Can I get all the hard-core, pipe-hitting ATOT engineers and scientists up in this thread?

[SaltyNuts]

I want to make a chiller for my soon-to-be outdoor aquarium. It has to survive the HOT Houston weather. And I want to do it on the cheap.

So, I'm generally going to go by this video:

However, a few things. Rather than a refrigerator, I'm going to use a small freezer, something like this:

https://www.bestbuy.com/site/insign...Vi4bACh0hNA2JEAQYAyABEgILvfD_BwE&gclsrc=aw.ds

Why on earth someone would use a refrigerator over a freezer, when the latter has much more cooling capacity, I don't know.

With that, any other tips, tricks or suggestions? Some particular questions:

Where should I drill the holes for the hose entrance and exit? One high, one low? Vice versa? Does it really matter?

Isn't there something I can put through the holes to make a better, tighter fit, other than just expandable foam? Like a "grommit" or something?

What kind of hose should I use? He used a garden hose because he said it is insulated, but wouldn't you NOT want it insulated if the idea is to make hot water cold via the hose contact with the cool air in the freezer?

Maybe some kind of copper hose is best?

I take it hose that is longer, with a smaller diamater, is preferred over shorter, wider hose, so that there is more area contact overall and the water stays in contact with the cool air longer?

That's it for right now, any and all help is appreciated!

Thanks!!!

 

[SaltyNuts]

LOL, 122 views and not a single reply? How these supposed "big brain" ATOTers scatter when a thread with some real thought requirements pops up!!!

 

[Greenman]

Is the aquarium fresh or saltwater?

 

[MagnusTheBrewer]

You might try a wort chiller that can be found at most brew supply stores.

 

[JEDIYoda]

Houston has a downtown aquarium. Perhaps they might have some ideas...

 

[sdifox]

you and on the cheap = dead fishies

 

[Humpy]

I want to do it on the cheap.

Wrong forum pal.

Everyone here just calls up their outdoor aquarium chiller guy to take care of it.

 

[BoomerD]

Wrong forum pal.

Everyone here just calls up their outdoor aquarium chiller guy to take care of it.

And, sorry...I'm not taking on new (cheapskate) customers.

 

[SaltyNuts]

Is the aquarium fresh or saltwater?

Freshwater 100% bro!!!

 

[SaltyNuts]

And, sorry...I'm not taking on new (cheapskate) customers.

You guys sound like just a couple of trolls. But the world needs some trolls, I guess...

 

[brianmanahan]

why on earth would anyone make an aquarium out of a fridge

 

[squirrel dog]

take the fish and kill them now .

 

[Greenman]

Fresh water is easy. Since the water will be pumped through the system, it doesn't matter where the holes in the refer go, put them where it's convenient. Inside the refer I would use copper pipe, and convert to vinyl or plastic when it exits. I'd also insulate it.

 

[Schmide]

Unless you have an outdoor fish tank, air conditioning the room it's in seems like such a better option.

 

[deadlyapp]

Smaller line diameter with thinner wall and metal material will be best for heat transfer within the freezer. You'll run into some significant restrictions for flow with length and diameter though, so I recommend creating some sort of "header" that is larger diameter and splits into many smaller lines, this is basically what a heat exchanger looks like internally. Outside the freezer you want to insulate as best as possible, use thicker material, larger lines, and even foam insulation if possible.

At the interface to the freezer, doesn't matter much - a foam spray insulation would be fine.

I would recommend putting a couple of fans maybe inside the freezer itself to blow over the coils, it will help with heat transfer.

If you really wanted to get tricky, you could make a water tower inside the freezer - make some sort of shower head that sprays water through the air and then collects in a basin at the bottom with a second pump to pump it back to the aquarium.

 

[Paperdoc]

I'm no engineer, but a reasonable handyman, so I'll offer suggestions.
1. The video used a small fridge mainly becasue it was cheap second hand. Finding a small freezer like that is not likely or cheap. A freezer MAY not have more cooling power than you need - it might just have better insulation in its walls. But bear this in mind also: you must NOT run the fridge or freezer thermostat temperature setting too low, or it can freeze up the water flowing through the coiled hose inside it - and no more flow! You really should have some way to check the OUTLET water flow temperature to be sure it is not too low. So, even if a small freezer might have greater heat removal capacity from a larger refrigeration unit, you cannot run it an COLDER that you would with a fridge.
2. Fridges and freezers are built differently. A fridge concentrates all of it s cooling inside into the freezer unit at the top, so you know where the sealed cooling system is. A freezer (or at least, the larger freezer chests used for food) place cooling tubes all though the WALLS of the unit with insulation outside of them. So virtually every wall is NOT a place to start drilling holes! If you use a freezer, I suggest the only safe area for the holes would be in the door.
3. Again thinking for cheap, the video simply used two coiled lengths of garden hose, even though it is insulated and that would interfere with heat transfer. You would get much better performance if you used a length of metal tubing. In hardware and plumbing stores you can buy soft copper tubing in a coiled roll just like a hose - this is not the same as the hard copper pipes one uses for water supply lines under pressure. This stuff is flexible enough you could straighten out the ends and position them to go though your holes in the outer wall.Then,of course, you'd want a way to fasten to each end a fitting to connect to the common garden hose connectors. NOTE that, if you need to make significant bends in this type of tubing, they need to be gentle - there are special tubing bending tools for this. Too sharp a bend will just collapse the tubing. The copper tubing would come in a fairly tight coil. You should try to expand it out somewhat so the coils all have free air flowing between them. What really will have to happen is that the AIR inside the fridge must get cold from contact with the freezer unit cooling structure, and then it must flow around the fridge and between the coils so it can make contact with the coils and remove heat from them.
4. Actually, insulated garden hose is a good idea between the pond and the fridge unit - the more insulated, the better. It is inside the fridge (and in the pond? - see item 5 below) where you want fast heat flow though the tubing walls.
5. Installing a small fan inside the fridge would greatly improve the flow of air and increase heat removal rate from the coils. But that's added cost and complexity, and it adds a heat source inside the fridge. You may not need that much heat removal improvement - just the unassisted air flow inside may be sufficient if you have enough coiled (copper?) inside.
6. The video makes no mention at all about what is in the pond. It appears to assume that you will connect a normal pond water circulation pump and simply pump the pond water trhough this hose and refrigerator system and back into the pond. I am sure you are well aware of the issues of algae growth and pond cleaning. So you can appreciate that the same algae growth process will occur inside your hose and cooling coil. Cleaning that out to prevent clogging would be a big problem! You might be better to arrange another copper coil at the pond end, submerged in the pond, and keep the entire cooling system as as a separate closed system loaded with just plain water. This would generate MUCH less contamination within the cooling loop, and you could flush it more easily and less often.
7. If you are concerned about having copper in direct contact with the water in your fish pond (either in the fridge coil, or in the pond coil) you could use instead some type of plastic tubing you consider safe for fish. Just try to get something that does not have a thick wall to try to maximize the transfer of heat through it. But then you might need a longer length at each location to compensate for the slower rate of heat transfer (compared to copper).

 

[deadlyapp]

I'm no engineer, but a reasonable handyman, so I'll offer suggestions.
1. The video used a small fridge mainly becasue it was cheap second hand. Finding a small freezer like that is not likely or cheap. A freezer MAY not have more cooling power than you need - it might just have better insulation in its walls. But bear this in mind also: you must NOT run the fridge or freezer thermostat temperature setting too low, or it can freeze up the water flowing through the coiled hose inside it - and no more flow! You really should have some way to check the OUTLET water flow temperature to be sure it is not too low. So, even if a small freezer might have greater heat removal capacity from a larger refrigeration unit, you cannot run it an COLDER that you would with a fridge.

Just a clarification about this statement and kind of how fridges & freezers work. You are correct, there is generally no distinction in the cooling circuit between a fridge and a freezer, mixed fridge/freezer combinations simply take the colder air (which is a fixed temperature) and use a mixing valve to cool the fridge. The temperature of the freezer and fridge is maintained by cycling the cooling system more or less frequently.

Using a freezer instead of a fridge (as they are normally configured) will absolutely produce better heat transfer to the liquid running through it because heat transfer is based on the temperature difference between two liquids. Now, could you take a fridge and modify the thermostat to go to a lower temperature? Sure, in which case you're right, the only thing that affects anything is the insulation in the body.

I would not worry about the liquid in the lines freezing. I assume that the flowrate you will be pushing through there will prevent any sort of issues. I would worry about the fridge/freezer running constantly though - the compressors are not designed to run 100% of the time, and if you're constantly putting in warm water then the thermostat will always think that it needs to operate.

 

[BoomerD]

Just a clarification about this statement and kind of how fridges & freezers work. You are correct, there is generally no distinction in the cooling circuit between a fridge and a freezer, mixed fridge/freezer combinations simply take the colder air (which is a fixed temperature) and use a mixing valve to cool the fridge. The temperature of the freezer and fridge is maintained by cycling the cooling system more or less frequently.

Using a freezer instead of a fridge (as they are normally configured) will absolutely produce better heat transfer to the liquid running through it because heat transfer is based on the temperature difference between two liquids. Now, could you take a fridge and modify the thermostat to go to a lower temperature? Sure, in which case you're right, the only thing that affects anything is the insulation in the body.

I would not worry about the liquid in the lines freezing. I assume that the flowrate you will be pushing through there will prevent any sort of issues. I would worry about the fridge/freezer running constantly though - the compressors are not designed to run 100% of the time, and if you're constantly putting in warm water then the thermostat will always think that it needs to operate.

The problem with that is controlling the tank temp. If the "chiller" runs 24/7, then it will quickly get too cold to support tropical fishes. If the OP jury-rigs some kind of temp control that shuts off the flow, then the water in the freezer will...freeze up.
That's the biggest reason most of the home- made chillers use a fridge rather than a freezer.

 

[deadlyapp]

The problem with that is controlling the tank temp. If the "chiller" runs 24/7, then it will quickly get too cold to support tropical fishes. If the OP jury-rigs some kind of temp control that shuts off the flow, then the water in the freezer will...freeze up.
That's the biggest reason most of the home- made chillers use a fridge rather than a freezer.

Yeah - he'd need to set up the controller to turn off the fridge, rather than turn off the flow in the chiller, or both if he wants to conserve the most electricity.

 

[Charmonium]

..

 

[Paperdoc]

Concern about the fridge unit running constantly is a good point. No fridge is designed for that. In fact, if you were to check a normal fridge, I bet it runs no more than about 20% of the time. So, much heavier use WILL wear it out faster.

Yeah, my point about freezing up the water line relates mostly to when the water loop flow stops, which may NOT be part of OP's design. OR, the design and operation might include running it with NO temperature control system, but with a timer so it shuts off during the night. Even low flow MAY not be enpough to prevent freeze-up if the fridge or freezer is set to go below 32F (0 C). So a freezer capable of going much colder but NOT set to do so will not give more heat removal.

If the water cooling loop system is set to shut off somehow (either by timer, or based on fish pool temperature), that would provide enough control as long as the fridge's own thermostat is set to just above 32F. Then, whenever the source of heat (the water loop) to the fridge interior is cut off, the fridge will turn itself off.

 

[snoopy7548]

Why would you even want an outdoor aquarium anyways? Nevermind that it's in Texas. Keeping the water cool will cost a fortune.

 

[Arx Allemand]

First of all if you're serious about this just dismiss the idea of using a fridge or freezer. A large one has has just over a tenth of a ton of refrigeration capacity. The hermetic compressor is designed for a low duty cycle application so running 24/7 will greatly shorten the life of the compressor oil, windings and valves.

It's also very inefficient to run water through coils of hose inside the icebox. Water isn't going to freeze if its moving.

A proper chiller will use an evaporator whose wetted parts side is made of a metal that's neutral (ex. stainless steel, titanium). It will also have a proper thermostat or control to prevent over cooling and other faults that can occur during normal operation.

Your heat load in Houston is very high. How big is the aquarium?