Fridge cooling

MitchB · July 18, 2019, 10:57:38 AM

I know hot weather cooling of the fridge can be difficult so I've modded an upper vent panel to include a fan and a thermostat. I'm hopeful that when the back of the fridge cabinet gets hot the additional airflow will cool it enough to allow better heat transfer though the outer coils. For power I'm running it to a portable battery box I use but there is an easy tap in to 12 volts right at the base of the fridge. From a parts perspective this thing is pretty cheap to build, a Dometic vent panel for $25 (don't want the fan stuff on while traveling), a thermostat controller for $7 and the weatherproof box for the thermostat $22. If anyone is interested I'll link the parts on Amazon.

Mitch

DavidM · July 18, 2019, 11:43:43 AM

MitchB:

While I have never had a problem with fridge cooling in our NE US climate, I am intrigued by your design. Some questions:

I assume that the spare Dometic panel is so that when you reach your destination you can pull off the existing panel and replace it with this one with the fan and controls, right?'

Why don't you want it on when traveling?

Why do need a thermostat? These small DC fans draw very little current so you could just power it from a switched source in the fridge and leave it on all of the time. Or you might be able to find a DC source in the fridge that is thermostatically switched to power it with. Maybe the burner solenoid valve for LPG use or an AC relay for AC use or both with a couple of diodes.

David

MitchB · July 18, 2019, 11:56:08 AM

Hey David,

Yes you are correct about installing the modified panel after arrival. In my configuration since I'm using a separate power supply I'd have to manage the wires plus the fan itself isn't really an outdoor type of fan so if I were to hit some wet weather during travel it could be damaging. Everything is pretty secure so it's more about the electronics than the danger of it falling off.

With respect to the thermostat, I had it and it's cheap as sin so I used it rather then tie into something in the trailer itself. Plus, while the draw of the fan is only .25 amps that's 6 amps over the course of the day and I boondock medium to long periods of time so battery is a consideration. I could tap the fridges 12 volt source, it's right there and I might in the future but for the moment I prefer using a different power source.

Powder Hounds · July 18, 2019, 01:00:54 PM

Hello,

Have a look at the products from arprv.com , they provide fridge protection devices along with a single or dual fan ventilation systems.

Cheers!

Merlin · July 18, 2019, 02:03:05 PM

Very clever! Replacing the entire vent cover with a fan unit is something I never thought of.

I installed this Valterra fan and have used it for 2 years. I have no data on increased efficiency, but it helps me think I'm improving efficiency whenever I hear its gentle hum as a walk around the back of the camper outside

https://www.amazon.com/Valterra-A10-2618VP-FridgeCool-Exhaust-Fan-12/dp/B002N5YDG2/ref=cm_cr_arp_d_product_top?ie=UTF8

This is mounted inside the external fridge compartment on an existing bracket about halfway between the upper and lower coils. It definitely improves air flow when the included thermostat turns it on. I hardwired it into the 12V available in the compartment.

ADR · July 18, 2019, 07:46:33 PM

I've run fans on many fridges over the years- never mounted one outside though- I like it inside the panel out of sight and out of the weather.
12V computer fans work great- I usually use a pair with an mechanical thermostat so no power is drawn when cooling isn't needed.

They are mostly needed because many RV builders do NOT follow the fridge makers instruction on proper installation as to baffling and airflow.
The fridge installs with the upper vent in the wall rather than in the roof usually perform worse and benefit from fans the most.

MitchB · July 18, 2019, 11:47:18 PM

I could mount the fan on the inside of the vent cover, do you have a thought on whether that would increase or decrease the amount of air moved out of the cabinet? There's not much room between the vent and the back of the fridge.

Merlin · July 19, 2019, 05:47:22 PM

Quote from: MitchB on July 18, 2019, 11:47:18 PM
I could mount the fan on the inside of the vent cover, do you have a thought on whether that would increase or decrease the amount of air moved out of the cabinet? There's not much room between the vent and the back of the fridge.

Inside and with a clear airflow to the entire fan seems like it would improve cooling the most. Could you mount the fan horizontally at the bottom of the vent and still have clearance with the back of the fridge?

Merlin · July 19, 2019, 05:54:21 PM

Quote from: Merlin on July 18, 2019, 02:03:05 PM
Very clever! Replacing the entire vent cover with a fan unit is something I never thought of.

I installed this Valterra fan and have used it for 2 years. I have no data on increased efficiency, but it helps me think I'm improving efficiency whenever I hear its gentle hum as a walk around the back of the camper outside

https://www.amazon.com/Valterra-A10-2618VP-FridgeCool-Exhaust-Fan-12/dp/B002N5YDG2/ref=cm_cr_arp_d_product_top?ie=UTF8

This is mounted inside the external fridge compartment on an existing bracket about halfway between the upper and lower coils. It definitely improves air flow when the included thermostat turns it on. I hardwired it into the 12V available in the compartment.

If I were a RV full-timer, I would sure consider these. They are bit too spendy for a casual RV'r like me. Have you installed one in your camper?

MitchB · July 19, 2019, 06:15:45 PM

Quote from: Merlin on July 19, 2019, 05:47:22 PM
Quote from: MitchB on July 18, 2019, 11:47:18 PM
I could mount the fan on the inside of the vent cover, do you have a thought on whether that would increase or decrease the amount of air moved out of the cabinet? There's not much room between the vent and the back of the fridge.

Inside and with a clear airflow to the entire fan seems like it would improve cooling the most. Could you mount the fan horizontally at the bottom of the vent and still have clearance with the back of the fridge?

I did cut away the vent behind the fan so it's unobstructed airflow. We'll see if it works, next week I leave for a 2 week boondocking trip.

Merlin · July 19, 2019, 08:23:57 PM

One more quick question. How will you keep the sealed thermostat box from getting too hot in the sun and too cold at night? Maybe that doesn't matter?

MitchB · July 19, 2019, 10:48:37 PM

Quote from: Merlin on July 19, 2019, 08:23:57 PM
One more quick question. How will you keep the sealed thermostat box from getting too hot in the sun and too cold at night? Maybe that doesn't matter?

I'm cautiously optimistic that it won't matter. We'll see.

tinkeringtechie · July 20, 2019, 10:12:34 AM

I was just playing around with cooling on my own fridge last week. In my case I was trying to prevent the existing thermostatic fan from kicking on because it seemed to be running too often. I was planning to either assist with airflow (taking off the cover will stop the fan within seconds), or using a lower power/quieter fan. So my first question to everyone that has responded so far: Do you have a stock fan at all? It doesn't sound like it. My trailer came from the factory with a relatively small Sunon that makes a bunch of noise and doesn't seem to do much. It's mounted on a bracket near the top of the cabinet, but points up. My idea was to install an array of larger, lower power fans (like 120mm Noctua industrial) on a baffle so that the air has to leave the cabinet instead of just swirling around in circles. I was hoping to keep the power the same or lower than the existing fan so that I could just steal its power connection. Any thoughts?

Merlin · July 20, 2019, 11:04:12 AM

My '15 16TBS with a single door Dometic 3-way fridge did not come with an external fan. The 2 rear- facing vents have what I think is very poor circulation for the cooling fins in the exterior compartment. I like the idea of a baffle in there to force the air up and out. I do think the single fan I added pointing up in the central part of cabinet helps, but for sure a lot of the air it moves just circulates internally. It also runs pretty much all the time, though the thermostat turns it off on cool nights. It is quiet when running. Installing an array of fans pointing out (or a single fan like MitchB) sounds good. That compartment gets HOT!

MitchB · July 20, 2019, 12:30:23 PM

No fan came on mine either and as Merlin said that compartment gets very hot. There is essentially no air circulation around the cooling fins because they are above the highest vent in the vent panel. I thought about a baffle above the fridge but the available space is small and a baffle would still be above the vents and mounting would have been a challenge. Last year as I was pondering this issue I even thought that perhaps the fridge wasn't installed correctly given the tight space but it is. I think my solution will help, we'll see. It can certainly stand some refinement if I find it's worthwhile.