copper and flash boiler build question

I have two copper wort chillers I don't use anymore since purchasing a plate chiller. I want to coil both of the copper coils together to give me 40+ feet of 3/8" copper coil. My plan is to run a 1/2 copper tube in the shape of an L from the bottom of my corny keg (which I have modified for the housing) up close to the top and then spiral the 40ft down around the 1/2 tube and have the water exit through the bottom. Is there anyway I can sweat the 3/8" coil together with a coupling of sorts and also to the 1/2 tube? Using compression fitting in an application with this amount of heat doesn't seem like a good idea, especially if one come loose and I need to tighten it. I was planning on using silver solder fyi.

Here a couple suggestions for the boiler build, cut the chillers into 10' lengths and see if the tubing will coil around a 3" or 4 inch piece of plastic pipe to make the same type coils that GreenMonti has. get a 1/2" X 3/4" copper pipe adapter to fit the 4 tubes in like they do on automotive headers and silver braze the tubes in, or braze them in sides or bottom of a 1"cap drilled for 3/8" tube and use adapter to get back to 1/2". Try and spread the coils so the entire area of the corny keg is covered so the hot gasses have to go through the coils not around the sides. Last suggestion is flow water in the bottom and out the top, efficiency is less but dissolved air in the water will make for erratic operation in a down flow design as the air seperates as the water warms and it will block flow through tubes.

Do you want to run steam, or just heat water?

The 3/8 copper will go around a 4" pipe pretty well. Just go slow in the beginning so you make sure you don't kink it. After the first wrap is on, it will go like clock work. I wouldn't use solder on the connections. I am with Kladue on the silver braze. On my boiler I managed to liquify a soldered joint that was outside my boiler.

Here is a shot of mine where I merged the 4 1/4" tubes into a 1/2" fitting. You just need a bigger fitting. This is silver brazed and I am glad it is.

I just want to be able to run water for my mash and sparge. I stopped by the local welding place and got some dynaflow brazing sticks and I assume I'm going to have to use an acetylene torch as a MAPP gas probably won't cut it. Currently I have two 20' foot coils. When I unclamped my wort chillers and just stretched it out it fits perfect inside the converted corny keg. The second coil was coiled around a 2.5" pipe so I was thinking I will run that down the middle and connect both of these coils to a 3/4" copper elbow for water in and another elbow for water out.

Ranger9913 said:

I just want to be able to run water for my mash and sparge. I stopped by the local welding place and got some dynaflow brazing sticks and I assume I'm going to have to use an acetylene torch as a MAPP gas probably won't cut it. Currently I have two 20' foot coils. When I unclamped my wort chillers and just stretched it out it fits perfect inside the converted corny keg. The second coil was coiled around a 2.5" pipe so I was thinking I will run that down the middle and connect both of these coils to a 3/4" copper elbow for water in and another elbow for water out.

Click to expand...

Your gonna need to get it up to melting point and that is about 1000*. Mergeing that much copper will suck up a lot of heat. I suppose you could try and use MAAP gas. I have melted the silver braze with a propane torch on a standard 1/2" copper fitting.

I am interested in what some have to say about the scale that will form. I purged out my copper for all the braze joints I did. The inside of my copper tubes are bright and shinny. The outside is a different story.