external heat exchanger ideas (herms)

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Alemaker

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I'm trying to come back to homebrewing after a long layoff. I put together a crude HERMS system with a PID controlled external heat exchanger. The heat exchanger was ugly. I used an old fermentation bucket, a lot of copper tubing, a 240V element, and some JB Weld.

What I really dislike about it, other than it was only temporary, is the amount of water I had to use to cover the length of tubing I had to use to get temps up quickly. The performance was pretty good.

I'm thinking of ways to make this better. What I would like to do, is cram a small amount of 1/2" copper tubing into a small container and use the power of my 240V element to make up for the difference in size. Water at atmospheric pressure (and I really don't want to do this at any other pressure) only gets to 212º, so I was thinking of using something like propylene glycol in the heating vessel. It boils at 370º, so I'm thinking I could get workable temps in under 10 feet of copper tubing, and the whole apparatus would take up very little space.

Has anyone done anything like this, or have any input?

Thanks!
 
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Alemaker

Alemaker

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If you have temps that high, wont the wort going through it become scorched?
Well, I don't know. The plan is to have the thermocouple reading temps on the wort outflow, so I don't think I will have any scorching problems if the max wort temp is 175. I don't think it would be nearly as risky as a RIMS system as far as scorching goes, since it's still indirect heating. It's kind of a HERMS and RIMS hybrid, I guess.
 
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Alemaker

Alemaker

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I am nost sure if this is what you are thinking of doing but check out this post. https://www.homebrewtalk.com/showpost.php?p=795051&postcount=49 that is what I made. It uses a 2 gallon cooler and a 1200w 120v heating element. I use this for my HERMS system and it works very well. I used about 18-20 feet of 1/2 copper in mine.

Mike
Yeah, that's what I'm talking about, but I'm thinking even smaller. Like even half that size.

Ideally, I'm thinking it would be in a length of wide metal pipe due to the high temps I'm thinking of. Like a fat RIMS pipe, if that helps.
 
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Alemaker

Alemaker

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http://www.philrobins.org.uk/

This guy's heat exchanger is exactly what I want to do. He's using around one foot of 6" copper pipe for the container (converted from his metric) and 10mm copper tubing which is somewhere around 3/8".

I want to keep at 1/2" tubing for flow, but I am not very skilled at coiling copper tubing, especially 1/2". Anyone have some tips on creating a super tight coil with 1/2" tubing?

Also, where's a good place to find 6-8" wide pipe?
 

Bobby_M

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If you're going to run the heat source really hot, you shouldn't need all that much wort surface area How about just doing a 2-pass with 1/2" copper inside a 2" shell?
 
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Alemaker

Alemaker

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If you're going to run the heat source really hot, you shouldn't need all that much wort surface area How about just doing a 2-pass with 1/2" copper inside a 2" shell?

That's not a bad idea. I guess I could do something like that. I think 2" may be a bit tight with the element in there. Maybe 3" would do it. I guess instead of bending the tubing, you'd solder fittings to make the angles?

The length of tubing needed for my desired flow rate and temp performance is the big unknown. My goal is efficiency and speed since I will be heating my strike water for 10 gallon batches with this. My element is 5500 watts, so I think I have more than enough power.
 

GuateBrewer

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Might be a dumb question/comment but will the PID run the pump or the element? Seems if you are running the PID to the pump and the pump is at times shut off, then you would have the wort in the heat exchanger burning in the 300 degree water??
 
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Alemaker

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Might be a dumb question/comment but will the PID run the pump or the element? Seems if you are running the PID to the pump and the pump is at times shut off, then you would have the wort in the heat exchanger burning in the 300 degree water??
PID runs the element.
 
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Alemaker

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I wonder...I could potentially eliminate my HLT with this. I may be able to hook up a water hose to the system. Just turn a couple of valves, and the pump is no longer sending wort to the heat exchanger, it's going into the boil kettle. Turn a couple more valves, and water from the house is going through the heat exchanger and fly sparging. This could work since sparging would be done with a low flow and may have enough time to heat up. I'm in Texas so my ground water is always pretty warm.
 

Bobby_M

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You could also think about not doing a liquid to liquid heat exchange at all. Why not use a low density element in a narrow tube and run the sparge water/wort through in direct contact with the element? I keep messing around with this idea in my head well in advance of getting an electrical service upgrade. You could modify the inlet to receive either cold tap water or wort from the MLT drain in a recirc situation. I think having a way of pulling the element's output back for this step would be nice... like running it at 120v.

 
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