DIY (Mini Bar Fridge) Chiller by C-BuZz

G'day guys,

Summer completely rolled me this year, totally caught me off guard. Temps hit 35c the other day & almost whiped out my minireef. Lost a few corals & everything was looking really bad :-[ Tank water temps were sitting on 33c . I built this little unit using a barfridge compressor & re-engineered the plumbing & added a couple of goodies to increase performance






Overall shot after I've tidied her up a bit:


Got it setup at the front just for testing to see if the system needs adjusting before it goes at the back:


Fully insulated the tub:




Chiller at home at the back of tank. It's really quite a small chiller, fits in there nicely.




This pulled my 90L tank temps from 33c to 25c in about 2hrs in 35c ambients, at which point my tank heaters kicked in. I had to switch the device off in the end as my tank temps where still dropping All up this cost me just under $100AUD. I'm going to be getting one of these bad boys to use with it:

http://www.reefshops.com/digital-dual-mode-heater-and-cooler-controller-atc800.html

To regulate the tub temps.

Cheers

C-BuZz

 

I hate to be the first to say it, but that copper is going to cause you a lot of troubles..

 

yeah couldn't you just take an old minifridge and run some vinyl tubing through it as an inexpensive chiller set-up?

 

Glad you brought this up & I should have mentioned it in the op.

The tub with the copper pipe is the heat exchanger. The evaporator you see submerged in the water freezes to around -10 which in turn cools the water it's submerged in. The tank water is pumped out of the tank through the tubes, the tubes run through the freezing water & back into the tank. None of the water from the Resorvior is pumped into the tank & vice versa.

No, a minifridge will not be able to maintain the tanks heat output.

C-BuZz

 

Oh, that makes sense now.. thanks.. Welcome to 3reef..

 

LIES! i bet it will. seriously though a fan over the surface is usually good for a 2-4 deg drop.

 

Try it, dare ya!

C-BuZz

 

If you search the forum, you'll find the idea of the mini-fridge for chiller use is well discussed. It's been tried many times by many folks; and unfortunately the heat exchanger portion of the unit is the downfall. Without using stainless steel or titanium coils, there simply is no efficient way to get the cold from the fridge's interior into the water that flows through it. If you used a large coil of poly tubing in the fridge, the tubing itself is such a strong insulator that the water doesn't become cooled.

Now if you invested in a good quantity of stainless steel or titanium tubing, the price you pay will be tantamount to the price of the very chiller you're trying to avoid buying.

Of course, there's always a first--so if you figure out how to accomplish the bar fridge/chiller trick; make sure to patent it.

 

Even with titanium/copper tubing the fridge will not cope with the heatload. Fridge's are not designed to cool a constant heatload which most don't realise & will more than likely shutdown due to increased high side pressure &/or overheating of the compressor. That coupled with no active cooling on the very inefficient condensors refrigerators have.

Mini bar fridge compressors on the other hand, can actually cool a lot more heat than one would expect. This particular compressor should be able to handle up to around 150w-200watts without to much trouble if the condensor is dispersing the heat efficiently enough. If the condensor is not adequate the compressor will overheat resulting in a shutdown or damaged compressor (which is what will happen if you try to use a normal bar fridge).

There will be some trial & error getting the capillary tube length, also the charge right. But once you get both of those things sorted it should work great.

C-BuZz

 

What if you pumped water into a thin DIY reactor that sits inside a mini fridge then back to the tank? Or how about some kind of ATO reservoir cooler, the volume into the tank wouldn't be much, but 36-40* drops of water might have some kind of positive effect.

~Will.