Two Zone Club

[teotwaki]

Hey Jim - I want to check out your fridge when I get home, so I can decide if I want a 45 with Two-Zone or a 60...

I'll buy you a beer or something.

When you get home we can get some folks together and have that beer somewhere off-road at a camp fire!

 

[SAR_Squid79]

Fine by me!

 

[teotwaki]

I'd like to see what you come up with Make sure you post it up when you've made it!

Parts kit:

1. 1.5 x 1.25 inch sched 40 PVC flange with internal threads (thick walls)
2. 1.5 x 1.25 inch sched 40 PVC flange
3. 1.0 x 1.5 inch sched 40 sleeve
4. 1.0 inch sched 40 elbow 45 degree angle
5. 1 mini brushless DC fan
6. 4 stainless 4-40 x 1 inch screws
7. 1 can PVC glue, clear
8. zip ties

 

[teotwaki]

I took the thicker threaded flange and drilled four holes with a number 43 tap sized drill for 4-40 screws

I sealed the gaps with some white bathtub RTV/caulk

Test fit before gluing

 

[teotwaki]

Inspired by MrBishi's tie wraps

Ta-Da!


I've got some rough ideas for testing the effectiveness so I'll do that tomorrow. The top elbow is not glued in so that I can adjust the position a bit.

 

[mrbishi]

looking good Jim - nice and compact. What sized fan did you use? I looked had a look at mine and its a low power draw 80mm - only 0.09 amps.

 

[Gear]

Hello Jim,

Looks Great, I hope you are making more than one!! :sombrero: Do you have a source for the fan you are using. While you are at it could you post up pictures on how you are going to hook it up.

Thanks

 

[mrbishi]

Justin - any computer shop will be able to supply you with different sized 12v computer fans. 80mm is most common but you can easily get 60mm and 40mm. The "silent" ones normally draw the least amps and move enough air for this purpose.

I've tapped into the 12v power supply inside my Engel behind where the 12v cord hooks into it.

 

[dclee]

Great mod! I have been contemplating the Two Zone for a long time. This makes it even more appealing.

One idea I had, put an inline on/off switch for the fan. That way you can turn it off if the fridge is not full and you are not using the upper section.

 

[teotwaki]

looking good Jim - nice and compact. What sized fan did you use? I looked had a look at mine and its a low power draw 80mm - only 0.09 amps.

That is a nice low current draw. I measured mine and it is almost double yours at 176 Ma at 12 vDC. Not very good in comparison but of no real worry to my dual battery system in the truck.

I loaded up the fridge with water bottles and put in two temp probes. Right now it is cooling down. Once it is around 40-ish degrees F in the lower compartment I'll turn on the fan in the Two Zone and see what happens.

If this was more scientific I'll bet we could calculate how many CFM the fan should be but I just grabbed the smallest one I had in a box of DC fans. We know MrBishi's bigger fan works very well so that is our upper limit set point. It may be that the bigger fan is needed in order to suck up enough cold air from the lower compartment.

We could get much fancier with a temp probe in the upper Two Zone compartment and a circuit to trigger the fan, but not right now.

 

[teotwaki]

I got home about 15 minutes ago and saw the lower fridge temp probe was at 46.6 degrees and the upper temp probe by some water bottles had dropped from about 72 degrees to 69.5 degrees. I started around 9 or 10 AM this morning and had to leave the house for a while.

Then I switched on the little "turbo"fan. After only 5 minutes the upper temp had dropped to 67.4 deg F and the lower chamber rose a little bit to 47.0 degrees.

I will be home only an hour so I'll get one or two readings before I go and then grab one when I get home later.

 

[teotwaki]

one hour later the upper chamber was at 64.8 deg F and the lower was at 45.7 deg F

 

[mrbishi]

Jim - do you have anything in the TwoZone? I've never tested mine empty but I know when I have it full with cans of beer/softdrink and water it cools very quickly and gets to the same temp as the fridge.

Perhaps when the TwoZone has contents the cold air "spills" over them and distributes better and thus the cooling effect is more efficient?

 

[teotwaki]

Jim - do you have anything in the TwoZone? I've never tested mine empty but I know when I have it full with cans of beer/softdrink and water it cools very quickly and gets to the same temp as the fridge.

Perhaps when the TwoZone has contents the cold air "spills" over them and distributes better and thus the cooling effect is more efficient?

Yes, a bunch of large and small water bottles filling top and bottom compartments.

At 12:30 AM I just measured 36.9 deg F in the bottom and 50.9 deg F in the top.

 

[teotwaki]

8:45 AM report

The fridge compressor was not running, upper compartment was at 46.2 deg F and the lower compartment was at 36.5 deg F. The little fan has been running continuously since the start of the test. Ambient temp is 74 degrees and the TwoZone and Engel have the insulating covers.

The data that I've collected mirrors what MrBishi has accomplished so anyone with a TwoZone can build a simple fan modification and obtain lower temps in the upper compartment.

The Two Zone test setup with instruments and a small DC supply to run the fan.


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