# Silicon Hose Versus Copper For Herms Heat Transfer



## Brad Sofield (13/5/10)

Hi everyone- I was having a thought/brainwave about plumbing through a herms vessel. Mainly because I was having trouble cramming enough cooper into an 11 litre pot and then trying to connect the ends through the inlet /outlets. 
Does anyone have any experience or opinions on using 1/2 inch silicon tubing wound into a coil instead of copper or stainless. It would be alot easier to coil and connect and could be easily removed for cleaing etc. I know it transfers some heat as it burns the site out of my hands when I connect my hoses now.
Look forward to any responses.​


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## Bandito (13/5/10)

The common concensus is "it is not a good conductor". But the reality is that heat conduction is a function of wall thickness. So if you can source especially thin silicon tube when compared to the wall thickness of copper this might effect the equation to make it possible.

I will be using teflon tube with a very thin wall to make use of this part of the equation for my upcoming herms.

Of to find my physics book >> Currently uploading some photos of the heat conduction section of 'Physics for scientists and Engineers' See them here: http://s82.photobucket.com/albums/j248/ali...eat-conduction/ (First page is 1.jpg, last is 9.jpg)

Havent read it in ages, but should shed some light on the fundamentals. 

I will post thermoconductivities tomorrow night. 
Care to do the maths on 1/64" wall thickness teflon and 1/32" silicon compared to a real world copper wall thickness Lethal?


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## unrealeous (13/5/10)

This is my thinking...

Copper has a thermal conductivity about 28 times better than stainless steel (401 vs 14W/m K) - I can't find what silicon would be but I'd presume it would be less than 1, then you have to take into account wall thickness of copper vrs silicon hose (silicon is thicker so that makes it even less efficient)... Assuming best case you'd need need than 400 meters of silicon hose for a meter of copper to get the same heat transfer, or 28 meters of stainless for a meter of copper.

You can compensate for these poorer heat conductivity by increasing the temp of the outside water that the hose/pipe is in. Normally you are recirculating wort around 64-68 degress, so having the Herms liquid 10 degrees hotter than your target shouldn't be a big deal. For silicon you'd need hotter still.... but the upper limit for the outside liquid is 100 degrees as it will start to boil off, so if you don't have enough length you might not be able to get enough heat transfer...

But in theory it might work. Give it a try and see how it goes. At worst you'll have a good story.


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## lukewarm (13/5/10)

I suppose you could give it a go, but there's a reason copper is where it's at.


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## LethalCorpse (13/5/10)

Silicon tube is almost, but not quite, as ridiculous an idea for heat transfer as teflon. They both have terrible thermal properties and are both obscenely expensive compared to copper, though teflon is more expensive and therefore takes the stupidity crown. Silicone rubber has a thermal conductivity of about 0.2 W/mK , teflon about 0.25 W.mK. Stainless steel goes to about 16W/mK and copper hits around 400W/mK. Yes, that means that copper is about 2000 times better at transferring heat than silicone rubber. Also, you'll never find silicone or teflon tubing that has thinner walls than copper and isn't going to burst the first time you put liquid in it.

EDIT: beaten, mostly


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## unrealeous (13/5/10)

LethalCorpse said:


> obscenely expensive compared to copper, though teflon is more expensive and therefore takes the stupidity crown.


That's a very good point. . Economically silicon makes no sense.

As an aside, I bought a length of stainless tube, a pipe bender, then spent an afternoon trying to bend it into a coil. To make a long story short, I made a dogs breakfast of it... Now I'm using a copper coil, although still sorting out how to connect/seal it to the pot... a flexible tube win the workability cake...


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## raven19 (14/5/10)

You could just use a very short length of silicon at each end of your HERMS copper coil to connect to the nipple (assumed) on the pot wall - making it easier to remove for cleaning?

But with a pump I would have thought you would seldom pull the HERMS apart - just flush with PBW like many others do at the end of the brew day.


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## alowen474 (14/5/10)

lukewarm said:


> I suppose you could give it a go, but there's a reason copper is where it's at.


Looking at the table, if you need to spend more than you would for copper, you should use silver. It appears to have excellent thermal properties.
I dont know where you can get silver tube. Maybe a jeweller could weld a heap of rings together. That would allow you to get the eact curve you need.
Once you get it built don't drop it though and I'd do some research on cleaning products too.

Would look good though.


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## QldKev (14/5/10)

Here's an idea.  

Why don't we use a plate chiller for a herms.
We could have 2 ways of doing this.

Just drop the plate chiller into the pot of hot water, basically the same as the traditional HERMS, and circ wort through it. The pot of water heating would be controlled same as normal HERMS setups.
or 
Using 2 pumps, one to circ hot water from the HLT to the plate chiller and another pump to circ wort. The pump from the HLT would be controlled for wort temps. 

Even another idea, a counter flow herms coil. But would require 2 pumps again.


QldKev


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## Sammus (14/5/10)

Can eveyone please go and edit their posts to say "silicone" instead of "silicon"...its annoying me  I'm disappointed that even you managed to mix them up LC


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## QldKev (14/5/10)

silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon


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## Sammus (14/5/10)

::cries::


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## Bandito (14/5/10)

QldKev said:


> Here's an idea.
> 
> Why don't we use a plate chiller for a herms.
> /snip/
> ...




I like!

Isnt silicon the aussie spelling? and silicone the yankie way?


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## QldKev (14/5/10)

Sammus said:


> ::cries::



Sorry :lol:


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## unrealeous (14/5/10)

You say tomatoes....

http://en.wikipedia.org/wiki/Silicon

[Edit] but you might have a point - http://en.wikipedia.org/wiki/Silicone_rubber

Why is engrish such a cruel language...


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## Fourstar (14/5/10)

unrealeous said:


> You say tomatoes....
> 
> http://en.wikipedia.org/wiki/Silicon



and i say silicone rubber.
http://en.wikipedia.org/wiki/Silicone_rubber

silicon is to silicone hose as iron ore is to steel.


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## katzke (14/5/10)

QldKev said:


> Here's an idea.
> 
> Why don't we use a plate chiller for a herms.
> We could have 2 ways of doing this.
> ...



You forgot the obvious or left it out so I got confused.

Use the plate chiller to heat and then use it too cool.

Not sure how to calculate if the second pump would be cost effective. If you are running 100C water through it to heat the wort it would not take much and it may be less expensive to just dump the hot water. A second pump would be convenient and may be the best idea. You could calculate the step and only heat the water to what you need to make your change to the wort. Also if you have a bunch of hot water left you could pre-heat the wort when transferring it to the boil kettle.

Times like this I am glad I BIAB.


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## Lilo (14/5/10)

QldKev said:


> silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon, silicon




Sillycun????????


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## Batz (14/5/10)

Sammus said:


> Can eveyone please go and edit their posts to say "silicone" instead of "silicon"...its annoying me :


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## Bandito (15/5/10)

Sill havent had a chance to work out the proper physics equation to compare copper to silicon (and teflon for my benefit). But I see that it involves all of the following factors: 
1/ specific heat capacity of the tube material 
2/ wall thickness of the tube 
3/ surface area (probably both the outer and inner)
4/ rate of flow through the inside of the tube and over the outside of the tube
5/ length of the tube

Anyone have an equation that has all or some of the factors in it? It would be good to have a equation based on physics.


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## Lemon (15/5/10)

Bandito,
Copper has very good heat transfer, only exceeded by aluminium, very difficult to come by in standard tube sizes etc.
Silicon, and many polymers are in comparison quite good insulators.

Thermodynamics is the field that will answer your question definitively, but not many hot water heaters are made of silicon.

Hope it helps

Lemon


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## Bandito (15/5/10)

Lemon said:


> Bandito,
> Copper has very good heat transfer, only exceeded by aluminium, very difficult to come by in standard tube sizes etc.
> Silicon, and many polymers are in comparison quite good insulators.
> 
> ...




Thanks for the reply, I didnt want this thread to go dead, but actually, gold has the best heat transfer - density seems to be the driving factor.

I have wanted to start a thread on this topic for quite some time, and although I dont want to hijack, I would like to end up with a definitive answer in the form of an excel spreadsheet that could be used to determine the length of copper or stainless or silicon or whatever tube required to achieve an effective heat transfer.

The photos I linked to in post #2 were photos of a few pages from the thermodynamics section of my 1442 page physics bible. 

Google is showing a wealth of hits - there is hope yet!

http://www.google.com.au/#hl=en&source...07bcdde4ac46065


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## LethalCorpse (15/5/10)

Bandito, the question has been answered three or four times now. We're all acutely aware of your affinity for obscenely complicated or expensive solutions to quite straightforward problems, and your complete inability to listen to anyone who actually knows what they're talking about. Plese keep your quixotry in your own thread and stop clogging Brad's.


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## Bandito (15/5/10)

Comon lethal! I know you have the brains to formulate a proper equation to give an actual formula! An answer like 
"its a good insulator" just doesnt cut it at this level of thermodynamics - we need comparable figures taking the wall thinkness and flow rate etc into account. Help us out? Please!


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## Bandito (16/5/10)

LethalCorpse said:


> Plese keep your quixotry in your own thread and stop clogging Brad's.



Exactly! Zackeys is when you ass hole and your body smells exactly like dog shit:  

Jakob, keep things directed at me in my thread! You will see an apoligy from me there


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## benchick (16/5/10)

katzke said:


> You forgot the obvious or left it out so I got confused.
> 
> Use the plate chiller to heat and then use it too cool.
> 
> ...


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## pb unleaded (16/5/10)

I use a chiller for my herms system. It's very efficient. The chiller also gets a good clean during the process.
The second pump is from an old dishwasher.


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