Direct fire copper tubing...

Had a thought with another post. I havn't seen anyone yet that heats copper tubing with direct fire to get desired temps similar in idea to inline steam injection or a heat tube. I wouldn't think it'd be a good idea with wort but is it a good idea with water? Would it work similar to an infinate hot water heater? How much copper tubing would it take? What kind of burner would it take? I imagine that if a corny keg or similar diameter cylinder was cut up to make a cowling it would definately work better. I think a pressure relief valve somewhere would also be a must.

Would you want to copy the boiler on the old rig, but use copper tubing?. The old boiler is 4-10' lengths of 1/4" SS tube over a 6" 55 K burner. If you built one with 1/4" copper tube you could probably get by with 20-30 feet of tubing inside a 6" section of stove pipe, with one of the 4" metal fusion burners you could probably hit .5 gpm @140 deg rise. The more tubing you use the higher the flow rate you can run with 100+ degree rise. If you want to build one I would should you how to make the customized cross fittings for inlet and outlets, the rest of the construction is yours to learn on. Here is a few pictures of the old one http://picasaweb.google.com/kevin.ladue/InstantWaterHeater

I was just thinking to keep it simple I could coil up about 30ish feet of copper 1/4 copper and coil the hell out of it with a similar burner to what you have for that set up. ( maybe order a banjo burner, dunno still goofing with the idea )I'm pulling inspiration from both that design and THIS thread. Would it be good enough for only water for fear of scorchin the hell out of wort? I'm thinking more along the lines of rinsing grains and filling the mash tun with it. I don't like to rinse more than one quart per min. (otherwise in my experience my efficency sux!). Would a big copper coil suffice or would it actually be beneficial to drill and tap/silver solder the top plane of 2 swegelock 4 point fittings and get all complicated? I'm sure surface area would play a part in how important it would be but if a single coil of tubing was coiled to resemble a cone shape? Would that work better or worse than the 4 seperate coils? Also I havn't set a heighth restriction on this coiled monstrosity! it could be as small as 1 foot or as big as 5 feet! Dosnt' matter to me. It would be replacing my HLT so there would be space no matter how much it would take up!

I'm guessing that you'd want to coil it so that each coil varied in diameter unlike an IC. You don't want heat to be able to just fly past the coils. Another thing I was thinking was using heating baseboard since they have all those aluminum fins on the length of the pipe. Picture cutting 4 sections and standing them up in this stack. You'd use elbows to keep the flow running in series. I also have this cool coil that I salvaged out of an oil fired heating system. This was the source of hot water in the house. It looks like it ought to work, but I'm thinking about putting an electric element into a corny and installing this.

Bobby_M said:

I'm guessing that you'd want to coil it so that each coil varied in diameter unlike an IC. You don't want heat to be able to just fly past the coils...

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YES! Exactly. How tall should the stack be? Should I choke the top down with a reducer to retain more heat for the coils to collect or should it just be open? I was thinking another idea for the copper coil is to get a 3" pipe and wrap some 50' of copper tubing around it tightly to get a single tight coil. Then uncoil only parts of the coil to take up space inside the 6" pipe so that it would be more surface area more evenly distributed throughout the pipe. How does that idea sound?

I think it will be pretty difficult to acheive a shape that will be variable in diameter and also fit nicely in a stack. You might just go with a double coil. Wrap a tight coil around 3" pipe, then insert that inside a 4" pipe and continue wrapping in the other direction. I guess putting a 6" to 4" reducer on the top would help hold heat but you want to test to see if the burner runs clean like that. Reducing the exhaust will reduce the fresh air intake too.

Well, it's off to the scrap yard to look for some treasures. Maybe i'll find a buttload of copper cheap... Maybe I won't but I'll find something else fun. Never know with that place!

I LOVE the scrap yard!!!!! $24.00 for THIS COPPER TUBING!!!!!!!!!!





I'm thinking about using the burner off of THIS turkey fryer for the burner in the boil stack and upgrading the burner in that unit to a banjo burner for a more aggressive boil kettle burner. Checked out stove pipe at lowes and I'm thinking 6" might be ok if I can get creative about how I coil up my copper. The burner I'm thinking about using is 5.5 inches across so using a 4" stove pipe, sadly, is out. I'm goofing with the idea of coiling the copper down a 2.5" pvc pipe and unrolling a section here and there to take up space inside the stove pipe. A risky move becaue if I screw up my twenty four bucks are gone. After looking at the stove pipe my biggest hurdle is going to be figuring out how to keep the stove pipe together. I doubt that duct tape will work for the temps that will be blowing by. I'd like to get a SS double walled stove pipe section from the scrap yard but they are asking $35 bucks and just a galvanized section from lowes is just $5. For another $5 I can add an 8" pipe around the 6" pipe to make it double walled myself.

Would it matter which way the water flowed? If you put the cold water in from the top where the heat is undoubtedly the least then the water out at the bottom where the heat is the most wouldn't the water come out hotter? Kind of like a counter current wort chiller.

You could roll two 10' pieces of copper tube around a piece of 2" pvc pipe, spread coils 3/8" apart and mesh two coils together. After meshing coils measure length of coils and drill holes in side of stove pipe to match, and work tubing ends through sides of stove pipe and install fittings on outside for water in/out. Make bottom of coils at least 4" above top of burner to get complete combustion of the gas flame before it hits coils. Water inlet should be at the bottom inlet as the dissolved air in the water forms bubbles inside of the tubing and rescticts flow at low flow rates ( lesson learned on old system) in a down flow configuration.

That looks like 1/2" OD tubing and if it is, you're gonna have a hell of a time trying to pull a 3-4" coil.

Stainless stovepipe? Drool... you can polish the crap out of it but I understand wanting to save during proof of concept.

Bobby_M said:

....Stainless stovepipe? Drool... you can polish the crap out of it but I understand wanting to save during proof of concept.

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oh, it's beautiful... a bit dented, EVERY LAST ONE OF THEM at the scrap yard, but they are beautiful. Shinier than corny kegs. If this idea pans out It'll be back to the scrap yard picking out the least dented!

kladue said:

You could roll two 10' pieces of copper tube around a piece of 2" pvc pipe, spread coils 3/8" apart and mesh two coils together. After meshing coils measure length of coils and drill holes in side of stove pipe to match, and work tubing ends through sides of stove pipe and install fittings on outside for water in/out. Make bottom of coils at least 4" above top of burner to get complete combustion of the gas flame before it hits coils......

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good idea. So this idea is to T the bottom splitting it into 2 coils and T the top of the 2 coils into 1 out, right? I've got a question about the rigidity of the copper coils. Being soft copper am I going to need to reinforce the coils somehow to keep them from collapsing, bending, etc. or do you think they'll hold together alright because of the diameter of the coil size?

If it's 1/2" OD and you're going with a 5" coil or so, it's going to be pretty rigid.

From the picture you posted it looks like you have 3/8" OD copper tube. It would probably work out better if you wound equal lengths around a short piece of 4" plastic pipe and meshed the coils to fit inside of stove pipe. The copper tube will be rigid enough to stay put after coiling operation. The 6" cast ring burner should fit the bottom of the tube, but recommend about 1/4" gap between burner and tube for air to complete combustion of outer ring flames. Are you going to drill a hole in tube for ignition with a gas match or go all out and use a BBQ piezo igniter and rod. If you make next club meeting i will throw in a couple 1/4" Parker needle valves to play with for gas and water flow regulation.

Unfortunately I'm not going to make the next meeting because of work. Busy night at the casino. It is 3/8" tubing. Same as my counter current wort chiller and same as my immersion chiller. I am not sure if my math is right, in fact I'm sure it's WAY off but 10 feet of tubing wrapped around a 4 inch pipe would be almost 22 wraps. Think I'll call it 19 just to give myself some room at each end of the coil. 19 wraps of 3/8" would be 7.125 inches tightly wrapped without any room between each wrap. What are the chances that after seperating the coils I could keep it close to 15 inches? If the pipe is 36 inches long that's 26 inches left over. How many inches do I really need between the burner and the pipe? After how many inches of vertical wraps will the heat stop heating? I kinda figure if I have the extra tubing laying around might as well use it if it'll add even a few degrees. I havn't thougt about ignition yet. I figure I'll just use my trusty BBQ lighter. It's done me well so far... If I go all out and get a SS pipe from the scrap yard I'll be adding some kind of ignition for the flame!

Wrapping the tube around a 4" pipe will take up a bit more than 1 foot each turn so 10 feet would be about 7.5" tall when there is 3/8" space between coils. You should have at least 4" space above burner for complete combustion of flame. The longer the tube coils the greater the surface area and higher flow rate you can run and hit temperatures you want. As for length of pipe above coil it would help draft through coils but 6-12" above coils should be enough length.

kladue said:

Water inlet should be at the bottom inlet as the dissolved air in the water forms bubbles inside of the tubing and rescticts flow at low flow rates ( lesson learned on old system) in a down flow configuration.

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I'm wondering if copper is going to hold up well. DO in heater tubes can be very damaging.

Past experience with steam heated domestic water heating systems with copper tubes has been that the steel shell gives up before the water side copper tubes. Typical lifespan was 25+ years with chlorinated city water supply as a hard oxide layer forms on inside of tubing which provides some protection against further corrosion. Erosion of outside of tubing from combustion byproducts would be a bigger concern as this is what usually leads to the demise of the instant gas fired water heaters.

I've had some bad experience with copper tubed heat exchangers at the mill - too much pitting inside on the bends - looked like DO corrosion to us. For my money, they aren't worth 10 cents, but that is under constant use. For occasional home use, they may be fine.