refer but in the freezer as well.
In my setup I find that leaving the Titan Fans on Auto, and a single fan running in the refer keeps my freezer down near zero and the refer interior at 35 degrees, all while only drawing less than .5 amp from the batteries. At night the Titan Fans turn off and the computer fan inside the refer only draws .25 amp while running by itself. Easy on the batteries.
You really can't have too much air flow but battery current draw when not plugged in can be an issue which is the beauty of the Titan system. The controller operates the fans only when needed, and in the amount of air flow that's needed.
Even if one doesn't boondock it's not a bad idea to "build" as if you were doing it all the time. Then you're covered during power outages, rest stops along the way when traveling, as well as just turning off fans when not needed to avoid unnecessary wear.
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TitanMike. Is the controller on the titan fan wired? If so, easy to route the wire?
Looks like a great set up.
__________________
Happy Campin!
Forester 2451s
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04-20-2021, 09:32 PM
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#14
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Senior Member
Join Date: Jul 2017
Location: North of Seattle, WA
Posts: 17,263
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Quote:
Originally Posted by Wandering
TitanMike. Is the controller on the titan fan wired? If so, easy to route the wire?
Looks like a great set up.
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Controller is wired. Was fairly easy job. Placed controller above refer, deilled hole just large enough for connector behind controller, then fished wire into vent. Actual routing and difficulty can vary by specific TT or MH.
__________________
"A wise man can change his mind. A fool never will." (Japanese Proverb)
"You only grow old when you run out of new things to do"
2018 Flagstaff Micro Lite 25BDS
2023 f-150 SCREW XLT 3.5 Ecoboost (The result of a $68,000 oil change )
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04-20-2021, 09:36 PM
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#15
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Senior Member
Join Date: Jul 2017
Location: North of Seattle, WA
Posts: 17,263
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Quote:
Originally Posted by nvs4602
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I have a couple of these but chose the Titan Controller because of it's automatic variable speed as well as manual speed control as well.
These are just On/Off controllers which may work well for many.
Since I am mostly off grid I am an electricity miser which the variable speed feature gives me. Only milliamps when fans are on low.
__________________
"A wise man can change his mind. A fool never will." (Japanese Proverb)
"You only grow old when you run out of new things to do"
2018 Flagstaff Micro Lite 25BDS
2023 f-150 SCREW XLT 3.5 Ecoboost (The result of a $68,000 oil change )
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04-21-2021, 11:50 AM
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#16
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Senior Member
Join Date: May 2019
Posts: 1,013
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Quote:
Originally Posted by TitanMike
I agree, don't seal the stack. I left the area ac round the fans open so when they were off, normal convection was unimpeded.
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I had that concern as well (especially since HVAC is my profession), but it was not the case with my install.
I paid close attention last summer and the fans did not cycle any more than when I only had one small fan at the bottom and top and the top vent was 100% open.
The natural convection still moves a lot of air through the fan openings when off. Of course, I still have a lot of open area in the plate, if I were only running two fans I think natural ventilation could be reduced enough to cause the fans to run all the time (assuming they are controlled off temperature of some sort). My fans are controlled off of absorber tube temperature.
When we eventually switch to a 12VDC fridge I'll keep the fans and control them off of cabinet space temperature.
Do you have a link to the Titan controller you're using?
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04-21-2021, 12:18 PM
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#17
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Senior Member
Join Date: May 2019
Posts: 1,013
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Inside the refrigerator I installed dual fans up on the evaporator coil. They are energized whenever the refrigerator is on, but have their own on/off switch for when we're boondocking.
I installed a small squirrel cage blower at the bottom to even out the inside temperature, it's on the same on/off switch as the upper fans.
While I was in there I also put the door seal defrost heater on a switch as well.
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04-26-2021, 01:11 AM
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#18
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Senior Member
Join Date: Mar 2019
Location: Oregon, Washington and Calif
Posts: 205
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Quote:
Originally Posted by 01tundra
... there's no such thing as too much airflow...
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I was going to say that!
But there is a limit to how much energy you can waste.
Pushing air in works better than pulling air out; i.e. you can create a lot more positive pressure than negative pressure, so why not put the fans on the inside of the intake vent somewhere under the evaporator coils?
I turned my absorption fridge into a second food storage pantry, and now use two electric chest coolers for a refrigerator and freezer. Works much better.
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04-26-2021, 10:39 AM
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#19
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Senior Member
Join Date: May 2019
Posts: 1,013
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Quote:
Originally Posted by nic7320
I was going to say that!
But there is a limit to how much energy you can waste.
Pushing air in works better than pulling air out; i.e. you can create a lot more positive pressure than negative pressure, so why not put the fans on the inside of the intake vent somewhere under the evaporator coils?
I turned my absorption fridge into a second food storage pantry, and now use two electric chest coolers for a refrigerator and freezer. Works much better.
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I originally had a push/pull set up with a fan on the intake louver and one at the top of the stack, but there was still a lot of recirculation.
With four fans at the top and a sealed plate the air is only going on way, in at the bottom and out at the top.
I can turn the fans completely off while boondocking with a press of a button via the ARP controller. And while off there's still adequate natural ventilation for the fridge, especially since all of our boondocking is done during the Spring or Fall when temperatures are lower. But even in the middle of Summer when the ambient temperature is in the upper 90's the fans still cycle on/off as they should.
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06-27-2021, 08:46 PM
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#20
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Member
Join Date: Jun 2020
Posts: 87
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Micro Fans on Top?
Lots of good info above and I am particularly interested in TM’s install of the Titan Fans at the roof end of the refer's vent stack. My TT is set up with the ‘intake’ side of the refer right next to where my wife sits in her chair, so having fans at that location is a no go.
@TitanMike: any pics of your set up?
Also, I plan on installing fans inside the fridge, connected in such a way as to only be energized whenever the refrigerator is on. And I plan on using a relay to turn them off whenever the fridge is open based on the light switch.
BUT unlike what is commercially out there and what I have read most folks do as a DIY’er, I am going to use ‘micro’ fans and place them on the TOP of the fins, not the front. The primary reason is I do not want to lose the space to the fan unit. So, this means a really small fan as the height of the space is fairly limited. Turns out they make small fans that will fit in this space. If you search Raspberry Pi 4 Fans you will come up with an assortment and they are about 30x30x7mm.
Has anyone done an install with the fans on top of the fins?
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