Herms copper

[aekdbbop]

When building a herms coil, which diameter of copper is best and why?also, what is the minimum length you would want to use? Thanks

 

[Prolix]

Personally my design has the temp probe at the wort return to the mash tun and a PID then controlling the the bath temp, using autotune. Then there are no real worries.


There are four variables to consider when designing a HERMS; flow rate, tube diameters, tube length and temperatures.

As the flow rate is not massive to avoid compressed grain bed and the temperature of the bath should be kept roughly constant at the required temp or just above, the heat transfer will not be great so the diameter and length or the tube are not that critical. 1m of 10mm copper would do fine, the smallest I would go for would be 0.75m of 8mm. (sorry for metric units)

Stainless is nearly 6 times worse at conducting heat so thats when you might need to worry a bit about diameters and lengths

The wider the tube the greater the heat transfer, up to a point.

 

[mplutodh1]

Check out this thread:

HERMS Heat Exchanger Survey

 

[aekdbbop]

I have 20' of 3/8" copper. Any reason why that wouldn't work?

 

[Prolix]

That would work fine