Using CFC and pre chiller not good enough.

[hukdizzle]

Well this weekend I brewed a 10 gal batch of APA and just bought a thermo that I can drop in the carboy to monitor the temp of the wort coming out of the chiller and I was surprised and pissed to see that it was at 80'F even after using a 20' 3/8" OD pre chiller in an ice bath and using a 30' CFC using the same size copper. The ambient temp was somewhere around 93'F and I actually kept all of the chilling equipment inside to make sure the copper didn't heat up past 70'F. I did a recirc back into the kettle and within about 7-8 minutes had the wort from 212'F to right at 140'F which I was very happy with, but past that it dropped very slowly with diminishing thermal exchange. After it hit about 125'F I went ahead and started pumping it into the carboy.

One thing that I do not have implemented on my system is a ball valve on the output side of my march pump that would allow me to slow the flow of wort and allow it more time within the CFC to cool down and one thing that I could not do at the time was check the temperature of the out side of the pre chiller but just by grabbing the output side line I could tell it was doing a pretty decent job of chilling the tap water down.

My question for you guys is this, what changes would you make to my system? I am thinking a ball valve is an essential part of the equation on the output side of the march pump to slow the wort flow but could I also look into getting some type of aquarium pump to actually pump ice cold water out of a bucket with instead of using the tap water? Do any of you guys use a setup that uses a source of ice water to pump through? If I just need to put a ball valve on and beef up the pre chiller to say maybe 50', I can do that pretty easily but I am wondering how much of a difference you guys think it would make.

 

[hukdizzle]

Here is a photo to kind of give you an idea of my setup although it's not currently running at the time, the recirc arm is sitting in the prechiller bucket instead of the kettle.

 

[Brewmasters Warehouse]

A ball valve will certainly help if you restrict the flow of the wort. How warm is your prechiller water getting? Even the best systems can only drop the temp to within a couple of degrees of the water temp.

I use a pond pump with a large container filled with ice and water and pump the water through the chiller in the summer time when the tap water is just too warm to get the wort to pitching temp. I recirc back into the BK until the batch temp is 140 or less, and then hookup the pond pump and ice water, with a return line back into the container with the ice water. That makes it pretty easy for me to get into the 60's during summer pumping from the BK to the carboy.

Ed

 

[hukdizzle]

Looks like I will be going with a pond pump because these florida summers are brutal to say the least. Thanks for the info Ed!

To answer your question about the prechiller bath water, it stayed right above freezing temp. I used 20lbs of ice in the pre chiller bath and during the entire process it never even came close to melting all of the ice.

 

[Catt22]

My best guess would be that the ice/water bath becomes stratified and loses it's effectiveness. The solution is to stir the ice/water somehow. A valve on the pump output is always a good idea and may help slow the flow and improve the cooling, but with the 1/4: ID tubing it should be fairly slow the way it is. You can stir the ice/water manually or use another pump to do it. I haven't tried it myself, but you could probably use an air stone and a large aquarium air pump to mix up the ice/water just like it would in an aquarium. Anything to keep the ice/water moving over the prechiller coils would help tremendously. Some of the guys use a small submersible pump like a sump pump for this. The first 70 deg drop is fairly easy to accomplish. The second drop to fermentation temps is more challenging.

 

[Monster Mash]

I use a post-chiller which works great. I run the wort from my boil pot through my CFC and then into a coil in an ice bath.

The wort comes out of the CFC at 75 degrees, goes into the post-chiller and comes out in the low 50's.

 

[Coastarine]

huk, I think you actually have a post chiller there too. Wort goes through the CFC, then through a coil in an ice bath, just like monster mash's? It is the same thing I tried when I did my lager and it didn't work for me at all. Two solutions: bigger coil for the post-chiller or slower flowrate. Also, you might not want to recirculate using this method. Consider just doing one slow pass straight from the kettle to the fermenter. When you are recirculating, any extra chill that you get from your post-chiller goes to cooling the hot wort in the kettle, which is work that the CFC could have done, and even if the chiller output was 60, once it went back through the CFC the tap water will act to warm it back up.

Another option would be to recirculate with the CFC without having the post chiller in the ice (basically get all of your wort down to tap temp), THEN put the post chiller in the icebath and do one slow transfer of the wort from the kettle, through the CFC (water doesn't even have to be on at this point), then through the icebath, then into the fermenter.

 

[hukdizzle]

It's a pre chiller, only tap water runs through it. My water flow goes from the tap to the pre chiller input, out the prechiller and into the CFC to counter flow against the wort and out into the grass.

 

[Coastarine]

Ahh, now I'm with you. Yeah, you can do better than that.

 

[Monster Mash]

You will do much better if you post chill the wort rather then prechilling the water.