Fridge Vent Fan Questions

[TURNKEY]

Two questions, and I would appreciate the wisdom of the crowd:

1-I want to add vent fans to my small 5ver's fridge 'chimney' to improve cooling. I intend to use 2-3 computer fans. I assume it would be better to mount them at the very top of the chimney,(just under the bug screen that caps the chimney below the top roof cap) so as to 'pull' the air up, rather than on the inside of the bottom vent or below the cooling unit and try to "push the air up.

This is based on my belief that the heat generated by the fridge will naturally rise and will build up from the top down in the chimney. Just like an attic fan will cool your house better than trying to push air into your basement with a fan.

2-I don't want the fans to run if it isn't necessary. (We are off grid 95% via solar and I HATE all generators. Even mine.) Therefore I intend on installing a thermo switch to control at what temperature the fans will kick off and on. What temperature should it be rated? And where should it be placed?Norcold 6.3 foot reefer.

Thanks for your help.

[Richard_34]

you can use this technique here:
https://www.bluekeyworld.com/products/cable-management-cord-organizer-wire-clips

[Daniel_85]

for your cables, you can use this wire management solution https://www.amazon.com/Cable-Clips-Management-Organizer-Nightstand/dp/B01H0CEDQC and get rid of clutter easily.

[firestorm79]

Short answer:

1. Both top and bottom
2. 60C (140F) and bottom absorber coil

Long answer:

I originally bought the Valterra fridge vent fan kit that came with a rocker switch and a thermostat. The fan itself was junk and failed after less than a year but I kept the switch and thermostat to use with replacement fans. The best information I can find is the thermostat closes at 60C (140F). I have the thermostat zip tied to the lower absorber coil.

2 120mm Noctua NF-S12A FLX fans sit on top of the vent stack and 1 120mm fan is zip tied to the lower cover.

The fans get power from the fridge light circuit so they only come on if the fridge is on. The Noctua fans are almost silent and keep the fridge temp consistently at 1C (34F). The freezer keeps ice cream hard.

Without the fan setup, the fridge temps varied wildly and took forever to cool down. The freezer would not keep ice cream frozen, especially in hot southern climates.

[Daniel85]

Hi there, I have found a very cool DIY idea. For organizing your cables from your desk, you can simply use these wire holders:
https://www.amazon.com/Cable-Clips-Management-Nightstand-Accessories/dp/B00NVKHLP8

[ajriding]

I found this while looking for switches:
https://www.amazon.com/dp/B0784QTL47/ref=sspa_dk_detail_3?psc=1
Size: 61x45x31mm
It has a temp probe on a wire, and the unit is everything but the fan and battery. It can be mounted inside, by the fridge, and controlled there, but the probe routed to where you need to measure temp.
Seems easier than the temp switch wired to an on/off switch which still has to be routed through to inside of camper…
Anyone use this?

(not looking for opinions of those who up til this point have never seen it…)

[austinjenna]

I mounted a few large computer fans at the top of the fridge vent to suck the hot air out and it works fine for me. Most fans in electronics suck the air out, not blow it in.

[beemerphile1]

ajriding wrote:
...In the spirit of where to mount the fan, has anyone tried mounting it against the outside opening so the fan only draws air from the outside....

I installed an ARP Fridge Defend system with fan. They recommend attaching the fan to the inside of the lower vent cover. Using cable ties made easy work of it.

[portscanner]

I have done this on three different RV's. On each RV, while in Florida, the refrigerator operation was, well, marginal. Doing the following, I had rock hard ice cream

Note - in all the RV's I have had, after studying how the refrigerator was installed vs the installation instructions from the refrigerator manufacturers, discovered, to my dismay, the RV manufacturers did not follow the proper install procedures for baffles and design for the area behind the fridge. I had two options - tear the fridge out and rebuild the back - or just install the fan. I am lazy. I installed the fan.

Get a 12 volt, two wire, 90 mm fan - or the biggest one your can mount, i.e 100mm or 120mm. But note - the bigger in size the fan is - usually the larger the current draw! Just one - that is all you need. You dont need 100's of cubic feet of air a minute - you just need the air to move. Put it at the bottom of the fridge, just inside the access panel (the access panel on the outside of the RV.) Mount it horizontal, i.e. so that it blows up, uh...I mean so the direction of air flow is upward. On two of my RV's there was a lip I could screw directly into. On the third, I got a small piece of wood and glued it using yellow wood glue inside/above the outside access panel and then screwed into that. I would mount it about in the middle - but it can be a little more left or right depending on obstructions to mounting it. But I would have at least a few inches between the burner and the fan - just to be safe. You may have to get a little creative on your mounting bracket if need be

Get a Emerson 3F05-1 Adjustable Snap Disc Fan Control. Adjust it for 110F. Select a location on the condenser coils on the back of the fridge that you can tie wrap (these things not twist ties - you dont have to get specifically this make/model - but use the black ones - they last longer) it to the coils.

Use 16-18 gauge wire and crimp on spade connectors - make sure you use a proper crimping tool - not a pair of pliers!!!

Wiring - IMPORANT - unplug the shore (110 volt) power cord. Disconnect the batteries using either your battery disconnect switch, remove the primary in line fuse, or disconnect the connections from the house batteries.

On the back of the refrigerator (accessed through the exterior panel) Find the stud on your refrigerator control board for the refrigerator interior light. If there is no interior refrigerator light, it will not be used, so just plug into it. If you have an interior light, splice into that wire and connect it to one side of the thermostat you installed. Connect the thermostat to the fan (usually a red wire on the fan.) Connect the black wire from the fan to ground. Confirm the

Voila! After you re-connect your battery, you have a fan that will only run when the fridge is turned on AND the cooling cycle is running!

[trail-explorer]

Norcold has a thermal switch made just for this purpose.

[CincyGus]

I have a residential fridge now but in my previous camper, I mounted one of these on the lower of the two vents by the fridge with a simple inline switch. 200mm Fans are used often in the top of computer cases for high powered gaming computers for a couple reasons. One, they move significant amounts of air at a lower, quieter RPM. Because of being oversized from the 120mm fans most computers have and being on top, they act much like the attic fan referenced earlier and do so nearly silently.

I only turned it on when it was 85+ but it made all the difference in the world of the fridge struggling to stay in an acceptable range or it doing a great job on the dog days of summer.

NOCTUA 200mm Fan

This is a top quality computer fan brand.

[NRALIFR]

Heat, in the right amount and in the right areas of the cooling unit, is necessary for an absorption refrigerator to work properly. A correctly installed fridge shouldn’t need any more than a small airflow assist in doing what will occur naturally. Heat rises, and as long as the upper and lower vents are sized according to the installation guide, and the proper clearances and baffling are maintained, the air WILL flow up across the coils and out the upper vent.

It isn’t necessary to fill the roof vent or chimney with fans in order to make the fridge work. By doing that, you’ve effectively reduced the size of the upper vent by about half, and possibly created an environment where the fridge couldn’t function without the fans. You shouldn’t want that any more than you’d want a bird building a nest on top of the chimney screen under the roof vent cap.

At the most, a single 120mm computer fan placed in the area between the upper and lower coils is all that I would install. I would choose the fan type by how quiet and durable it is, not on how many cfm’s it moves. It doesn’t take much.

:):)

[Wishbone51]

has anyone tried mounting it against the outside opening so the fan only draws air from the outside?

I'm in the process of doing this myself. For now, I bought a small 110V muffin fan that I'm just placing (not mounting yet) just inside the fridge panel. Will see how much it affects temperatures when it gets hot out.

For fun, I turned it on while starting up my fridge.. Was 50* outside, and it seems that it actually slowed down the fridge cooling. When I turned off the fan, it started cooling faster. I guess it requires some heat to operate. I'll test again when the temperatures rise.

[philh]

I'm going to disagree, pulling the air out the top will move a lot more air. It's already taking advantage of the natural flow direction... up. I could make an argument for also gaining an advantage of creating flow across the fins, but that will not help much moving air out of the "chimney".

[ajriding]

Dumb question here….

I agree, it makes sense to blow air towards the fins rather than pull it towards them (below or above mounting), but some turbulence will occur, circulating air around inside rather than a continuos flow from outside bottom, to outside top.

In the spirit of where to mount the fan, has anyone tried mounting it against the outside opening so the fan only draws air from the outside? (not just swishing air around inside the compartment).

Not sure if this is even enough of a difference to matter, but I am about to mount a fan in mine. I will not be able to remove the fridge so likely will mount it in the area of the side opening that I can access.