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.
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?
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.
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.
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.
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?