Fridge cooling

GrampaKilt · July 15, 2020, 08:44:36 PM

The good news about several thermostatically controlled external fans is that I can finally keep the inside of the fridge cool. The bad news is that keeping the inside fridge temp consistent takes day to day adjustment of off/on fan temps. Perhaps this negative is more of a function of camping in northern Canadalands where wild swings of temperatures are commonplace. GK

Sylvain · July 16, 2020, 06:11:30 PM

Quote from: Merlin on July 15, 2020, 07:51:04 PM
On at 100F and off at 80F. So in typical summer temps here in Michigan, it runs afternoon/evening and is off night/morning. Unless the compartment is in the direct sun, then on all but early morning.

Thanks for the great info Merlin. I thought the on/off temperature would be the same. I feel like there is quite a gap between the two temps. Can we adjust the on/off temps?

Sylvain · July 16, 2020, 07:27:38 PM

Quote from: GrampaKilt on July 15, 2020, 08:44:36 PM
The good news about several thermostatically controlled external fans is that I can finally keep the inside of the fridge cool. The bad news is that keeping the inside fridge temp consistent takes day to day adjustment of off/on fan temps. Perhaps this negative is more of a function of camping in northern Canadalands where wild swings of temperatures are commonplace. GK

GK, do you use the same fan?

You are so right about Canadalands GK! A few days ago we had temps of 32'c and very humid. Today it's 18'c and bone dry!!

Merlin · July 16, 2020, 09:20:45 PM

Quote from: Sylvain on July 16, 2020, 07:27:38 PM
Quote from: GrampaKilt on July 15, 2020, 08:44:36 PM
The good news about several thermostatically controlled external fans is that I can finally keep the inside of the fridge cool. The bad news is that keeping the inside fridge temp consistent takes day to day adjustment of off/on fan temps. Perhaps this negative is more of a function of camping in northern Canadalands where wild swings of temperatures are commonplace. GK

GK, do you use the same fan?

You are so right about Canadalands GK! A few days ago we had temps of 32'c and very humid. Today it's 18'c and bone dry!!

No adjustments and you would not want to. The temp gap keeps the fan from short cycling (frequently starting and stopping).

(Oops, replied to the wrong thread. Oh well)

GrampaKilt · July 17, 2020, 01:14:19 PM

I have not found a linear relationship between external fan OFF/ON, external air temps, the temp in the fridge coils and internal fridge temps, so that one OFF/ON setting does it all.

My first fan iteration of 2-5" computer fans exhausting at the upper vent was ineffective. I finally used the idea found here https://www.arprv.com/rv-fridge-fan.php , that of installing 4" squirrel cage fans, one at the lower vent, one at the upper. Pricey ARPRV's fans (proprietary?) were to tough to spec online (0.2A draw and 1800 rpm) but I finally found something close in Aliexpress. The fans are controlled by this inexpensive temp controller https://www.amazon.ca/dp/B07VRNM9FS/ref=dp_prsubs_2 . The sensor is attached to the bottom coil per ARPRV's recommendation. Currently the OFF/ON differential is set for 15 degrees with OFF being 95F.

This fan configuration really moves the air! Lately, I've experimented with the COLD to COLDEST temp button instead of adjusting external fan OFF/ONs. This is working most of the time.

A second controller (same brand) regulates the fans inside the fridge https://rvcoolingunit.com/Norcold-Evaporator-Fan-Greater-inside-Cooling-Custom-Deluxe-wGrill-P3239953.aspx . The OFF/ON differential for this one is 5 degrees, OFF is 37F.

A couple of asides.
1. I left the 5" fans insitu which happen to be lighted, one red, the other green. If the fans are running in the evening, the glow emanating from the upper grill is pleasantly eerie.
2. I struggle mightily with English translations of Chinese instructions so that once I finally 'get' it, I rewrite them for future reference. If any are interested the temp controller above, FWIW, here is my rewrite. https://drive.google.com/file/d/1htdPDo9QEqIGwLUx2WZ8PJyweebgNwWv/view?usp=sharing

Regards, GK

Sylvain · July 20, 2020, 05:14:18 PM

Quote from: Merlin on July 16, 2020, 09:20:45 PM
Quote from: Sylvain on July 16, 2020, 07:27:38 PM
Quote from: GrampaKilt on July 15, 2020, 08:44:36 PM
The good news about several thermostatically controlled external fans is that I can finally keep the inside of the fridge cool. The bad news is that keeping the inside fridge temp consistent takes day to day adjustment of off/on fan temps. Perhaps this negative is more of a function of camping in northern Canadalands where wild swings of temperatures are commonplace. GK

GK, do you use the same fan?

You are so right about Canadalands GK! A few days ago we had temps of 32'c and very humid. Today it's 18'c and bone dry!!
No adjustments and you would not want to. The temp gap keeps the fan from short cycling (frequently starting and stopping).

(Oops, replied to the wrong thread. Oh well)

Ok! Thank you so much Merlin.

Sylvain · July 20, 2020, 05:28:17 PM

Quote from: GrampaKilt on July 17, 2020, 01:14:19 PM
I have not found a linear relationship between external fan OFF/ON, external air temps, the temp in the fridge coils and internal fridge temps, so that one OFF/ON setting does it all.

My first fan iteration of 2-5" computer fans exhausting at the upper vent was ineffective. I finally used the idea found here https://www.arprv.com/rv-fridge-fan.php , that of installing 4" squirrel cage fans, one at the lower vent, one at the upper. Pricey ARPRV's fans (proprietary?) were to tough to spec online (0.2A draw and 1800 rpm) but I finally found something close in Aliexpress. The fans are controlled by this inexpensive temp controller https://www.amazon.ca/dp/B07VRNM9FS/ref=dp_prsubs_2 . The sensor is attached to the bottom coil per ARPRV's recommendation. Currently the OFF/ON differential is set for 15 degrees with OFF being 95F.

This fan configuration really moves the air! Lately, I've experimented with the COLD to COLDEST temp button instead of adjusting external fan OFF/ONs. This is working most of the time.

A second controller (same brand) regulates the fans inside the fridge https://rvcoolingunit.com/Norcold-Evaporator-Fan-Greater-inside-Cooling-Custom-Deluxe-wGrill-P3239953.aspx . The OFF/ON differential for this one is 5 degrees, OFF is 37F.

A couple of asides.
1. I left the 5" fans insitu which happen to be lighted, one red, the other green. If the fans are running in the evening, the glow emanating from the upper grill is pleasantly eerie.
2. I struggle mightily with English translations of Chinese instructions so that once I finally 'get' it, I rewrite them for future reference. If any are interested the temp controller above, FWIW, here is my rewrite. https://drive.google.com/file/d/1htdPDo9QEqIGwLUx2WZ8PJyweebgNwWv/view?usp=sharing

Regards, GK

Thanks for sharing GK! This might be very useful!

dlb53151 · July 25, 2020, 12:48:58 AM

Thanks Paul and Merlin. If I understand correctly I just need to buy that one Valtera fan (versus dual fans and other fancy setups) and position / wire it like you showed. I'll plan to get that done this summer and will let you know if I have any questions.

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