HERMS Heat Exchanger

Im in the process of putting together my first all grain system, a HERMS system to make 10 gallon all grain batches. Stainless for the brewtus is ordered and being cut for me by a custom fabricator now. I hope to be welding it in the next few weeks. I am using three 15 gallon keggels for hlt, mlt and bk. Instead of placing the heat exchange coil inside the hlt I want to use a 5 gallon sankey keg that I have and use an electric heating element to heat the exchange water. The rest of the system will be natural gas. I want the 5 gallon exchanger because i will be able to more quickly adjust the exchange water in a smaller vessel, and to make clean up easier. My question is what size coil should I use so as not to create too much back pressure on the pump, I need to have a small enough diameter that it can be coiled inside a 5 gallon keg but large enough not to restrict the flow. Any ideas?

Hi

What pump are you planning to use? You can get low volume / high pressure pumps.

Also consider that with a 15 gallon MLT, you can only move wort just so fast. Unless you have a very unusual pump / coil combo, that's where your likely limit will be.

Bob

Bob,
Maybe I need to ask a lot more questions here. Perhaps in a 15 gallon system HERMS isn't the way to go. I haven't decided on which pump to use yet that probably should have been part of the question, so any suggestions would be great. Or if you think HERMS isn't the way to go, than any other suggestions on how to increase efficiency would be great. What ever system I end up with, I would like to be able to grow with without a complete redesign and eventually be able to brew 1 bbl batches. I have to go slow and steady here as swmbo hates the brewing hobby and thinks it a waste of money.

This is sort of like what I built except my HEX and HLT are electric and the boil kettle is natural gas. It's a five gallon setup, but I don't see why it wouldn't translate to a larger system. My standalone HEX is based on a 1500 watt 120v element mounted in a 2 gallon Rubbermaid cooler and 10 feet of 1/2" copper tubing. I use the March 809 pump on my setup and I have it throttled way back. You want to keep the flow pretty low so that you get good heat transfer and so that you don't compact the grain bed. I never have the ball valve open more than half way, so unless you're using really small tubing you shouldn't have to worry much about backpressure. Here's a link to my blog if you want to check it out. It's evolved a bit over the years so some of the pics are a little out of date but you'll get the general idea.
This link goes through the initial design: http://www.microbusbrewery.org/2009/03/herms-design.html
and this one shows more what it looks like now after finishing my brew stand:http://www.microbusbrewery.org/2011/10/finished-brew-stand.html

hepkat701 said:

Bob,
Maybe I need to ask a lot more questions here. Perhaps in a 15 gallon system HERMS isn't the way to go. I haven't decided on which pump to use yet that probably should have been part of the question, so any suggestions would be great. Or if you think HERMS isn't the way to go, than any other suggestions on how to increase efficiency would be great. What ever system I end up with, I would like to be able to grow with without a complete redesign and eventually be able to brew 1 bbl batches. I have to go slow and steady here as swmbo hates the brewing hobby and thinks it a waste of money.

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Hi

HERMS is fine, there are a lot of ways to do it. I think that electric is a bit challenging for most simply because it takes so much power to do well.

March and Little Giant both make pretty good pumps. March seems to be the more favored of the two. I happen to have had good luck with Little Giant. Just about any of them will likely work ok given a sub 1 gallon per minute flow rate. I'd go with how ever much tube is in a coil down at the big box store of your choice. I'd stay above 3/8" inner diameter just to make it less likely to plug.

Bob