Size and length of immersion chiller and HERMS coil

Is there a major benefit to going 1/2" stainless tubing for a chiller and HERMS coil over 3/8"? Everything else is 1/2" all the way through so 3/8" would be a bottleneck. Probably going to do 100' for the chiller, but not sure how much I'll want for the HERMS. I'm thinking it's doubtful I'll need to be pumping so fast that it will matter.

I'm using copper, but my herms coil is 50 ft.

I don't know about the HERMS coil because I don't have a HERMS, but for the chiller, the higher your flow, the faster it will chill, so 1/2 is better than 3/8. Even if you only go with 3/8, 50 feet will be long enough - in fact, you would probably be better with two 25 foot sections in parallel than with a single 50 foot section - you will have less resistance and thus a higher flow rate. If you have a 100 foot, 3/8 chiller, the resistance in the line will really cut down your flow - if you have to have 100 feet, make it two 50 foot sections in parallel.

Just as important as flow rate for quick chilling is to keep the wort moving past the coils - either by manual or mechanical stirring, or by using a pump to recirculate wort and inject it at the top of the kettle to keep a whirlpool going.

I have a 50' 3/8" right now for 5 gal batches and I can crank the hose way higher than ever necessary. I'm probably going to do something like this. https://www.homebrewtalk.com/f51/diy-interwoven-rib-cage-immersion-chiller-106415/ All credit to RedIrocZ-28.
The plan is to knock it down to 100° with the hose and then recirc ice water with my sump pump. I'll test the flow through the 50' chiller with the pump.

DeafSmith said:

I don't know about the HERMS coil because I don't have a HERMS, but for the chiller, the higher your flow, the faster it will chill, so 1/2 is better than 3/8. Even if you only go with 3/8, 50 feet will be long enough - in fact, you would probably be better with two 25 foot sections in parallel than with a single 50 foot section - you will have less resistance and thus a higher flow rate. If you have a 100 foot, 3/8 chiller, the resistance in the line will really cut down your flow - if you have to have 100 feet, make it two 50 foot sections in parallel.

Just as important as flow rate for quick chilling is to keep the wort moving past the coils - either by manual or mechanical stirring, or by using a pump to recirculate wort and inject it at the top of the kettle to keep a whirlpool going.

Click to expand...

Good point. I have a 70' combination HERMS/Immersion coil that ran too slow. I split it in to two-parallel coils and it rocks. I think that a 1/2" would be nice. Be careful to not have it too long. When the coil is really long, they often have all of the coils stacked upon each other and create a kind of "cylinder which no wort to water can pass through. having the liquid pass freely past the coils adds to the effectiveness.
Below is a photo of my HERMS/Immersion coil with a stirring paddle.

Go with 1/2" and bypass possible disappointment. I went with a 3/8" HERMS coil and the flow reduction is a deal killer. I'm now shopping for 1/2".

lol I've got the opportunity to build my dream brewery here and disappointment is to be avoided for reasonable cost. I'll definitely price 1/2" out.

mpcluever said:

I have a 50' 3/8" right now for 5 gal batches and I can crank the hose way higher than ever necessary. I'm probably going to do something like this. https://www.homebrewtalk.com/f51/diy-interwoven-rib-cage-immersion-chiller-106415/ All credit to RedIrocZ-28.
The plan is to knock it down to 100° with the hose and then recirc ice water with my sump pump. I'll test the flow through the 50' chiller with the pump.

Click to expand...

Recirculating ice water is where you will run into flow restriction problems. Water from the tap is under enough pressure to get very good flow through 50 feet of 3/8 tubing, which is what I have (copper), but most pond or sump pumps don't develop anywhere near that much pressure. I recirculate ice water (after cooling to 90-100º) with a 1/6 hp pump rated for 1350 gallons per hour and 23 foot lift. When pumping through my 50 foot, 3/8 inch chiller and two 6 foot lengths of washing machine hose, I actually get about 65-70 gallons per hour (just over 1 gallon per minute). Even with this slow flow rate, it works well, but if I had it to do over, I would have used two parallel 25 foot sections instead of the single 50 footer.

I think my pump is 1/4 hp. I'll start considering 2 coils and 1/2" is sounding better all the time. I thought there would be a bigger price difference, but looks like ~$20 difference on 100'

mpcluever said:

I think my pump is 1/4 hp. I'll start considering 2 coils and 1/2" is sounding better all the time. I thought there would be a bigger price difference, but looks like ~$20 difference on 100'

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You will probably have a difficult time making 100' of 1/2" tubing fit without splitting it into two coils.

I am designing a HERMs system right now as well. It seems to me that the smaller the diameter of the tubing the more surface area of the wort is subjected to the heat of the MLT water, thus heating it more quickly.
My question is whether the goal really is to heat the wort that quickly. Doesn't a higher swing in temps make controlling the mash temp more difficult? Is it better to pass the wort through the heat exchanger more times and accomplish a slower, more consistent temp change?

I guess that's a good question. I was thinking I'd like to be able to bump up as quick as possible and stop.
As far as smaller tubing being more efficient, I won't doubt it, however, it's all about surface area and I calculate (probably wrong) that 75' of 1/2" tubing has the same surface area as 100' of 3/8". I'm thinking I'll probably get 100' of 1/2" and lop off 25-30' for the HERMS coil.

You are right... There is more surface area in the larger tube. I was thinking that a higher proportion of the liquid toches the surface, but that might be wrong too. Either way, I am going with 1/2 inch in order to maintain a higher potential flow rate. I also think I am going to run the sparge water through the tube, hopefully cleaning (or pre-cleaning) it after running wort through it in the mash process.

Hello Dear Homebrewer.
Im newbie here and hope doing right sending this message. Is your HERMS HLT coil 1/2"? What is the volume of wort are you dealing with? We are monting a 60 gallons HERMS system and I´m wondering about diameter and length for size batch size. Thanks in advance.

I have a HERMS setup and have a 50' 1/2" SS coil. I wouldn't even consider going smaller. Remember you're pushing wort (not water) through the coil with a pump which has less pressure than a faucet. The small particles that get pumped around the system affects the flow. Go big!

mpcluever said:

Is there a major benefit to going 1/2" stainless tubing for a chiller and HERMS coil over 3/8"? Everything else is 1/2" all the way through so 3/8" would be a bottleneck. Probably going to do 100' for the chiller, but not sure how much I'll want for the HERMS. I'm thinking it's doubtful I'll need to be pumping so fast that it will matter.

Click to expand...

Your correct in assuming a bottle neck will occur at the 3/8" spots. When I was building my first herms I used a 3/8" coil with 1/2" to 3/8" compression fittings. I was using a blichmann false bottom on a 40% wheat beer. I added some rice hulls and some of them passed through the false bottom and clogged the 3/8 compression connection. At first I thought I had a stuck sparge. When I was breaking the system down for cleaning I noticed the rice hulls had clogged the system.

So I think it's very important to make sure your not putting in any choke points along the path of the wort.

When I ended up building the final version I went 1/2" all the way through and paid a bit more for the high flow 1/2" compression fittings from stainless brewing, a few bucks more and I've not had any issues.

I don't use rice hulls anymore in the mash and I've even gone to a fine grind on my mill. I get a nice flow rate and very even/steady temp ramping.