DIY Counter Flow Chiller

[BillyZ]

I mentioned a counter flow chiller that my brother and I developed for use in brewing beer that is capable of taking boiling water down to room temperature in seconds. I was asked to post up some quick info about it so I felt I might as well share with everyone here in the DIY section. I had one realization as I was sketching this out. Our original design (the one we're using) uses copper tubing for the inner tube (see diagram) because of it's efficient heat conduction. This, many will argue, will not work well for a salt water aquarium. I believe you could substitute PVC fittings and a plastic inner tube (preferably thin walled) and still get good results. This is an extremely efficient system and may be overkill for many of you. But for anyone will large tanks or if you often run into extreme temperatures this may be useful.

WARNINGS:
DO NOT SUBJECT YOUR TANKS TO RAPID TEMERATURE CHANGES! A RAPID TEMPERATURE CHANGE CAN KILL YOUR TANK INHABITANTS FROM SHOCK.


Principle:
The unit consists of two main pieces of tubing. The larger tubing constitutes the outer housing for the inner tubing and also the flow housing of the coolant/waste water. The smaller tubing is the flow tubing of the tank water. The direction of flow in the inner tube is opposite the direction of flow of the outer tubing. As the water in the inner tube flows through the coil, the water in the outer tube chills it. The speed at which new cold/waste water flows through the outer tube can be adjusted to control the amount the tank water is chilled.

Parts:
1 garden hose
1 aquarium pump
X feet of plastic tubing. This tubing will need to fit inside the garden hose and also be attached to the pump. The length of the tubing will depend on the degree of temperature change you want. The length of this plastic tubing will be used for both the coil, the feed and return tubes for the tank.
2 PVC "T" fittings. The straight flow of the "T" fitting will need to have an outer diameter to fit snugly inside the garden hose (see diagram) The "T" off of the fitting will be "stepped down" as close as possible to the outside diameter of your inner tubing (see diagram)
2 PVC step downs (if necessary)
1 tube of your favorite brand aquarium safe silicon sealant
1 spray nozzle (optional)

Instructions:
The garden hose will be cut into 3 sections. The first section will connect the coil to a house cold water faucet. The middle section will be the main coil. it's length will depend on how long of an inner tube you purchased. The third section will take the waste water to a house drain/sink. Determine the lengths you'll need for each of these sections by determining where the coil will be placed and how far it is to the nearest faucet/drain. Since you're cutting the garden hose anyway, you could use two garden hoses to give you enough length to reach the faucet or drain.

Once you have your garden hose trimmed to length run your smaller inner tube through the length of the middle section of the garden hose. This will become the coil. At each end of the coil run the inner tube through the PVC T fitting as shown in the diagram. If you're using a step down connector for the PVC fitting attach it as shown. Once you're sure all of your pieces are fitting together pull them apart just slightly apply the silicone sealant to all the joints then press them back together and smooth out the silicone.

Let the silicone set as per the instructions for that silicone.

You're now ready to connect things up! Connect the feed line of the garden hose to the faucet and place the waste end in the drain/sink.

Now connect the tank line from the WASTE end of the coil to the aquarium pump. This is not backwards. You want the tank water to go IN where the waste water is coming OUT. This is why it's called a counter flow chiller and this is what makes it so efficient. If you hook these up backwards it will still work but you will not have the same efficiency.

Connect the tank line from the house feed end of the coil to the return on your tank.

Turn on the faucet and check for leaks around each fitting!

Turn on the aquarium pump. The inner tube should be all one piece so there should be no leaks from this.

Wait by the tank for the water to come out the return end of the tube. It should be considerably colder than your tank.

Adjustment:
This system can be adjusted by changing the speed by which the water flows through the coil.
Adjusting the tap water:
-- Increasing the speed will make the water colder.
-- Decreasing the speed will make the water warmer.
Adjusting the Aquarium Pump:
-- Increasing the speed will make the water warmer.
-- Decreasing the speed will make the water colder.

[Anemoneman]

Look's like it would work but it is environmentally unfriendly to use here in the west where water is a premium item. Just got through a several year drought.

[d9hp]

Looks good, nice posting.

[BillyZ]

yes, that is a very good point Anemoneman. There is another option that I'm hoping TroutMan will post soon with some pics of one he built with success. No water waste with that one.

Thanks d9hp!