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-   -   Separate HERMS HEX Build (http://www.homebrewtalk.com/f51/separate-herms-hex-build-160669/)

Bigscience 02-02-2010 01:54 AM

Separate HERMS HEX Build
 
After many years with a HLT heat exchanger, I want to build a separate, small volume heat exchanger. I have a 5 gal sanke I was thinking could be cut down to about half the size and then weld a coil in through the sides for ease of draining. For flow rate, I wanted to use 1/2" stainless tube, about 25' of it for good exchange. The diameter of the keg is 9.25" so I was thinking a 7" diameter coil would leave enough room for couplers/welding.

http://farm5.static.flickr.com/4040/...42d2b3e2_o.jpg

Here are the questions:

Can you bend 1/2" tube in a 7" diameter coil? I'm not assuming I can do this by hand but could a machine shop do it? I have a nice CFC that's in a 6.25" coil but that has 3/8 tube inside it so maybe that's why it didn't crush.

I emailed nybrewsupply and they said they could do it with 3/8" but didn't think it would work with 1/2". I really don't want to do 3/8" for flow reasons. Does anyone use a 3/8" coil and if so, how does it work out?

For the coupling through the keg wall, I was thinking about doing something like below BUT since it will be so tight, I was thinking about welding the elbows to the tube and then welding the elbow to the keg wall. Any other ideas on how to pull this off?

http://www.homebrewtalk.com/attachme...progress-5.jpg

Thanks in advance for the help.

The Pol 02-02-2010 02:09 AM

I have 1/2" SS coil in my rig, that stuff is TOUGH!...

Personally, I dont think you are going to be recirculating your mash fast enough for 3/8" tubing to make any difference, do you? 25' is plenty for the exchange, but I think your flow will be less than 1gal/min anyway which 3/8" can accomodate easily.

I personally wouldnt WELD the coil in. I used triclamps to mount mine in the kettle...

http://www.homebrewtalk.com/gallery/...m/P1030639.JPG

http://www.homebrewtalk.com/gallery/...m/P1030671.JPG

Bigscience 02-02-2010 02:38 AM

Since the diameter of the keg is only 9.25", there is really no room for triclamps or compression fittings to mess with. I'm not talking about a 1/2 barrel keg but a 5 gal sanke, cut in half to reduce the volume.

The Pol 02-02-2010 02:40 AM

Well, that is all I have to offer... that would be a tough weld job.

Dog House Brew 02-02-2010 02:51 AM

I don't think you could coil it that small w/o collapsing. I wanted to do the same thing. My Uncle owns a shop that rolls and bends metal. He said that trying to bend stainless tighter than a 10" coil would be nearly impossible. I was using the stainless coil material from McMaster. I forget the wall thickness, Just what he told me.

The Pol 02-02-2010 02:53 AM

Quote:

Originally Posted by Dog House Brew (Post 1854139)
I don't think you could coil it that small w/o collapsing. I wanted to do the same thing. My Uncle owns a shop that rolls and bends metal. He said that trying to bend stainless tighter than a 10" coil would be nearly impossible. I was using the stainless coil material from McMaster. I forget the wall thickness, Just what he told me.

FWIW, my 1/2" OD SS tubing is deformed from the coiling process. When I cut it and added the compression fittings, I had to re-round the ends, the coiling made the tubing oval in shape.... it is a 10" DIA BTW

Bigscience 02-02-2010 02:56 AM

Quote:

Originally Posted by The Pol (Post 1854112)
Well, that is all I have to offer... that would be a tough weld job.

The idea I was tossing around was to weld some 90s on the ends of the coil (it would look like yours is), drill 2 holes through the sides, pull the 90s through and then weld them on the outside. If it works out better, I could cut off the top and the bottom (minus some length) to do the welding and then weld them back on at the end.

If it wasn't already obvious, I really don't know much about metalworking and what's possible or not.

Bigscience 02-09-2010 04:14 AM

Element Coupler Straight vs NPT
 
I found a shop that will coil the ss tube for me and maybe do the welding as well. I need to buy the coupler for the element now. If I remember, heater elements are straight thread while NPT is tapered. What do other people use? I want to keep everything welded and not bulkheads.

Will this work?

http://www.buyfittingsonline.com/Fittings/item6494.htm

ThePig 02-09-2010 05:20 AM

Don't weld the SS coil to the bulkhead. You'll want to be able to remove the coil for deep cleaning, modification, etc... at a later date. I've taken mine out a few times and modified it to optimize length.

Take it to the welder and have him weld the tube to a matching tri clamp ferrule. Then have him roll that SS as tight as he can and use tri's (even 1/2" sabco tri's) to weld into the bulkhead. You should have enough room to make it fit if the welder can get the coil into a 6-7" roll.

diatonic 02-09-2010 06:26 AM

Quote:

Originally Posted by Bigscience (Post 1871130)
I found a shop that will coil the ss tube for me and maybe do the welding as well. I need to buy the coupler for the element now. If I remember, heater elements are straight thread while NPT is tapered. What do other people use? I want to keep everything welded and not bulkheads.

Will this work?

http://www.buyfittingsonline.com/Fittings/item6494.htm

Yep, that half coupling will work just fine. I bought one last week for my new HLT. I am considering replacing the black rubber seal that came with the element with a high-temp silicone o-ring though.

http://linus.webboise.com/imghost/pi...41d388762c.jpg


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