Whirlpool IC / new AG system design advice

[emcdermid]

I'm looking to build a whirlpool IC as part of a new all-grain system and could use some design advice.

First, the background - after years of extract-only brewing on a primitive setup, I'm taking advantage of having workshop space I can now dedicate to brewing, and am building up a 3-vessel, 2-pump, single tier AG system. I'll be using propane to heat initially, but am planning to shift to a fully electric HERMS system once I can assemble all of those components.

My boil kettle is a 16 gallon Bayou Classic 1316 (15.5" diameter, 19.5" high), and I plan to do both 5 & 10 gallon batches. I've decided I want to go with a whirlpool immersion chiller for cooling, rather than a counterflow or plate chiller (I really like the idea of dropping the entire volume below 140 quickly, and leaving the break in the kettle).

Materials wise, I have 2 60' coils of 1/2" ID copper tubing available, plus a 10' length of straight 1/2" tube. I realize 120' of coil is probably serious overkill, but I picked it cheap, and figured it gave me both more options and a backup coil in case I really screw up the first time.

My main questions, though I'm sure there are more issues I haven't thought of:

1. Does it matter if the coil height is significantly less than the wort depth, or should that not be an issue as long as I'm using a pump and recirculation arm to whirlpool?

Just as a back-of-the-napkin calculation, 5 gallons should come in at roughly 6", and 10 gallons at 12" (not including the displacement of the IC itself, which would add another 1.2" if I use 60'). Assuming I'll lose that extra 1.2" and maybe a bit more when I go electric, it seems like the ideal coil height for 5 gallons would be no more than 6". That would mean it would only cover half the height of a 10 gallon boil, though, hence the question.

2. Assuming it does make sense to keep the height of the coil short, it seems like it would also make sense to go ahead and use an inner and outer coil (either in series or in parallel) since I've got the materials available. Does that make sense? I'm not sure if it really makes sense to go with a parallel feed, though - obviously it would chill quicker if I can feed it enough water, but I'm not sure if I can get enough flow for that from a 5/8" garden hose.

3. I gather one of the issues with an IC is navigating obstacles in the boil kettle, such as a temperature probe coming in from the side. I was thinking of using one of the large 8 5/8" diameter stainless hop spiders from stainlessbrewing.com in the kettle anyway, and it occurred to me that I could clamp an extra-long thermowell (maybe 16") to the side of the spider and drop a probe down into the wort from above that way. That *seems* like a really slick solution, but since I haven't tried it yet and haven't seen anyone propose it elsewhere, I'm wondering if there's some obvious flaw in that idea I'm missing?

Oh, and just a quick note about me: I am the kind of guy who likes to learn new skills, builds things for the sake of the experience of doing it, and is more than willing to try solutions that are a little out of the box (and sometimes way out). I'm reasonably handy, and though I've never soldered pipe before, I figure I can learn and am looking forward to it. I also have access to some metalworking equipment (lathe, mill, etcetera) and someone willing to teach me to use it, in case I need to (or more accurately, find an excuse to) fabricate something special like a mount for that thermowell.

Anyone willing to share suggestions/observations?

-- Eric

 

[mjohnson]

It seems to me that the two biggest factors are surface area and coolant temps. So the more copper you get in the wort, the faster it will chill. I'd bet, that since you are whirlpooling, it would not make much of a practical difference where in the wort the surface area is.

Keep in mind that as the coolant warms up as it travels through the chiller. So there might be diminishing returns on a long chiller if the coolant isn't moving fast enough.

Since you have so much copper, what if you made 2 chillers? One that hits the 5 gallon level and one that hits the 10 gallon level. You could make them so that one would fit inside the other. split the hose water going in so each got its own cold water feed. If it turns out you don't need both, I bet you could easily sell one of them (since you got a good deal on the materials - copper is expensive!).

 

[emcdermid]

That's a thought -two chillers might work. A variant of that might be to create two identical chillers, each sized for 5 gallons using a double coil. For a 5-gallon boil, I could use one as an IC and one for a pre-chiller, and for a 10-gallon I could put both in the kettle, one atop the other.

The latter approach only really works well if I can get enough water flowing fast enough through both, though - even if each IC has the inner and outer coil in series, the net result would be two 1/2" ID chillers running in parallel.

I suppose if I can't get enough flow, and the prechiller doesn't seem all that helpful, I can always sell off the spare (I got the coils when Home Depot was selling them off for ~34ish each).

 

[mjohnson]

I don't think I'd run them serially. I'd try to get each its own feed of cold water. In the end, how fast do you really need to chill? I bet there are diminishing returns in terms of amount of crap you have to put in your kettle. Why make things more complicated than they need to be.

I bet a chiller with one of those coils along with a whirlpool will be plenty fast for both 5 and 10 gallons. You could make two, sell one or give one to a friend, and buy a little pond pump for pumping ice water.

 

[emcdermid]

I didn't mean run the two chillers in series; I'd split the hose between them as you suggested. I just meant that rather than build two chillers of different diameters that nest, it might make sense to build two that stacked.

Unless I'm miscalculating, I couldn't use 60' to make a single IC shorter than about 9.5 inches high anyway, even if I left no space between the coils. So that would seem to imply an inner and outer coil for the 5-gallon one anyway, the only question would be whether the second one followed the same model, or was a single taller coil that fit inside it.

I agree, though, that unless there's actually an issue with using a shorter IC in the 10-gallon boil, using two 60' chillers is probably far more than needed to do the job. Sounds like the most important thing is that initial drop below 140; after that an extra few minutes to pitching temp isn't going to bother me. So the right answer might be just to make the 5-gallon version and see how it performs, then decide what to do with the other coil (whether that be build a pre-chiller, sell it, or whatever).

Any thoughts on the thermowell idea?

 

[mjohnson]

If you put a thermowell in the side of the kettle, I'd just try to make one that doesn't go too far in and I'd make the chiller to accomodate it. I bet it won't be an issue. You don't want the coil up against the wall anyway.

If you go the thermometer on the spider route, rather than using a thermowell (not sure how expensive they are), you could use one of Thermoworks long stem digital thermometers. I think they are on $30 for the 24". Might be handy for a mash tun too.
http://thermoworks.com/products/low_cost/rt610b_12+24.html

 

[emcdermid]

Thanks for the link - those might indeed be a good solution, especially at that price. They'd require looking down on the top of the kettle to read, but that shouldn't be an issue.

Just for reference, the thermowells I was looking at run about $12 each here: https://www.brewershardware.com/Straight-Wall-Thermowells

 

[emcdermid]

Also, breadcrumbs for anyone who might be reading this thread down the road - there are some great examples of ICs built with this tubing here: https://www.homebrewtalk.com/f51/what-have-you-built-hd-copper-tubing-442814

(Not sure how I missed that when I was searching for information before starting the thread, but oh well...)