Thoughts on a 2 stage counterflow chiller

[interplexr]

I am planning to build a counterflow chiller and had a couple thoughts that may or not make practical sense. In the winter my tap water is decently cold and to hot in the summer. I was thinking of making a 2 stage CFC to try and give me some flexibility with this. I've done some searching and haven't seen anything along the lines of a 2 stage CFC (I'm sure I just can't find it).

I don't have any equations to back this up but I was thinking of getting 25' of 3/8 tubing to make the CFC. I could then make 2 CFC coils with the first coil using tap water and the 2nd using ice water recirc. My thoughts would be to use the first 15 feet to get the temp down to near 100 degF or so and then use the remaining 10 feet to get the temp down to the desired temp with ice water recirc. In the winter I would just parallel the tap flow and not use the ice water.

Would this work or has anyone tried something like this?

 

[P-J]

It will work very well for you. However (IMHO) your copper length needs to be a little longer. 25' on the first stage and then at least 15' on the second stage. I've used this setup and it works very well. The rig I built is copper in copper CFC's using 1/2" OD inner tubing. Here is a pix of the 2 parts:

 

[interplexr]

I'll go with 25 ft for the first coil then and see where I need to go from there.

What about spriraling 14ga copper around the tube before putting the hose around it? I saw this on someone's youtube post on their CFC. I imagine this would make turbulent flow and increase the effectiveness of the cooling.

 

[P-J]

I would think that you would need to solder the wire in place and then you would still have a serious job inserting the tubing in the hose. Personally, I dont think it is necessary as you will have very strong turbulance in the hose as there should be strong flow using tap water.

I've built quite a few copper in copper CFCs and had real difficulty inserting the one into the other. I'd get it pushed about 3/4 of the way and it would jam up on me. I changed the method by pulled the inner tube in place.


I'd suggest that you get a 40' piece of fine aircraft cable and a 3/8" x 1/4" copper plumbing reducer, both from Lowe's. Solder a small (1/4") piece of 1/4" copper tube into the fitting and put one end of the cable through it and either solder the cable or tie it off on a small nut so that it is really secure and cannot pull back through.

Next, pass the cable through the hose (you might have to push a piece of stiff wire through first and pull the cable back) and tie it off to something very secure. Solder the reducer to the end of the 3/8" pipe and then pull the hose back over the 3/8" pipe.

(The pictures are of copper in copper - but should be the same process for copper in hose)

It works really slick and the pipe does not jam up inside the other. When done, unsolder or cut the reducer off. The 2 should be about the same length, one inside the other.

Anyway, I hope this helps.

 

[Bobby_M]

It's not that bad if you straighten the tubing and lube it with some dish detergent.

 

[ClaudiusB]

I was thinking of making a 2 stage CFC to try and give me some flexibility with this. I've done some searching and haven't seen anything along the lines of a 2 stage CFC (I'm sure I just can't find it).

Would this work or has anyone tried something like this?

It does work very well.
I no longer use ice water for the second stage since I built the glycol chiller.
The CFC's are purchased items.

Originally Posted by P-J
The rig I built is copper in copper CFC's using 1/2" OD inner tubing. Here is a pix of the 2 parts:

P-J you got the talent to do it.

My chiller and oxygenation cart

Cheers,
ClaudiusB

 

[interplexr]

What about using 3/8 ID tubing for the CFC? Is the 5/8 hose and 1/2 T with fittings to small? It all fits together but the clearance seems a bit tight. I have the 3/8 ID tubing so I thought I might be able to use it. Now that it's in the hose it seems larger than I thought....I should have planned that a little better before putting the hose on the tubing......

If nothing else I'll just use this for my HERMS coil.

 

[P-J]

What about using 3/8 ID tubing for the CFC? Is the 5/8 hose and 1/2 T with fittings to small? It all fits together but the clearance seems a bit tight. I have the 3/8 ID tubing so I thought I might be able to use it. Now that it's in the hose it seems larger than I thought....I should have planned that a little better before putting the hose on the tubing......

If nothing else I'll just use this for my HERMS coil.

Well - 3/8" ID is 1/2" OD. You would need at least 3/4" ID hose to accommodate it. With that you only end up with an 1/8" overall flow between the inner and outer circuit. That is really tight. With your setup you only have 1/16" overall clearance.

 

[Dgonza9]

I hesitate to admit it, but I used KY jelly to lube my copper pipe before inserting it into the hose. Man, even typing that sounds x rated. Worked great, though. And Bobby, thanks for your tutorial!

 

[klyph]

Well - 3/8" ID is 1/2" OD. You would need at least 3/4" ID hose to accommodate it. With that you only end up with an 1/8" overall flow between the inner and outer circuit. That is really tight. With your setup you only have 1/16" overall clearance.

Bendable copper tubing is spec'd to the OD, rigid copper is spec'd to the ID.

 

[P-J]

Bendable copper tubing is spec'd to the OD, rigid copper is spec'd to the ID.

Wait - Wait - Wrong.

The difference, bottom line, is the ID - OD measurements between plumbing and refrigeration copper. Plumbing copper is specified as the nominal ID of the pipe/tubing. Refrigeration copper is specified as the actual OD of the copper. You can go into Lowe's and buy a coil of 1/2" copper in a 50' length (Refrigeration copper [OD]) or get a coil of 1/2" copper in a 60' length (plumbing copper - nominal [ID]) that is actually 5/8" OD.

Most of the fittings and adapters are sized as plumbing copper. It's your job to figure it all out. Just saying....

 

[interplexr]

I'd say 1/16th is about right for the 1/2 rigid piping in the T. The hose has a decent amount of room but it looks like I'll pull it all back apart and use this tubing for a HERMS coil. I have a couple IC's that don't work with my new electric kettle so I'll just straighten one of them out and use it. With any luck, straightening them and rebending won't be to bad. I've had back luck with that on 1/2 soft copper tubing but it was also outside for a while. Lesson learned, check the clearance in the T next time and NOT just the hose.....

 

[klyph]

Wait - Wait - Wrong.

The difference, bottom line, is the ID - OD measurements between plumbing and refrigeration copper. Plumbing copper is specified as the nominal ID of the pipe/tubing. Refrigeration copper is specified as the actual OD of the copper. You can go into Lowe's and buy a coil of 1/2" copper in a 50' length (Refrigeration copper [OD]) or get a coil of 1/2" copper in a 60' length (plumbing copper - nominal [ID]) that is actually 5/8" OD.

Most of the fittings and adapters are sized as plumbing copper. It's your job to figure it all out. Just saying....

Hmmm, I've never seen coils of copper sized to the nominal ID. Live and learn.

 

[RegionalChaos]

When you say your tap water gets too hot, what temp is it at? I used my CFC for the first time the other day, and it only knocked temps down to 80 or so. Someone suggested slowing the flow of the wort in order to increase it's time in contact with the cooler water to try and chill more. I think I'm going to go that route next time. I had been toying with the idea of making a coil, like an immersion chiller, submerging that in a bucket of ice water, and using that as a second stage. I'm going to try slowing my flow first.

 

[interplexr]

I would say in the summer my water gets in the ballpark of 80. I don't have a ton of data though.

Lowes and Homedepot both sell soft copper tubing by the ID and some by the OD for what it's worth.

 

[mattmauriello]

i have a 25' cfc and an older immersion chiller im not using anymore. I'm planning on putting the immersion chiller in a bucket of ice water, then running tap water through the immersino chiller, cooling it even farther, then running through the CFC. I imagine that may make it even more effective than just the CFC, and I have wort running through less copper, so less to clean.yeah, i may have to stir the ice bucket now and then, but i think it shouold do the trick.

 

[jbreiding]

Why not split your water input hose before the cfc and connect both to a set of inline cfc's?

 

[mattmauriello]

Why not split your water input hose before the cfc and connect both to a set of inline cfc's?

he's saying that his ground water is coming out as warm as 80 degrees. no amount of CFC will get it lower than that, which is why he wants to introduce the ice water somehow

 

[Bobby_M]

Right, and heat exchange efficiency is tied directly to the difference between the two flowing liquids (the delta). When the boiling wort enters the tap water cooled chamber, the delta is like 130F assuming the tap is 80F. The wort should come out of that stage at about 85F with a decent flow rate. Now you have to introduce coolant with a larger temp delta than 5F. It doesn't take much ice to go from 85F to 65F.

This 2 stage CFC concept is an inline version of using tap water through an IC to knock down to 90F or so and then pumping icewater the rest of the way. The benefit is you get your fast single pass cooling back.