A counterproductive counterflow chiller build

A blog entry detailing a successful counterflow chiller build over at Bertus Brewery today reminded me of my own failed attempt to build one. It is a bit of a sore subject, but I will discuss it now in hopes nobody repeats my mistakes!

This particular heat exchanger is sometimes referred to as a double pipe or a tube in tube design. It has appeared in Brew Your Own magazine, and a version is currently sold by JaDeD Brewing. It is a design that appeals to DIYers because it does not require any bending of copper. Additionally, since it only utilizes straight lengths of copper, it is easily cleaned and inspected.

I figured this counterflow heat exchanger design would be perfect for my counterflow-HERMS brewery due to the cleaning access. Besides for plate chillers (which I don’t think would work well in my brewery design) there were also not many counterflow wort chillers available in Canada at the time. To buy the sort of counterflow wort chiller I wanted I would have to order from the US, which I’m not keen on. So, in the Summer of 2014, I set out to make one myself.

To ensure my heat exchanger would have high efficiency, I decided to build it with 36′ of total heat exchanging length. I was going to be using sections of copper that were approximately the same length as my brewing bench – 6′. 3/8″ and 1/2″ copper tube was acquired at a local plumbing supply store.

 

Copper for CFC

 

After $2-300 spent, and an afternoon cutting and soldering copper in my garage, I had my chiller. This thing was a bit… bulkier than I imagined. No problem… it will be easy to clean, will mount under my brewing bench and will work wondrously… right?

 

CFC soldered up

 

Signs of trouble first appeared when I went to run some water through the chiller. The chiller provided so much resistance over its 36′ of total length that only a trickle came out. My vision of near instantaneous cool outs, and fast mash temperature control were beginning to crumble.

 

first run through CFC

 

I finished assembling it anyways, adding the remaining camlock fittings and silicone hose to connect the inner tubes of the heat exchanger. It turns out the flow restriction issues were two fold. Flow through the inner and outer areas of the heat exchange tube were both greatly limited.

 

IMG_8176

 

In my sadness, and eagerness to brew I pulled the trigger on a zchiller. With the shininess of my new chiller, and being able to finally brew my wounds started heal. All the while my failed heat exchanger found a home over the winter in the shed.

It occurred to me that this heat exchanger could be saved with just a little bit of work. Instead of a single 36′ heat exchanging length, I could set it up as 3 parallel 12′ sections. I wasn’t exactly in need of a heat exchanger anymore, but perhaps someone else could use it. None of this would matter though, as water was left in the chiller over that winter, destroying the inner heat exchanging tube.

 

IMG_8320

 

If you’re considering building a heat exchanger of this sort, I would suggest the following to you:

  • Keep the total length under 25′ (many copper CFCs have less than 15′ total length)
  • Use larger diameter copper if possible – 3/4″ and 1/2″ rather than 1/2″ and 3/8″
  • With the inner heat exchange tube especially, use type M copper which has the thinnest walls of any widely available rigid copper tube
  • Ensure that it is designed and mounted in a way allows the heat exchanger to be completely drained by gravity
  • Consider parallel configurations if higher throughput is needed
  • Consider just buying one! Copper fittings are expensive, and cutting and soldering copper is time consuming. Wouldn’t you rather be brewing?

Good luck!

  4 comments for “A counterproductive counterflow chiller build

  1. Brian
    May 20, 2016 at 6:51 pm

    When I rebuilt my brewery I went with the C-HERMS idea based on your setup. I love the idea of having a single external component that can be used for heating and chilling. I built my C-HERMS coil using 25′ of 3/8″ copper coiled inside 3/4″ PEX tubing. Total cost was $60 and it works great. Flow rate is just right, so I agree that more length is unnecessary and might cause too much resistance. I ruptured a silicone hose the other day running chilling water through it full-blast from my water line. That was my own fault, both using that much pressure and using a silicone hose for pressurized inlet like that. :)

    • Justin
      May 20, 2016 at 7:04 pm

      That’s awesome! Would love to see a picture of your brewery if you have any!

  2. John G
    January 8, 2018 at 10:55 pm

    Hey Justin. I know its been about two years since you did this build, but I’d like to see how you mounted the zchiller to the stand.

    • January 9, 2018 at 8:28 am

      Hey John. The folks st zchiller brazed a mounting bracket to my chiller at no cost. I then used some screws to attach it directly to the underside of my wooden bench top. Cheers.

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