HERMS coil installation

[summerofgeorge]

Simple question but I haven't been able to find an answer. How far apart should HERMS coils be in a keggle? I would think you wouldn't want them to be touching. I'm just not sure how much space is optimal. If it matters, I'm installing 25' of 1/2 stainless and will be recirculating.

 

[jbguzzi]

Not sure what you mean by not touching. I think you mean coil to coil. I have a herms system with a SS immersion chiller and the coils are tightly wound and do touch. The coil is fully immersed and i recirculate the hlt water to help with the heat transfer. It works fine as is and the temp control is good, i can perform a mash out in like 15 min. I guess having the coils spaced out would help, but if you consider the surface area of the coil minus the area from the line contact of an adjacent coil its probably negligible. My opinion. Let it ride. It did take me 4-5 batches to dial in the system, there are more important players. If i just rambled on because i misinterpreted your question, sorry, had a long day! Good luck.

 

[jbguzzi]

 

[tally350z]

I am using the same size coil that you are getting, and mine are spaced out I believe its about 1/2-3/4". I can take a pic and post it tomorrow.

 

[summerofgeorge]

Not sure what you mean by not touching. I think you mean coil to coil. I have a herms system with a SS immersion chiller and the coils are tightly wound and do touch. The coil is fully immersed and i recirculate the hlt water to help with the heat transfer. It works fine as is and the temp control is good, i can perform a mash out in like 15 min. I guess having the coils spaced out would help, but if you consider the surface area of the coil minus the area from the line contact of an adjacent coil its probably negligible. My opinion. Let it ride. It did take me 4-5 batches to dial in the system, there are more important players. If i just rambled on because i misinterpreted your question, sorry, had a long day! Good luck.

Yeah, I didn't really know how to word it but you got it. I wasn't sure if it mattered if the coils were tight together or if there was a space between. I was thinking the extra space could only help with heat transfer.

 

[jbguzzi]

Ok, i certainly think it could not hurt. Since convective heat transfer is a function of area, delta t and the coefficient of heat transfer, the area player with coils touching or not would be a small or zero. Two cylinders in contact result in a line ideally, so the area gain in theory would be zero. So the next big player is the convective coefficient. Whirl pooling the water greatly improves that. Since you are essentially steady state dt is constant. That is why i think i don't have any issues. But all that hocus pokus being said, spacing a bit is better for maintenance and fabrication. Have fun and let us know how the system turns out!

 

[BadNewsBrewery]

As a fellow nerd, I enjoy the post above.

In simple terms - spacing the coils a little would help some, and would allow better flow around the HERMS, but if you're recirculating your HLT, there won't be an appreciable difference in what we do. If you ran the calculations and did a test in some ideal (unrealistic) engineering environment, you'd see a difference. In your basement or garage, you're not going to notice.

 

[jbguzzi]

One other issue i had with the immersion chiller i got. Stainless does indeed rust a bit if the layer of passivation is rubbed off. Where there was a line contact on the coils because being so tight together i had to scour the rust off, and re passivate. (passively! Haha, i don't have a bucket of nitric acid..) it was a pain. More reason to space them out a bit!