HEX Redesign

I thought I'd post a couple pics of my redesigned standalone HEX for my eHERMS system. The original was based on a small Rubbermaid cooler (I believe it was 2.5 gallons) and the new one uses a 2.25 gallon Bain Marie pot. The coil is 10' of 1/2" I.D. copper tubing (same size and length as the old one). The weldless fittings are the Blichmann-style described by Kal on his site, theelectricbrewery.com. I still need to order a 1/4" stainless fitting for my temperature probe (the lone brass piece in the pic), but other than that it's good to go. It does have a lid as well even though it isn't in the pics.

this is awesome! i saw the small cooler HEX and decided to try it, but i was thinking of using a small stock pot just like this. thanks for posting!

lpdb185 said:

this is awesome! i saw the small cooler HEX and decided to try it, but i was thinking of using a small stock pot just like this. thanks for posting!

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No prob and I'm glad you found it useful

Hey microbusbrewery, this couldn't have been posted at a better time. I am in the process of trying to build the exact thing. I had imagined using an old cornie keg but this looks like it might be easier to work with. I also was going to just "drop in" the coil similar to a small wort chiller but I love the way yours goes through the walls. Could you please post a parts list and or any lessons learned during fabrication. Did you have any problems coiling the copper? any leaks? Have you tested the efficiency yet (ramp times)? Do you worry about any stratification? Sorry to question you to excess but I would like to know everything about this that is possible to complete my own build.

Thanks

Duuhh! I finally clicked the link and voila. There the info is. I am still interested in the performance of this thing though. Do you have any pics of the element enclosure and top of the pot?

rodduley said:

Hey microbusbrewery, this couldn't have been posted at a better time. I am in the process of trying to build the exact thing. I had imagined using an old cornie keg but this looks like it might be easier to work with. I also was going to just "drop in" the coil similar to a small wort chiller but I love the way yours goes through the walls. Could you please post a parts list and or any lessons learned during fabrication. Did you have any problems coiling the copper? any leaks? Have you tested the efficiency yet (ramp times)? Do you worry about any stratification? Sorry to question you to excess but I would like to know everything about this that is possible to complete my own build.

Thanks

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The copper wasn't too hard to coil. Copper work hardens so you just want to take it slow to make sure you don't kink it. It comes coiled and I started off slightly tightening the coil by hand, then I formed it around the crock of a mini-crockpot, then I formed it around a roll of duct tape for the final diameter.

As for leaks, the pot never leaked in my testing but I had a couple very small ones in the fittings themselves. These were fixed by tightening the fittings a bit.

Re perfomance, I just finished it last night so I haven't had a chance to brew with it yet. It's about the same size as my old HEX, so I'd expect the same performance. Both the old and new version use a 110V 1500watt element. In the past I've been able to a raise the temp by a little more than one degree F per minute. For example, if I was mashing at 154F and raising to 168F for mashout, it would typically take around 11-14 minutes to raise the temp to 168F. That's based on measuring the temp of the wort exiting the HEX. I'm going to brew a Pale Ale next weekend so I'll post back if I notice any performance differences.

As for stratification, I'm sure there's some but considering it's such a small vessel and that I'm measuring the temp of the wort itself as it's exiting the HEX, I think it's negligible.

Sounds like you found the parts list on Kal's site. He does a great job of stepping you through everything so I'd definitely recommend checking it out. Speaking of his site, the element enclosure is basically the same as his; an outdoor double gang box with 3/4" fittings.

The lid is just a basic Bain Marie lid. I'm going to try to find a flat saucepan lid that will hopefully fit it better. Here's a side view that shows the electrical box and you can kind of see the lid. I did a little write-up on my blog too, http://www.microbusbrewery.org/2013/03/heat-exchanger-redesign.html

A small 12vdc motor on the lid would spin the water just fine. Moving the water will make it much more efficient.

I'm going to steel your design ... oh the flattery!

You can save quite a bit on fittings if you just solder the copper through flared holes in the pot (if you can assemble the flaring tool for cheap).

Monster Mash said:

A small 12vdc motor on the lid would spin the water just fine. Moving the water will make it much more efficient.

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The current lid doesn't fit tight enough to do that; it would probably rattle and drive me crazy. I was thinking about using a small DC pump to recirculate the water in the HEX but like I said the original one worked very well so I don't anticipate any issues with this one. Sure it would be more efficient if the water was moving but if it works fine without it then I'm going to keep it simple.

This design fits what I am trying to do at this point enough that I just started searching for a Bain Marie to build one of my own. I'm thinking about maybe using an aquarium pump and use the bubbles to mix any stratification that may occur. Please keep us posted on the results of your first brew using this.

rodduley said:

This design fits what I am trying to do at this point enough that I just started searching for a Bain Marie to build one of my own. I'm thinking about maybe using an aquarium pump and use the bubbles to mix any stratification that may occur. Please keep us posted on the results of your first brew using this.

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Definitely, I usually brew on Sunday so I'll post an update Sunday afternoon/evening. I like the aquarium pump idea.

Looks great! Can't wait to hear how it works for you.

So I brewed a pale ale using the new HEX yesterday. I also ended up building a new HLT and a new MT out of stainless steel stock pots. I missed my initial strike temp by about 8F. The HEX did a good job and I was able to bring the temp up to my desired mash temp in a few minutes. I timed it and I was able to raise the temp by almost 1.5F per minute. This is slightly better than with the old HEX as it was about 1.2-1.3F per minute. The volume of the new HEX is slightly less than the old (2.25 vs 2.5 gallons) and it also has a little more tubing in the coil than the old one, but the elements are the same (1500w).