HERMS Tubing 1/2 vs 3/8

[JayInJersey]

Question for you math guys out there...

how much more efficient would 1/2" tubing be over 3/8" tubing?


As I'm rebuilding my HTL I'm adding a SS HERMS coil inside it anca I can get a good deal on a 3/8" 50' SS immersion chiller...and since that is already "coiled" that would save me some time and effort.
But that chiller is about the same price as 50' 1/2" non-coiled from McMaster...

So I'm trying to do a cost analysis deciding if the effort and cash savings on the 3/8 is enough to warrant it over the 1/2.

Thoughts?

 

[P-J]

The temperature will equalize (inside/outside temp) in the 3/8" OD coil within about 16'. After that it is simply a waste. I'd go with the 1/2" OD tubing. The flow rate will be much higher and your overall performance will be 4 times greater.

IMHO

 

[JayInJersey]

16' eh? Maybe I don't need the whole 50' then...


But can I utilize the 4x greater flow rate during a HERMS recirc?

 

[strat_thru_marshall]

The temperature will equalize (inside/outside temp) in the 3/8" OD coil within about 16'. After that it is simply a waste. I'd go with the 1/2" OD tubing. The flow rate will be much higher and your overall performance will be 4 times greater.

IMHO

At what flow rate? If it equalizes after 16', then why would the larger diameter at the same length give better cooling? Whats the calculations used here, im not a scientist and i would love to know more details here.

 

[Red Clay]

I went ahead and went with the 1/2" Stainless (0.02" wall thickness) from McMaster. It wasn't too much more than the similar ID copper tubing. Since I'll only use 30 feet or so, I'll have tubing available to make pickup, whirlpool and other handy gadgets.

<thread-jack>
Speaking of that, what's the best type of tubing bender for thin-walled stainless 1/2 tubing for just occasional use? Do I need to pay $100+ for a bender, or will one of those $50 harbor freight hand benders get me by for a few dozen lifetime bends?
</thread-jack>

 

[P-J]

At what flow rate? If it equalizes after 16', then why would the larger diameter at the same length give better cooling? Whats the calculations used here, im not a scientist and i would love to know more details here.

Turbulant flow is the issue when using an immersion or counter flow heat exchanger. The fluid needs to flow fast enough inside and outside the tubing so that the barrier layer next to the tube is broken. This is the reason why stirring the wort during chilling with an immersion chiller yields much shorter cooling times. Larger ID tubing requires faster flow rates to be efficient.

(Excerpts from an article at The Brewery.org)

" ~~ turbulent flow is achieved in a 1/2 " tube at .11 m/sec, in a 3/8" tube at .14 m/sec, and in a 1/4 " tube at .22 m/sec, which quite simply means in each case:

*put 5 gallons through your (1/2":3/8":1/4") exchanger in under (22:31:46) minutes and you have turbulent flow*, (Charlie's Law)

The overall coefficient of transfer jumps from about 1.25 KW/m² K to about 12.5 KW/m² K ! Fast flow systems rule,~~~ "

HTH

 

[P-J]

<thread-jack>
Speaking of that, what's the best type of tubing bender for thin-walled stainless 1/2 tubing for just occasional use? Do I need to pay $100+ for a bender, or will one of those $50 harbor freight hand benders get me by for a few dozen lifetime bends?
</thread-jack>

Harbor Freight 1/2" x 7/8" tubing bender for $33 should work well for you.

 

[hot_carl]

I don't mean to dig up an old thread, but I'm having the same conundrum...I have 1/2" ID everywhere else in the brewery as high flow for moving and whirlpooling is a requirement. However, when recirculating mash through a HEX, how fast are you actually pumping? I have to throttle my pump back significantly to prevent the grain bed from compacting and gettign a stuck mash. Is 1/2" OD really necessary since the same volume of liquid would be moving FASTER through 3/8" tube and creating the turbulent flow? I would think that for the rates that are pumped at during mash recirc. that 1/2" tube may actually be less efficient...the added bonus is that 25-30' of 3/8" tube will be shorter (in height) for the same coil diameter and require less liquin in the MLT/HEX to operate.

 

[Lambo3]

I don't mean to dig up an old thread, but I'm having the same conundrum...I have 1/2" ID everywhere else in the brewery as high flow for moving and whirlpooling is a requirement. However, when recirculating mash through a HEX, how fast are you actually pumping? I have to throttle my pump back significantly to prevent the grain bed from compacting and gettign a stuck mash. Is 1/2" OD really necessary since the same volume of liquid would be moving FASTER through 3/8" tube and creating the turbulent flow? I would think that for the rates that are pumped at during mash recirc. that 1/2" tube may actually be less efficient...the added bonus is that 25-30' of 3/8" tube will be shorter (in height) for the same coil diameter and require less liquin in the MLT/HEX to operate.

I'm digging up an old thread, but I kind of agree with the above opinion and nobody replied. 3/8 copper is much less expensive than 1/2, and it seems like you have to limit the flow anyway, so, doesn't 3/8 get the job done then?

Thoughts anyone?

I was going to go with a 50' coil, but perhaps 25' is all I need. My system is built on keggles, so 10g batches are the max.

 

[P-J]

I'm digging up an old thread, but I kind of agree with the above opinion and nobody replied. 3/8 copper is much less expensive than 1/2, and it seems like you have to limit the flow anyway, so, doesn't 3/8 get the job done then?

Thoughts anyone?

I was going to go with a 50' coil, but perhaps 25' is all I need. My system is built on keggles, so 10g batches are the max.

A 50' coil is out of the question. 25' is more than an enough length to establish temperature equalization inside to outside. (Actually, equalization normally happens within 15 to 18' of flow.) The 3.8" OD copper is just fine for your mash recirculation.

Just something to keep in mind: When you have the copper coil in the HLT to maintain the mash flowing through it, the HLT water also must be recirculated on the outside of the coil to prevent a barrier layer . (Stir motor or pump recirculation.)

I hope this helps.

P-J

 

[UofMontanaAlum]

Just something to keep in mind: When you have the copper coil in the HLT to maintain the mash flowing through it, the HLT water also must be recirculated on the outside of the coil to prevent a barrier layer . (Stir motor or pump recirculation.)

I hope this helps.

P-J

I tried recirc'ing my HLT with 25' 3/8" copper HEX during mash for the first time last week and was blown away at how much this makes a difference. I had brewed 10-15 batches on my HERMS prior without HLT recirc and always had a hard time maintaining temps unless I cranked the HLT temp way up. Now I can keep my HLT relatively low and my mash temps hold rock solid. Mash out is faster too, what used to take 40 mins to go from 152 to 170 now only takes 5-10 mins.

 

[mjackson]

So I have 25' for 3/8" OD copper that I have left over from a CFC build. I am getting ready to build my hex. I am going to be utilizing keggles and hopefully brewing 10 gallon batches. Will the 3/8" OD tubing be an issue if I use 1/2 QD's throughout the res of the build. The only place I see volume being an issue would be on the exit of the hex before the wort reenters the MLT.

Thanks

 

[mjackson]

Bump

 

[Dog House Brew]

Started with 3/8" and then moved to 1/2" because the 3/8" restricted my flow too much. It made a big difference when I could set the grain bed and then virtually run the recirculation full go. I bought an immersion chiller and cut the ends off. it was 50' so it is overkill, but it works well.

 

[mjackson]

Did it work though that's my question? I have the 25 ft of 3/8 and I would like to use it at frost at last to keep the cost down. Need to keep swmbo happy. I understand the 1/2 is the preferred method but what's the downside of the restriction, just time?

 

[Lambo3]

Did it work though that's my question? I have the 25 ft of 3/8 and I would like to use it at frost at last to keep the cost down. Need to keep swmbo happy. I understand the 1/2 is the preferred method but what's the downside of the restriction, just time?

Simply answered, yes, 3/8 will work. You might take longer to get up to mash out temps, or do step mashing